cryptlib.h

// cryptlib.h - written and placed in the public domain by Wei Dai

//! \file cryptlib.h
//! \brief Abstract base classes that provide a uniform interface to this library.

/*!	\mainpage Crypto++ Library 5.6.3 API Reference
<dl>
<dt>Abstract Base Classes<dd>
	cryptlib.h
<dt>Authenticated Encryption Modes<dd>
	CCM, EAX, \ref GCM "GCM (2K tables)", \ref GCM "GCM (64K tables)"
<dt>Block Ciphers<dd>
	\ref Rijndael "AES", Weak::ARC4, Blowfish, BTEA, Camellia, CAST128, CAST256, DES, \ref DES_EDE2 "2-key Triple-DES", \ref DES_EDE3 "3-key Triple-DES",
	\ref DES_XEX3 "DESX", GOST, IDEA, \ref LR "Luby-Rackoff", MARS, RC2, RC5, RC6, \ref SAFER_K "SAFER-K", \ref SAFER_SK "SAFER-SK", SEED, Serpent,
	\ref SHACAL2 "SHACAL-2", SHARK, SKIPJACK,
Square, TEA, \ref ThreeWay "3-Way", Twofish, XTEA
<dt>Stream Ciphers<dd>
	\ref Panama "Panama-LE", \ref Panama "Panama-BE", Salsa20, \ref SEAL "SEAL-LE", \ref SEAL "SEAL-BE", WAKE, XSalsa20
<dt>Hash Functions<dd>
	SHA1, SHA224, SHA256, SHA384, SHA512, \ref SHA3 "SHA-3", Tiger, Whirlpool, RIPEMD160, RIPEMD320, RIPEMD128, RIPEMD256, Weak::MD2, Weak::MD4, Weak::MD5
<dt>Non-Cryptographic Checksums<dd>
	CRC32, Adler32
<dt>Message Authentication Codes<dd>
	VMAC, HMAC, CBC_MAC, CMAC, DMAC, TTMAC, \ref GCM "GCM (GMAC)"
<dt>Random Number Generators<dd>
	NullRNG(), LC_RNG, RandomPool, BlockingRng, NonblockingRng, AutoSeededRandomPool, AutoSeededX917RNG,
	\ref MersenneTwister "MersenneTwister (MT19937 and MT19937-AR)", RDRAND, RDSEED
<dt>Key Derivation and Password-based Cryptography<dd>
	HKDF, \ref PKCS12_PBKDF "PBKDF (PKCS #12)", \ref PKCS5_PBKDF1 "PBKDF-1 (PKCS #5)", \ref PKCS5_PBKDF2_HMAC "PBKDF-2/HMAC (PKCS #5)"
<dt>Public Key Cryptosystems<dd>
	DLIES, ECIES, LUCES, RSAES, RabinES, LUC_IES
<dt>Public Key Signature Schemes<dd>
	DSA2, GDSA, ECDSA, NR, ECNR, LUCSS, RSASS, RSASS_ISO, RabinSS, RWSS, ESIGN
<dt>Key Agreement<dd>
	DH, DH2, MQV, ECDH, ECMQV, XTR_DH
<dt>Algebraic Structures<dd>
	Integer, PolynomialMod2, PolynomialOver, RingOfPolynomialsOver,
	ModularArithmetic, MontgomeryRepresentation, GFP2_ONB, GF2NP, GF256, GF2_32, EC2N, ECP
<dt>Secret Sharing and Information Dispersal<dd>
	SecretSharing, SecretRecovery, InformationDispersal, InformationRecovery
<dt>Compression<dd>
	Deflator, Inflator, Gzip, Gunzip, ZlibCompressor, ZlibDecompressor
<dt>Input Source Classes<dd>
	StringSource, ArraySource, FileSource, SocketSource, WindowsPipeSource, RandomNumberSource
<dt>Output Sink Classes<dd>
	StringSinkTemplate, StringSink, ArraySink, FileSink, SocketSink, WindowsPipeSink, RandomNumberSink
<dt>Filter Wrappers<dd>
	StreamTransformationFilter, HashFilter, HashVerificationFilter, SignerFilter, SignatureVerificationFilter
<dt>Binary to Text Encoders and Decoders<dd>
	HexEncoder, HexDecoder, Base64Encoder, Base64Decoder, Base64URLEncoder, Base64URLDecoder, Base32Encoder, Base32Decoder
<dt>Wrappers for OS features<dd>
	Timer, Socket, WindowsHandle, ThreadLocalStorage, ThreadUserTimer
<dt>FIPS 140 validated cryptography<dd>
	fips140.h
</dl>

In the DLL version of Crypto++, only the following implementation class are available.
<dl>
<dt>Block Ciphers<dd>
	AES, \ref DES_EDE2 "2-key Triple-DES", \ref DES_EDE3 "3-key Triple-DES", SKIPJACK
<dt>Cipher Modes (replace template parameter BC with one of the block ciphers above)<dd>
	\ref ECB_Mode "ECB_Mode<BC>", \ref CTR_Mode "CTR_Mode<BC>", \ref CBC_Mode "CBC_Mode<BC>", \ref CFB_FIPS_Mode "CFB_FIPS_Mode<BC>", \ref OFB_Mode "OFB_Mode<BC>", \ref GCM "GCM<AES>"
<dt>Hash Functions<dd>
	SHA1, SHA224, SHA256, SHA384, SHA512
<dt>Public Key Signature Schemes (replace template parameter H with one of the hash functions above)<dd>
	RSASS\<PKCS1v15, H\>, RSASS\<PSS, H\>, RSASS_ISO\<H\>, RWSS\<P1363_EMSA2, H\>, DSA, ECDSA\<ECP, H\>, ECDSA\<EC2N, H\>
<dt>Message Authentication Codes (replace template parameter H with one of the hash functions above)<dd>
	HMAC\<H\>, CBC_MAC\<DES_EDE2\>, CBC_MAC\<DES_EDE3\>, GCM\<AES\>
<dt>Random Number Generators<dd>
	DefaultAutoSeededRNG (AutoSeededX917RNG\<AES\>)
<dt>Key Agreement<dd>
	DH, DH2
<dt>Public Key Cryptosystems<dd>
	RSAES\<OAEP\<SHA1\> \>
</dl>

<p>This reference manual is a work in progress. Some classes are lack detailed descriptions.
<p>Click <a href="CryptoPPRef.zip">here</a> to download a zip archive containing this manual.
<p>Thanks to Ryan Phillips for providing the Doxygen configuration file
and getting us started on the manual.
*/

#ifndef CRYPTOPP_CRYPTLIB_H
#define CRYPTOPP_CRYPTLIB_H

#include "config.h"
#include "stdcpp.h"

#if CRYPTOPP_MSC_VERSION
# pragma warning(push)
# pragma warning(disable: 4127 4189 4702)
#endif

NAMESPACE_BEGIN(CryptoPP)

// forward declarations
class Integer;
class RandomNumberGenerator;
class BufferedTransformation;

//! \brief Specifies a direction for a cipher to operate
enum CipherDir {ENCRYPTION, DECRYPTION};

//! \brief Represents infinite time
const unsigned long INFINITE_TIME = ULONG_MAX;

// VC60 workaround: using enums as template parameters causes problems
//! \brief Converts a typename to an enumerated value
template <typename ENUM_TYPE, int VALUE>
struct EnumToType
{
	static ENUM_TYPE ToEnum() {return (ENUM_TYPE)VALUE;}
};

//! \brief Provides the byte ordering
enum ByteOrder {LITTLE_ENDIAN_ORDER = 0, BIG_ENDIAN_ORDER = 1};
//! \brief Provides a constant for LittleEndian
typedef EnumToType<ByteOrder, LITTLE_ENDIAN_ORDER> LittleEndian;
//! \brief Provides a constant for BigEndian
typedef EnumToType<ByteOrder, BIG_ENDIAN_ORDER> BigEndian;

//! \class Exception
//! \brief Base class for all exceptions thrown by the library
//! \details All library exceptions directly or indirectly inherit from the Exception class.
//!   The Exception class itself inherits from std::exception. The library does not use
//!   std::runtime_error derived classes.
class CRYPTOPP_DLL Exception : public std::exception
{
public:
	//! \enum ErrorType
	//! \brief Error types or categories
	enum ErrorType {
		//! \brief A method was called which was not implemented
		NOT_IMPLEMENTED,
		//! \brief An invalid argument was detected
		INVALID_ARGUMENT,
		//! \brief BufferedTransformation received a Flush(true) signal but can't flush buffers
		CANNOT_FLUSH,
		//! \brief Data integerity check, such as CRC or MAC, failed
		DATA_INTEGRITY_CHECK_FAILED,
		//! \brief Input data was received that did not conform to expected format
		INVALID_DATA_FORMAT,
		//! \brief Error reading from input device or writing to output device
		IO_ERROR,
		//! \brief Some other error occurred not belonging to other categories
		OTHER_ERROR
	};

	//! \brief Construct a new  Exception
	explicit Exception(ErrorType errorType, const std::string &s) : m_errorType(errorType), m_what(s) {}
	virtual ~Exception() throw() {}
	
	//! \brief Retrieves a C-string describing the exception
	const char *what() const throw() {return (m_what.c_str());}
	//! \brief Retrieves a  string describing the exception
	const std::string &GetWhat() const {return m_what;}
	//! \brief Sets the error  string for the exception
	void SetWhat(const std::string &s) {m_what = s;}
	//! \brief Retrieves the error type for the exception
	ErrorType GetErrorType() const {return m_errorType;}
	//! \brief Sets the error type for the exceptions
	void SetErrorType(ErrorType errorType) {m_errorType = errorType;}

private:
	ErrorType m_errorType;
	std::string m_what;
};

//! \brief An invalid argument was detected
class CRYPTOPP_DLL InvalidArgument : public Exception
{
public:
	explicit InvalidArgument(const std::string &s) : Exception(INVALID_ARGUMENT, s) {}
};

//! \brief Input data was received that did not conform to expected format
class CRYPTOPP_DLL InvalidDataFormat : public Exception
{
public:
	explicit InvalidDataFormat(const std::string &s) : Exception(INVALID_DATA_FORMAT, s) {}
};

//! \brief A decryption filter encountered invalid ciphertext
class CRYPTOPP_DLL InvalidCiphertext : public InvalidDataFormat
{
public:
	explicit InvalidCiphertext(const std::string &s) : InvalidDataFormat(s) {}
};

//! \brief A method was called which was not implemented
class CRYPTOPP_DLL NotImplemented : public Exception
{
public:
	explicit NotImplemented(const std::string &s) : Exception(NOT_IMPLEMENTED, s) {}
};

//! \brief Flush(true) was called but it can't completely flush its buffers
class CRYPTOPP_DLL CannotFlush : public Exception
{
public:
	explicit CannotFlush(const std::string &s) : Exception(CANNOT_FLUSH, s) {}
};

//! \brief The operating system reported an error
class CRYPTOPP_DLL OS_Error : public Exception
{
public:
	OS_Error(ErrorType errorType, const std::string &s, const std::string& operation, int errorCode)
		: Exception(errorType, s), m_operation(operation), m_errorCode(errorCode) {}
	~OS_Error() throw() {}

	//! \brief Retrieve the operating system API that reported the error
	const std::string & GetOperation() const {return m_operation;}
	//! \brief Retrieve the error code returned by the operating system
	int GetErrorCode() const {return m_errorCode;}

protected:
	std::string m_operation;
	int m_errorCode;
};

//! \class DecodingResult
//! \brief Returns a decoding results
struct CRYPTOPP_DLL DecodingResult
{
	//! \brief Constructs a DecodingResult
	//! \details isValidCoding is initialized to  false and messageLength is initialized to 0.
	explicit DecodingResult() : isValidCoding(false), messageLength(0) {}
	//! \brief Constructs a DecodingResult
	//! \param len the message length
	//! \details isValidCoding is initialized to  true.
	explicit DecodingResult(size_t len) : isValidCoding(true), messageLength(len) {}

	//! \brief Compare two DecodingResult
	//! \param rhs the other DecodingResult
	//! \returns true if both isValidCoding and messageLength are equal, false otherwise
	bool operator==(const DecodingResult &rhs) const {return isValidCoding == rhs.isValidCoding && messageLength == rhs.messageLength;}
	//! \brief Compare two DecodingResult
	//! \param rhs the other DecodingResult
	//! \returns true if either isValidCoding or messageLength is \a not equal, false otherwise
	//! \details Returns <tt>!operator==(rhs)</tt>.
	bool operator!=(const DecodingResult &rhs) const {return !operator==(rhs);}

	//! \brief Flag to indicate the decoding is valid
	bool isValidCoding;
	//! \brief Recovered message length if isValidCoding is true, undefined otherwise
	size_t messageLength;

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	operator size_t() const {return isValidCoding ? messageLength : 0;}
#endif
};

//! \class NameValuePairs
//! \brief Interface for retrieving values given their names
//! \details This class is used to safely pass a variable number of arbitrarily typed arguments to functions
//!   and to read values from keys and crypto parameters.
//! \details To obtain an object that implements NameValuePairs for the purpose of parameter
//!   passing, use the MakeParameters() function.
//! \details To get a value from NameValuePairs, you need to know the name and the type of the value. 
//!   Call GetValueNames() on a NameValuePairs object to obtain a list of value names that it supports.
//!   then look at the Name namespace documentation to see what the type of each value is, or
//!   alternatively, call GetIntValue() with the value name, and if the type is not int, a
//!   ValueTypeMismatch exception will be thrown and you can get the actual type from the exception object.
class CRYPTOPP_NO_VTABLE NameValuePairs
{
public:
	virtual ~NameValuePairs() {}

	//! \class ValueTypeMismatch
	//! \brief Thrown when an unexpected type is encountered
	//! \details Exception thrown when trying to retrieve a value using a different type than expected
	class CRYPTOPP_DLL ValueTypeMismatch : public InvalidArgument
	{
	public:
		//! \brief Construct a ValueTypeMismatch
		//! \param name the name of the value
		//! \param stored the \a actual type of the value stored
		//! \param retrieving the \a presumed type of the value retrieved
		ValueTypeMismatch(const std::string &name, const std::type_info &stored, const std::type_info &retrieving)
			: InvalidArgument("NameValuePairs: type mismatch for '" + name + "', stored '" + stored.name() + "', trying to retrieve '" + retrieving.name() + "'")
			, m_stored(stored), m_retrieving(retrieving) {}

		//! \brief Provides the stored type
		//! \returns the C++ mangled name of the type
		const std::type_info & GetStoredTypeInfo() const {return m_stored;}
		
		//! \brief Provides the retrieveing type
		//! \returns the C++ mangled name of the type
		const std::type_info & GetRetrievingTypeInfo() const {return m_retrieving;}

	private:
		const std::type_info &m_stored;
		const std::type_info &m_retrieving;
	};

	//! \brief Get a copy of this object or subobject
	//! \tparam T class or type
	//! \param object reference to a variable that receives the value
	template <class T>
	bool GetThisObject(T &object) const
	{
		return GetValue((std::string("ThisObject:")+typeid(T).name()).c_str(), object);
	}

	//! \brief Get a pointer to this object
	//! \tparam T class or type
	//! \param ptr reference to a pointer to a variable that receives the value
	template <class T>
	bool GetThisPointer(T *&ptr) const
	{
		return GetValue((std::string("ThisPointer:")+typeid(T).name()).c_str(), ptr);
	}

	//! \brief Get a named value
	//! \tparam T class or type
	//! \param name the name of the object or value to retrieve
	//! \param value reference to a variable that receives the value
	//! \returns  true if the value was retrieved,  false otherwise
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	template <class T>
	bool GetValue(const char *name, T &value) const
	{
		return GetVoidValue(name, typeid(T), &value);
	}

	//! \brief Get a named value
	//! \tparam T class or type
	//! \param name the name of the object or value to retrieve
	//! \param defaultValue the default value of the class or type if it does not exist
	//! \returns the object or value
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	template <class T>
	T GetValueWithDefault(const char *name, T defaultValue) const
	{
		T value;
		bool result = GetValue(name, value);
		// No assert... this recovers from failure
		if (result) {return value;}
		return defaultValue;
	}

	//! \brief Get a list of value names that can be retrieved
	//! \returns a list of names available to retrieve
	//! \details the items in the list are delimited with a colon.
	CRYPTOPP_DLL std::string GetValueNames() const
		{std::string result; GetValue("ValueNames", result); return result;}

	//! \brief Get a named value with type int
	//! \param name the name of the value to retrieve
	//! \param value the value retrieved upon success
	//! \returns true if an int value was retrieved, false otherwise
	//! \details GetIntValue() is used to ensure we don't accidentally try to get an
	//!   unsigned int or some other type when we mean int (which is the most common case)
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	CRYPTOPP_DLL bool GetIntValue(const char *name, int &value) const
		{return GetValue(name, value);}

	//! \brief Get a named value with type int, with default
	//! \param name the name of the value to retrieve
	//! \param defaultValue the default value if the name does not exist
	//! \returns the value retrieved on success or the default value
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	CRYPTOPP_DLL int GetIntValueWithDefault(const char *name, int defaultValue) const
		{return GetValueWithDefault(name, defaultValue);}

	//! \brief Ensures an expected name and type is present
	//! \param name the name of the value
	//! \param stored the type that was stored for the name
	//! \param retrieving the type that is being retrieved for the name
	//! \throws ValueTypeMismatch
	//! \details ThrowIfTypeMismatch() effectively performs a type safety check.
	//!    stored and  retrieving are C++ mangled names for the type.
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	CRYPTOPP_DLL static void CRYPTOPP_API ThrowIfTypeMismatch(const char *name, const std::type_info &stored, const std::type_info &retrieving)
		{if (stored != retrieving) throw ValueTypeMismatch(name, stored, retrieving);}

	//! \brief Retrieves a required name/value pair
	//! \tparam T class or type
	//! \param className the name of the class
	//! \param name the name of the value
	//! \param value reference to a variable to receive the value
	//! \throws InvalidArgument
	//! \details GetRequiredParameter() throws  InvalidArgument if the  name
	//!   is not present or not of the expected type  T.
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	template <class T>
	void GetRequiredParameter(const char *className, const char *name, T &value) const
	{
		if (!GetValue(name, value))
			throw InvalidArgument(std::string(className) + ": missing required parameter '" + name + "'");
	}

	//! \brief Retrieves a required name/value pair
	//! \param className the name of the class
	//! \param name the name of the value
	//! \param value reference to a variable to receive the value
	//! \throws InvalidArgument
	//! \details GetRequiredParameter() throws  InvalidArgument if the  name
	//!   is not present or not of the expected type  T.
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	CRYPTOPP_DLL void GetRequiredIntParameter(const char *className, const char *name, int &value) const
	{
		if (!GetIntValue(name, value))
			throw InvalidArgument(std::string(className) + ": missing required parameter '" + name + "'");
	}
	
	//! \brief Get a named value
	//! \param name the name of the object or value to retrieve
	//! \param valueType reference to a variable that receives the value
	//! \param pValue void pointer to a variable that receives the value
	//! \returns  true if the value was retrieved,  false otherwise
	//! \details GetVoidValue() retrives the value of  name if it exists.
	//! \note  GetVoidValue() is an internal function and should be implemented
	//!   by derived classes. Users should use one of the other functions instead.
	//! \sa GetValue(), GetValueWithDefault(), GetIntValue(), GetIntValueWithDefault(),
	//!   GetRequiredParameter() and GetRequiredIntParameter()
	CRYPTOPP_DLL virtual bool GetVoidValue(const char *name, const std::type_info &valueType, void *pValue) const =0;
};

#if CRYPTOPP_DOXYGEN_PROCESSING

//! \brief Namespace containing value name definitions.
//! \details Name is part of the CryptoPP namespace.
//! \details The semantics of value names, types are:
//! <pre>
//!     ThisObject:ClassName (ClassName, copy of this object or a subobject)
//!     ThisPointer:ClassName (const ClassName *, pointer to this object or a subobject)
//! </pre>
DOCUMENTED_NAMESPACE_BEGIN(Name)
// more names defined in argnames.h
DOCUMENTED_NAMESPACE_END

//! \brief Namespace containing weak and wounded algorithms.
//! \details Weak is part of the CryptoPP namespace. Schemes and algorithms are moved into  Weak
//!   when their security level is reduced to an unacceptable value by contemporary standards.
DOCUMENTED_NAMESPACE_BEGIN(Weak)
// weak and wounded algorithms
DOCUMENTED_NAMESPACE_END
#endif

//! \brief An empty set of name-value pairs
extern CRYPTOPP_DLL const NameValuePairs &g_nullNameValuePairs;

// ********************************************************

//! \class Clonable
//! \brief Interface for cloning objects
//! \note this is \a not implemented by most classes
//! \sa ClonableImpl, NotCopyable
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE Clonable
{
public:
	virtual ~Clonable() {}
	
	//! \brief Copies  this object
	//! \returns a copy of this object
	//! \throws NotImplemented
	//! \note this is \a not implemented by most classes
	//! \sa  NotCopyable
	virtual Clonable* Clone() const {throw NotImplemented("Clone() is not implemented yet.");}	// TODO: make this =0
};

//! \class Algorithm
//! \brief Interface for all crypto algorithms
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE Algorithm : public Clonable
{
public:
	//! \brief Interface for all crypto algorithms
	//! \param checkSelfTestStatus determines whether the object can proceed if the self
	//!   tests have not been run or failed.
	//! \details When FIPS 140-2 compliance is enabled and checkSelfTestStatus == true,
	//!   this constructor throws SelfTestFailure if the self test hasn't been run or fails.
	//! \details FIPS 140-2 compliance is disabled by default. It is only used by certain
	//!   versions of the library when the library is built as a DLL on Windows. Also see
	//!    CRYPTOPP_ENABLE_COMPLIANCE_WITH_FIPS_140_2 in config.h.
	Algorithm(bool checkSelfTestStatus = true);
	
	//! \brief Provides the name of this algorithm
	//! \returns the standard algorithm name
	//! \details The standard algorithm name can be a name like \a AES or \a AES/GCM. Some algorithms
	//!   do not have standard names yet. For example, there is no standard algorithm name for
	//!   Shoup's  ECIES.
	//! \note  AlgorithmName is not universally implemented yet
	virtual std::string AlgorithmName() const {return "unknown";}
	
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~Algorithm() {}
#endif
};

//! \class SimpleKeyingInterface
//! \brief Interface for algorithms that take byte strings as keys
//! \sa FixedKeyLength(), VariableKeyLength(), SameKeyLengthAs(), SimpleKeyingInterfaceImpl()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE SimpleKeyingInterface
{
public:
	virtual ~SimpleKeyingInterface() {}

	//! \brief Returns smallest valid key length in bytes
	virtual size_t MinKeyLength() const =0;
	//! \brief Returns largest valid key length in bytes
	virtual size_t MaxKeyLength() const =0;
	//! \brief Returns default (recommended) key length in bytes
	virtual size_t DefaultKeyLength() const =0;

	//! \brief
	//! \param n the desired keylength
	//! \returns the smallest valid key length in bytes that is greater than or equal to <tt>min(n, GetMaxKeyLength())</tt>
	virtual size_t GetValidKeyLength(size_t n) const =0;

	//! \brief Returns whether  keylength is a valid key length
	//! \param keylength the requested keylength
	//! \returns true if keylength is valid, false otherwise
	//! \details Internally the function calls GetValidKeyLength()
	virtual bool IsValidKeyLength(size_t keylength) const
		{return keylength == GetValidKeyLength(keylength);}

	//! \brief Sets or reset the key of this object
	//! \param key the key to use when keying the object
	//! \param length the size of the key, in bytes
	//! \param params additional initialization parameters that cannot be passed
	//!   directly through the constructor
	virtual void SetKey(const byte *key, size_t length, const NameValuePairs &params = g_nullNameValuePairs);

	//! \brief Sets or reset the key of this object
	//! \param key the key to use when keying the object
	//! \param length the size of the key, in bytes
	//! \param rounds the number of rounds to apply the transformation function,
	//!    if applicable
	//! \details SetKeyWithRounds() calls SetKey() with a NameValuePairs
	//!   object that only specifies rounds. rounds is an integer parameter,
	//!   and <tt>-1</tt> means use the default number of rounds.
	void SetKeyWithRounds(const byte *key, size_t length, int rounds);

	//! \brief Sets or reset the key of this object
	//! \param key the key to use when keying the object
	//! \param length the size of the key, in bytes
	//! \param iv the intiialization vector to use when keying the object
	//! \param ivLength the size of the iv, in bytes
	//! \details SetKeyWithIV() calls SetKey() with a NameValuePairs
	//!   that only specifies IV. The IV is a byte buffer with size ivLength.
	//!   ivLength is an integer parameter, and <tt>-1</tt> means use IVSize().
	void SetKeyWithIV(const byte *key, size_t length, const byte *iv, size_t ivLength);

	//! \brief Sets or reset the key of this object
	//! \param key the key to use when keying the object
	//! \param length the size of the key, in bytes
	//! \param iv the intiialization vector to use when keying the object
	//! \details SetKeyWithIV() calls SetKey() with a NameValuePairs() object
	//!   that only specifies iv. iv is a byte buffer, and it must have
	//!   a size IVSize().
	void SetKeyWithIV(const byte *key, size_t length, const byte *iv)
		{SetKeyWithIV(key, length, iv, IVSize());}

	//! \brief Secure IVs requirements as enumerated values.
	//! \details Provides secure IV requirements as a monotomically increasing enumerated values. Requirements can be
	//!    compared using less than (&lt;) and greater than (&gt;). For example, <tt>UNIQUE_IV &lt; RANDOM_IV</tt>
	//!    and <tt>UNPREDICTABLE_RANDOM_IV &gt; RANDOM_IV</tt>.
	//! \sa IsResynchronizable(), CanUseRandomIVs(), CanUsePredictableIVs(), CanUseStructuredIVs()
	enum IV_Requirement {
		//! \brief The IV must be unique
		UNIQUE_IV = 0,
		//! \brief The IV must be random and possibly predictable
		RANDOM_IV,
		//! \brief The IV must be random and unpredictable
		UNPREDICTABLE_RANDOM_IV,
		//! \brief The IV is set by the object
		INTERNALLY_GENERATED_IV,
		//! \brief The object does not use an IV
		NOT_RESYNCHRONIZABLE
	};

	//! \brief Minimal requirement for secure IVs
	//! \returns the secure IV requirement of the algorithm
	virtual IV_Requirement IVRequirement() const =0;

	//! \brief Determines if the object can be resynchronized
	//! \returns true if the object can be resynchronized (i.e. supports initialization vectors), false otherwise
	//! \note If this function returns true, and no IV is passed to SetKey() and <tt>CanUseStructuredIVs()==true</tt>,
	//!   an IV of all 0's will be assumed.
	bool IsResynchronizable() const {return IVRequirement() < NOT_RESYNCHRONIZABLE;}
	
	//! \brief Determines if the object can use random IVs
	//! \returns true if the object can use random IVs (in addition to ones returned by GetNextIV), false otherwise
	bool CanUseRandomIVs() const {return IVRequirement() <= UNPREDICTABLE_RANDOM_IV;}
	
	//! \brief Determines if the object can use random but possibly predictable IVs
	//! \returns true if the object can use random but possibly predictable IVs (in addition to ones returned by
	//!    GetNextIV), false otherwise
	bool CanUsePredictableIVs() const {return IVRequirement() <= RANDOM_IV;}
	
	//! \brief Determines if the object can use structured IVs
	//! returns whether the object can use structured IVs, for example a counter (in addition to ones returned by
	//!    GetNextIV), false otherwise
	bool CanUseStructuredIVs() const {return IVRequirement() <= UNIQUE_IV;}

	//! \brief Returns length of the IV accepted by this object
	//! \returns the size of an IV, in bytes
	//! \throws NotImplemented() if the object does not support resynchronization
	//! \details The default implementation throws NotImplemented
	virtual unsigned int IVSize() const
		{throw NotImplemented(GetAlgorithm().AlgorithmName() + ": this object doesn't support resynchronization");}

	//! \brief Provides the default size of an IV
	//! \returns default length of IVs accepted by this object, in bytes
	unsigned int DefaultIVLength() const {return IVSize();}
	
	//! \brief Provides the minimum size of an IV
	//! \returns minimal length of IVs accepted by this object, in bytes
	//! \throws NotImplemented() if the object does not support resynchronization
	virtual unsigned int MinIVLength() const {return IVSize();}
	
	//! \brief Provides the maximum size of an IV
	//! \returns maximal length of IVs accepted by this object, in bytes
	//! \throws NotImplemented() if the object does not support resynchronization
	virtual unsigned int MaxIVLength() const {return IVSize();}

	//! \brief Resynchronize with an IV
	//! \param iv the initialization vector
	//! \param ivLength the size of the initialization vector, in bytes
	//! \details Resynchronize() resynchronizes with an IV provided by the caller. <tt>ivLength=-1</tt> means use IVSize().
	//! \throws NotImplemented() if the object does not support resynchronization
	virtual void Resynchronize(const byte *iv, int ivLength=-1) {
		CRYPTOPP_UNUSED(iv); CRYPTOPP_UNUSED(ivLength);
		throw NotImplemented(GetAlgorithm().AlgorithmName() + ": this object doesn't support resynchronization");
	}

	//! \brief Retrieves a secure IV for the next message
	//! \param rng a RandomNumberGenerator to produce keying material
	//! \param iv a block of bytes to receive the IV
	//! \details The IV must be at least IVSize() in length.
	//! \details This method should be called after you finish encrypting one message and are ready
	//!    to start the next one. After calling it, you must call SetKey() or Resynchronize().
	//!    before using this object again.
	//! \details Internally, the base class implementation calls RandomNumberGenerator's GenerateBlock()
	//! \note This method is not implemented on decryption objects.
	virtual void GetNextIV(RandomNumberGenerator &rng, byte *iv);

protected:
	//! \brief Returns the base class  Algorithm
	//! \returns the base class  Algorithm
	virtual const Algorithm & GetAlgorithm() const =0;
	
	//! \brief Sets the key for this object without performing parameter validation
	//! \param key a byte buffer used to key the cipher
	//! \param length the length of the byte buffer
	//! \param params additional parameters passed as  NameValuePairs
	//! \details key must be at least  DEFAULT_KEYLENGTH in length.
	virtual void UncheckedSetKey(const byte *key, unsigned int length, const NameValuePairs &params) =0;
	
	//! \brief Validates the key length
	//! \param length the size of the keying material, in bytes
	//! \throws InvalidKeyLength if the key length is invalid
	void ThrowIfInvalidKeyLength(size_t length);
	
	//! \brief Validates the object
	//! \throws InvalidArgument if the IV is present
	//! \details Internally, the default implementation calls  IsResynchronizable() and throws 
	//!    InvalidArgument if the function returns  true.
	//! \note called when no IV is passed
	void ThrowIfResynchronizable();
	
	//! \brief Validates the IV
	//! \param iv the IV with a length of  IVSize, in bytes
	//! \throws InvalidArgument on failure
	//! \details Internally, the default implementation checks the  iv. If  iv is not  NULL,
	//!   then the function succeeds. If  iv is  NULL, then  IVRequirement is checked against
	//!    UNPREDICTABLE_RANDOM_IV. If  IVRequirement is  UNPREDICTABLE_RANDOM_IV, then
	//!   then the function succeeds. Otherwise, an exception is thrown.
	void ThrowIfInvalidIV(const byte *iv);
	
	//! \brief Validates the IV length
	//! \param length the size of an IV, in bytes
	//! \throws InvalidArgument if the number of  rounds are invalid
	size_t ThrowIfInvalidIVLength(int length);
	
	//! \brief retrieves and validates the IV
	//! \param params  NameValuePairs with the IV supplied as a  ConstByteArrayParameter
	//! \param size the length of the IV, in bytes
	//! \returns a pointer to the first byte of the  IV
	//! \throws InvalidArgument if the number of  rounds are invalid
	const byte * GetIVAndThrowIfInvalid(const NameValuePairs &params, size_t &size);
	
	//! \brief Validates the key length
	//! \param length the size of the keying material, in bytes
	inline void AssertValidKeyLength(size_t length) const
		{CRYPTOPP_UNUSED(length); assert(IsValidKeyLength(length));}
};

//! \brief Interface for the data processing part of block ciphers
//! \details Classes derived from BlockTransformation are block ciphers
//!   in ECB mode (for example the DES::Encryption class), which are stateless.
//!   These classes should not be used directly, but only in combination with
//!   a mode class (see CipherModeDocumentation in modes.h).
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE BlockTransformation : public Algorithm
{
public:
	//! \brief Encrypt or decrypt a block
	//! \param inBlock the input message before processing
	//! \param outBlock the output message after processing
	//! \param xorBlock an optional XOR mask
	//! \details ProcessAndXorBlock encrypts or decrypts inBlock, xor with xorBlock, and write to outBlock.
	//! \details The size of the block is determined by the block cipher and its documentation. Use
	//!     BLOCKSIZE at compile time, or BlockSize() at runtime.
	//! \note The message can be transformed in-place, or the buffers must \a not overlap
	//! \sa FixedBlockSize, BlockCipherFinal from seckey.h and BlockSize()
	virtual void ProcessAndXorBlock(const byte *inBlock, const byte *xorBlock, byte *outBlock) const =0;

	//! \brief Encrypt or decrypt a block
	//! \param inBlock the input message before processing
	//! \param outBlock the output message after processing
	//! \details ProcessBlock encrypts or decrypts inBlock and write to outBlock.
	//! \details The size of the block is determined by the block cipher and its documentation.
	//!    Use  BLOCKSIZE at compile time, or BlockSize() at runtime.
	//! \sa FixedBlockSize, BlockCipherFinal from seckey.h and BlockSize()
	//! \note The message can be transformed in-place, or the buffers must \a not overlap
	void ProcessBlock(const byte *inBlock, byte *outBlock) const
		{ProcessAndXorBlock(inBlock, NULL, outBlock);}

	//! \brief Encrypt or decrypt a block in place
	//! \param inoutBlock the input message before processing
	//! \details ProcessBlock encrypts or decrypts inoutBlock in-place.
	//! \details The size of the block is determined by the block cipher and its documentation.
	//!    Use BLOCKSIZE at compile time, or BlockSize() at runtime.
	//! \sa FixedBlockSize, BlockCipherFinal from seckey.h and BlockSize()
	void ProcessBlock(byte *inoutBlock) const
		{ProcessAndXorBlock(inoutBlock, NULL, inoutBlock);}

	//! Provides the block size of the cipher
	//! \returns the block size of the cipher, in bytes
	virtual unsigned int BlockSize() const =0;

	//! \brief Provides input and output data alignment for optimal performance.
	//! \returns the input data alignment that provides optimal performance
	virtual unsigned int OptimalDataAlignment() const;

	//! returns true if this is a permutation (i.e. there is an inverse transformation)
	virtual bool IsPermutation() const {return true;}

	//! \brief Determines if the cipher is being operated in its forward direction
	//! \returns  true if DIR is ENCRYPTION,  false otherwise
	//! \sa IsForwardTransformation(), IsPermutation(), GetCipherDirection()
	virtual bool IsForwardTransformation() const =0;

	//! \brief Determines the number of blocks that can be processed in parallel
	//! \return the number of blocks that can be processed in parallel, for bit-slicing implementations
	//! \details Bit-slicing is often used to improve throughput and minimize timing attacks.
	virtual unsigned int OptimalNumberOfParallelBlocks() const {return 1;}

	//! \brief Bit flags that control AdvancedProcessBlocks() behavior
	enum FlagsForAdvancedProcessBlocks {
		//! \brief inBlock is a counter
		BT_InBlockIsCounter=1,
		//! \brief should not modify block pointers
		BT_DontIncrementInOutPointers=2,
		//! \brief 
		BT_XorInput=4,
		//! \brief perform the transformation in reverse
		BT_ReverseDirection=8,
		//! \brief 
		BT_AllowParallel=16};

	//! \brief Encrypt and xor multiple blocks using additional flags
	//! \param inBlocks the input message before processing
	//! \param xorBlocks an optional XOR mask
	//! \param outBlocks the output message after processing
	//! \param length the size of the blocks, in bytes
	//! \param flags additional flags to control processing
	//! \details Encrypt and xor multiple blocks according to FlagsForAdvancedProcessBlocks flags.
	//! \note If BT_InBlockIsCounter is set, then the last byte of inBlocks may be modified.
	virtual size_t AdvancedProcessBlocks(const byte *inBlocks, const byte *xorBlocks, byte *outBlocks, size_t length, word32 flags) const;

	//! \sa IsForwardTransformation(), IsPermutation(), GetCipherDirection()
	inline CipherDir GetCipherDirection() const {return IsForwardTransformation() ? ENCRYPTION : DECRYPTION;}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~BlockTransformation() {}
#endif
};

//! \class StreamTransformation
//! \brief Interface for the data processing portion of stream ciphers
//! \sa StreamTransformationFilter()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE StreamTransformation : public Algorithm
{
public:
	//! \brief Provides a reference to this object
	//! \returns A reference to this object
	//! \details Useful for passing a temporary object to a function that takes a non-const reference
	StreamTransformation& Ref() {return *this;}

	//! \brief Provides the mandatory block size of the cipher
	//! \returns The block size of the cipher if input must be processed in blocks, 1 otherwise
	virtual unsigned int MandatoryBlockSize() const {return 1;}

	//! \brief Provides the input block size most efficient for this cipher.
	//! \returns The input block size that is most efficient for the cipher
	//! \details The base class implementation returns MandatoryBlockSize().
	//! \note Optimal input length is
	//!   <tt>n * OptimalBlockSize() - GetOptimalBlockSizeUsed()</tt> for any <tt>n \> 0</tt>.
	virtual unsigned int OptimalBlockSize() const {return MandatoryBlockSize();}
	
	//! \brief Provides the number of bytes used in the current block when processing at optimal block size.
	//! \returns the number of bytes used in the current block when processing at the optimal block size
	virtual unsigned int GetOptimalBlockSizeUsed() const {return 0;}
	
	//! \brief Provides input and output data alignment for optimal performance.
	//! \returns the input data alignment that provides optimal performance
	virtual unsigned int OptimalDataAlignment() const;

	//! \brief Encrypt or decrypt an array of bytes
	//! \param outString the output byte buffer
	//! \param inString the input byte buffer
	//! \param length the size of the input and output byte buffers, in bytes
	//! \details Either <tt>inString == outString</tt>, or they must not overlap.
	virtual void ProcessData(byte *outString, const byte *inString, size_t length) =0;

	//! \brief Encrypt or decrypt the last block of data
	//! \param outString the output byte buffer
	//! \param inString the input byte buffer
	//! \param length the size of the input and output byte buffers, in bytes
	//!  ProcessLastBlock is used when the last block of data is special.
	//!   Currently the only use of this function is CBC-CTS mode.
	virtual void ProcessLastBlock(byte *outString, const byte *inString, size_t length);

	//! returns the minimum size of the last block, 0 indicating the last block is not special
	virtual unsigned int MinLastBlockSize() const {return 0;}

	//! \brief Encrypt or decrypt a string of bytes
	//! \param inoutString the string to process
	//! \param length the size of the  inoutString, in bytes
	//! \details Internally, the base class implementation calls ProcessData().
	inline void ProcessString(byte *inoutString, size_t length)
		{ProcessData(inoutString, inoutString, length);}

	//! \brief Encrypt or decrypt a string of bytes
	//! \param outString the output string to process
	//! \param inString the input string to process
	//! \param length the size of the input and output strings, in bytes
	//! \details Internally, the base class implementation calls ProcessData().
	inline void ProcessString(byte *outString, const byte *inString, size_t length)
		{ProcessData(outString, inString, length);}

	//! \brief Encrypt or decrypt a byte
	//! \param input the input byte to process
	//! \details Internally, the base class implementation calls ProcessData() with a size of 1.
	inline byte ProcessByte(byte input)
		{ProcessData(&input, &input, 1); return input;}

	//! \brief Determines whether the cipher supports random access
	//! \returns  true if the cipher supports random access,  false otherwise
	virtual bool IsRandomAccess() const =0;

	//! \brief Seek to an absolute position
	//! \param pos position to seek
	//! \throws NotImplemented
	//! \details The base class implementation throws NotImplemented. The function
	//!   asserts  IsRandomAccess() in debug builds.
	virtual void Seek(lword pos)
	{
		CRYPTOPP_UNUSED(pos);
		assert(!IsRandomAccess());
		throw NotImplemented("StreamTransformation: this object doesn't support random access");
	}

	//! \brief Determines whether the cipher is self-inverting
	//! \returns  true if the cipher is self-inverting,  false otherwise
	//! \details IsSelfInverting determines whether this transformation is 
	//!   self-inverting (e.g. xor with a keystream).
	virtual bool IsSelfInverting() const =0;

	//! \brief Determines if the cipher is being operated in its forward direction
	//! \returns  true if DIR is ENCRYPTION,  false otherwise
	//! \sa IsForwardTransformation(), IsPermutation(), GetCipherDirection()
	virtual bool IsForwardTransformation() const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~StreamTransformation() {}
#endif
};

//! \class HashTransformation
//! \brief Interface for hash functions and data processing part of MACs
//! \details HashTransformation objects are stateful. They are created in an initial state,
//!   change state as Update() is called, and return to the initial
//!   state when Final() is called. This interface allows a large message to
//!   be hashed in pieces by calling Update() on each piece followed by
//!   calling Final().
//! \sa HashFilter(), HashVerificationFilter()
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE HashTransformation : public Algorithm
{
public:
	//! \brief Provides a reference to this object
	//! \returns A reference to this object
	//! \details Useful for passing a temporary object to a function that takes a non-const reference
	HashTransformation& Ref() {return *this;}

	//! \brief Updates a hash with additional input
	//! \param input the additional input as a buffer
	//! \param length the size of the buffer, in bytes
	virtual void Update(const byte *input, size_t length) =0;

	//! \brief Request space which can be written into by the caller
	//! \param size the requested size of the buffer
	//! \details The purpose of this method is to help avoid extra memory allocations.
	//! \details size is an \a IN and \a OUT parameter and used as a hint. When the call is made,
	//!   size is the requested size of the buffer. When the call returns, size is the size of
	//!   the array returned to the caller.
	//! \details The base class implementation sets  size to 0 and returns  NULL.
	//! \note Some objects, like ArraySink, cannot create a space because its fixed. In the case of
	virtual byte * CreateUpdateSpace(size_t &size) {size=0; return NULL;}

	//! \brief Computes the hash of the current message
	//! \param digest a pointer to the buffer to receive the hash
	//! \details digest must be equal to (or greater than) DigestSize(). Final() restarts the
	//!   hash for a new message.
	virtual void Final(byte *digest)
		{TruncatedFinal(digest, DigestSize());}

	//! \brief Restart the hash
	//! \details Discards the current state, and restart for a new message
	virtual void Restart()
		{TruncatedFinal(NULL, 0);}

	//! Provides the digest size of the hash
	//! \returns the digest size of the hash.
	//! \details Calls to Final() require a buffer that is equal to (or greater than) DigestSize().
	virtual unsigned int DigestSize() const =0;

	//! Provides the tag size of the hash
	//! \returns the tag size of the hash.
	//! \details Same as DigestSize().
	unsigned int TagSize() const {return DigestSize();}
	
	//! \brief Provides the block size of the compression function
	//! \returns the block size of the compression function, in bytes
	//! \details BlockSize() will return 0 if the hash is not block based. For example,
	//!   SHA3 is a recursive hash (not an iterative hash), and it does not have a block size.
	virtual unsigned int BlockSize() const {return 0;}

	//! \brief Provides the input block size most efficient for this hash.
	//! \returns The input block size that is most efficient for the cipher
	//! \details The base class implementation returns MandatoryBlockSize().
	//! \note Optimal input length is
	//!   <tt>n * OptimalBlockSize() - GetOptimalBlockSizeUsed()</tt> for any <tt>n \> 0</tt>.
	virtual unsigned int OptimalBlockSize() const {return 1;}

	//! \brief Provides input and output data alignment for optimal performance
	//! \returns the input data alignment that provides optimal performance
	virtual unsigned int OptimalDataAlignment() const;
	
	//! \brief Updates the hash with additional input and computes the hash of the current message
	//! \param digest a pointer to the buffer to receive the hash
	//! \param input the additional input as a buffer
	//! \param length the size of the buffer, in bytes
	//! \details Use this if your input is in one piece and you don't want to call Update()
	//!   and Final() separately
	//! \details CalculateDigest() restarts the hash for the next nmessage.
	virtual void CalculateDigest(byte *digest, const byte *input, size_t length)
		{Update(input, length); Final(digest);}
	
	//! \brief Verifies the hash of the current message
	//! \param digest a pointer to the buffer of an \a existing hash
	//! \returns \p true if the existing hash matches the computed hash, \p false otherwise
	//! \throws ThrowIfInvalidTruncatedSize() if the existing hash's size exceeds DigestSize()
	//! \details Calls to Verify() require a buffer that is equal to (or greater than) DigestSize().
	//! \details Verify() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is
	//!   a constant time comparison function. digestLength cannot exceed DigestSize().
	//! \details Verify() restarts the hash for the next nmessage.
	virtual bool Verify(const byte *digest)
		{return TruncatedVerify(digest, DigestSize());}

	//! \brief Updates the hash with additional input and verifies the hash of the current message
	//! \param digest a pointer to the buffer of an \a existing hash
	//! \param input the additional input as a buffer
	//! \param length the size of the buffer, in bytes
	//! \returns \p true if the existing hash matches the computed hash, \p false otherwise
	//! \throws ThrowIfInvalidTruncatedSize() if the existing hash's size exceeds DigestSize()
	//! \details Use this if your input is in one piece and you don't want to call Update()
	//!   and Verify() separately
	//! \details VerifyDigest() performs a bitwise compare on the buffers using VerifyBufsEqual(),
	//!   which is a constant time comparison function. digestLength cannot exceed DigestSize().
	//! \details VerifyDigest() restarts the hash for the next nmessage.
	virtual bool VerifyDigest(const byte *digest, const byte *input, size_t length)
		{Update(input, length); return Verify(digest);}

	//! \brief Computes the hash of the current message
	//! \param digest a pointer to the buffer to receive the hash
	//! \param digestSize the size of the truncated digest, in bytes
	//! \details TruncatedFinal() call Final() and then copies digestSize bytes to digest
	//! \details TruncatedFinal() restarts the hash for the next message.
	virtual void TruncatedFinal(byte *digest, size_t digestSize) =0;

	//! \brief Updates the hash with additional input and computes the hash of the current message
	//! \param digest a pointer to the buffer to receive the hash
	//! \param digestSize the length of the truncated hash, in bytes
	//! \param input the additional input as a buffer
	//! \param length the size of the buffer, in bytes
	//! \details Use this if your input is in one piece and you don't want to call Update()
	//!   and CalculateDigest() separately.
	//! \details CalculateTruncatedDigest() restarts the hash for the next nmessage.
	virtual void CalculateTruncatedDigest(byte *digest, size_t digestSize, const byte *input, size_t length)
		{Update(input, length); TruncatedFinal(digest, digestSize);}

	//! \brief Verifies the hash of the current message
	//! \param digest a pointer to the buffer of an \a existing hash
	//! \param digestLength the size of the truncated hash, in bytes
	//! \returns \p true if the existing hash matches the computed hash, \p false otherwise
	//! \throws ThrowIfInvalidTruncatedSize() if digestLength exceeds DigestSize()
	//! \details TruncatedVerify() is a truncated version of Verify(). It can operate on a
	//!   buffer smaller than DigestSize(). However, digestLength cannot exceed DigestSize().
	//! \details Verify() performs a bitwise compare on the buffers using VerifyBufsEqual(), which is
	//!   a constant time comparison function. digestLength cannot exceed DigestSize().
	//! \details TruncatedVerify() restarts the hash for the next nmessage.
	virtual bool TruncatedVerify(const byte *digest, size_t digestLength);

	//! \brief Updates the hash with additional input and verifies the hash of the current message
	//! \param digest a pointer to the buffer of an \a existing hash
	//! \param digestLength the size of the truncated hash, in bytes
	//! \param input the additional input as a buffer
	//! \param length the size of the buffer, in bytes
	//! \returns \p true if the existing hash matches the computed hash, \p false otherwise
	//! \throws ThrowIfInvalidTruncatedSize() if digestLength exceeds DigestSize()
	//! \details Use this if your input is in one piece and you don't want to call Update()
	//!   and TruncatedVerify() separately.
	//! \details VerifyTruncatedDigest() is a truncated version of VerifyDigest(). It can operate
	//!   on a buffer smaller than DigestSize(). However, digestLength cannot exceed DigestSize().
	//! \details VerifyTruncatedDigest() restarts the hash for the next nmessage.
	virtual bool VerifyTruncatedDigest(const byte *digest, size_t digestLength, const byte *input, size_t length)
		{Update(input, length); return TruncatedVerify(digest, digestLength);}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~HashTransformation() {}
#endif

protected:
	//! \brief Validates a truncated digest size
	//! \param size the requested digest size
	//! \throws InvalidArgument if the algorithm's digest size cannot be truncated to the requested size
	//! \details Throws an exception when the truncated digest size is greater than DigestSize()
	void ThrowIfInvalidTruncatedSize(size_t size) const;
};

typedef HashTransformation HashFunction;

//! \brief Interface for one direction (encryption or decryption) of a block cipher
/*! \note These objects usually should not be used directly. See BlockTransformation for more details. */
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE BlockCipher : public SimpleKeyingInterface, public BlockTransformation
{
protected:
	const Algorithm & GetAlgorithm() const {return *this;}
};

//! \brief Interface for one direction (encryption or decryption) of a stream cipher or cipher mode
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE SymmetricCipher : public SimpleKeyingInterface, public StreamTransformation
{
protected:
	const Algorithm & GetAlgorithm() const {return *this;}
};

//! \brief Interface for message authentication codes
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE MessageAuthenticationCode : public SimpleKeyingInterface, public HashTransformation
{
protected:
	const Algorithm & GetAlgorithm() const {return *this;}
};

//! \brief Interface for one direction (encryption or decryption) of a stream cipher or block cipher mode with authentication
/*! The StreamTransformation part of this interface is used to encrypt/decrypt the data, and the MessageAuthenticationCode part of this
	interface is used to input additional authenticated data (AAD, which is MAC'ed but not encrypted), and to generate/verify the MAC. */
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AuthenticatedSymmetricCipher : public MessageAuthenticationCode, public StreamTransformation
{
public:
	//! this indicates that a member function was called in the wrong state, for example trying to encrypt a message before having set the key or IV
	class BadState : public Exception
	{
	public:
		explicit BadState(const std::string &name, const char *message) : Exception(OTHER_ERROR, name + ": " + message) {}
		explicit BadState(const std::string &name, const char *function, const char *state) : Exception(OTHER_ERROR, name + ": " + function + " was called before " + state) {}
	};

	//! the maximum length of AAD that can be input before the encrypted data
	virtual lword MaxHeaderLength() const =0;
	//! the maximum length of encrypted data
	virtual lword MaxMessageLength() const =0;
	//! the maximum length of AAD that can be input after the encrypted data
	virtual lword MaxFooterLength() const {return 0;}
	//! if this function returns true, SpecifyDataLengths() must be called before attempting to input data
	/*! This is the case for some schemes, such as CCM. */
	virtual bool NeedsPrespecifiedDataLengths() const {return false;}
	//! this function only needs to be called if NeedsPrespecifiedDataLengths() returns true
	void SpecifyDataLengths(lword headerLength, lword messageLength, lword footerLength=0);
	//! encrypt and generate MAC in one call. will truncate MAC if macSize < TagSize()
	virtual void EncryptAndAuthenticate(byte *ciphertext, byte *mac, size_t macSize, const byte *iv, int ivLength, const byte *header, size_t headerLength, const byte *message, size_t messageLength);
	//! decrypt and verify MAC in one call, returning true iff MAC is valid. will assume MAC is truncated if macLength < TagSize()
	virtual bool DecryptAndVerify(byte *message, const byte *mac, size_t macLength, const byte *iv, int ivLength, const byte *header, size_t headerLength, const byte *ciphertext, size_t ciphertextLength);

	// redeclare this to avoid compiler ambiguity errors
	virtual std::string AlgorithmName() const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~AuthenticatedSymmetricCipher() {}
#endif

protected:
	const Algorithm & GetAlgorithm() const
		{return *static_cast<const MessageAuthenticationCode *>(this);}
	virtual void UncheckedSpecifyDataLengths(lword headerLength, lword messageLength, lword footerLength)
		{CRYPTOPP_UNUSED(headerLength); CRYPTOPP_UNUSED(messageLength); CRYPTOPP_UNUSED(footerLength);}
};

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
typedef SymmetricCipher StreamCipher;
#endif

//! \class RandomNumberGenerator
//! \brief Interface for random number generators
//! \details The library provides a number of random number generators, from software based to hardware based generators.
//! \details All generated values are uniformly distributed over the range specified.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE RandomNumberGenerator : public Algorithm
{
public:
	//! \brief Update RNG state with additional unpredictable values
	//! \param input the entropy to add to the generator
	//! \param length the size of the input buffer 
	//! \throws NotImplemented
	//! \details A generator may or may not accept additional entropy. Call  CanIncorporateEntropy() to test for the
	//!   ability to use additional entropy.
	//! \details If a derived class does not override IncorporateEntropy(), then the base class throws
	//!   NotImplemented.
	virtual void IncorporateEntropy(const byte *input, size_t length)
	{
		CRYPTOPP_UNUSED(input); CRYPTOPP_UNUSED(length);
		throw NotImplemented("RandomNumberGenerator: IncorporateEntropy not implemented");
	}

	//! \brief Determines if a generator can accept additional entropy
	//! \returns true if IncorporateEntropy() is implemented
	virtual bool CanIncorporateEntropy() const {return false;}

	//! \brief Generate new random byte and return it
	//! \returns a random 8-bit byte
	//! \details Default implementation calls GenerateBlock() with one byte.
	//! \details All generated values are uniformly distributed over the range specified within the
	//!   the contraints of a particular generator.
	virtual byte GenerateByte();

	//! \brief Generate new random bit and return it
	//! \returns a random bit
	//! \details The default implementation calls GenerateByte() and return its lowest bit.
	//! \details All generated values are uniformly distributed over the range specified within the
	//!   the contraints of a particular generator.
	virtual unsigned int GenerateBit();

	//! \brief Generate a random 32 bit word in the range min to max, inclusive
	//! \param min the lower bound of the range
	//! \param max the upper bound of the range
	//! \returns a random 32-bit word
	//! \details The default implementation calls Crop() on the difference between max and
	//!    min, and then returns the result added to min.
	//! \details All generated values are uniformly distributed over the range specified within the
	//!   the contraints of a particular generator.
	virtual word32 GenerateWord32(word32 min=0, word32 max=0xffffffffUL);

	//! \brief Generate random array of bytes
	//! \param output the byte buffer
	//! \param size the length of the buffer, in bytes
	//! \details All generated values are uniformly distributed over the range specified within the
	//!   the contraints of a particular generator.
	//! \note A derived generator \a must override either GenerateBlock() or
	//!    GenerateIntoBufferedTransformation(). They can override both, or have one call the other.
	virtual void GenerateBlock(byte *output, size_t size);

	//! \brief Generate random bytes into a BufferedTransformation
	//! \param target the BufferedTransformation object which receives the bytes
	//! \param channel the channel on which the bytes should be pumped
	//! \param length the number of bytes to generate
	//! \details The default implementation calls GenerateBlock() and pumps the result into
	//!   the  DEFAULT_CHANNEL of the target.
	//! \details All generated values are uniformly distributed over the range specified within the
	//!   the contraints of a particular generator.
	//! \note A derived generator \a must override either GenerateBlock() or
	//!    GenerateIntoBufferedTransformation(). They can override both, or have one call the other.
	virtual void GenerateIntoBufferedTransformation(BufferedTransformation &target, const std::string &channel, lword length);

	//! \brief Generate and discard n bytes
	//! \param n the number of bytes to generate and discard
	virtual void DiscardBytes(size_t n);

	//! \brief Randomly shuffle the specified array
	//! \param begin an iterator to the first element in the array
	//! \param end an iterator beyond the last element in the array
	//! \details The resulting permutation is uniformly distributed.
	template <class IT> void Shuffle(IT begin, IT end)
	{
		// TODO: What happens if there are more than 2^32 elements?
		for (; begin != end; ++begin)
			std::iter_swap(begin, begin + GenerateWord32(0, end-begin-1));
	}
	
#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~RandomNumberGenerator() {}
#endif

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	byte GetByte() {return GenerateByte();}
	unsigned int GetBit() {return GenerateBit();}
	word32 GetLong(word32 a=0, word32 b=0xffffffffL) {return GenerateWord32(a, b);}
	word16 GetShort(word16 a=0, word16 b=0xffff) {return (word16)GenerateWord32(a, b);}
	void GetBlock(byte *output, size_t size) {GenerateBlock(output, size);}
#endif

};

//! \brief Random Number Generator that does not produce random numbers
//! \returns reference that can be passed to functions that require a RandomNumberGenerator
//! \details NullRNG() returns a reference that can be passed to functions that require a
//!   RandomNumberGenerator but don't actually use it. The NullRNG() throws NotImplemented 
//!   when a generation function is called.
//! \sa ClassNullRNG, IsProbabilistic()
CRYPTOPP_DLL RandomNumberGenerator & CRYPTOPP_API NullRNG();

//! \class WaitObjectContainer
class WaitObjectContainer;
//! \class CallStack
class CallStack;

//! \brief Interface for objects that can be waited on.
class CRYPTOPP_NO_VTABLE Waitable
{
public:
	virtual ~Waitable() {}

	//! \brief Maximum number of wait objects that this object can return
	virtual unsigned int GetMaxWaitObjectCount() const =0;

	//! \brief Retrieves waitable objects
	//! \param container the wait container to receive the references to the objects.
	//! \param callStack  CallStack object used to select waitable objects
	//! \details GetWaitObjects is usually called in one of two ways. First, it can
	//!   be called like <tt>something.GetWaitObjects(c, CallStack("my func after X", 0));</tt>.
	//!   Second, if in an outer  GetWaitObjects() method that itself takes a callStack
	//!   parameter, it can be called like
	//!   <tt>innerThing.GetWaitObjects(c, CallStack("MyClass::GetWaitObjects at X", &callStack));</tt>.
	virtual void GetWaitObjects(WaitObjectContainer &container, CallStack const& callStack) =0;

	//! wait on this object
	/*! same as creating an empty container, calling GetWaitObjects(), and calling Wait() on the container */
	bool Wait(unsigned long milliseconds, CallStack const& callStack);
};

//! \brief Default channel for BufferedTransformation
//! \details DEFAULT_CHANNEL is equal to an empty  string
extern CRYPTOPP_DLL const std::string DEFAULT_CHANNEL;

//! \brief Channel for additional authenticated data
//! \details AAD_CHANNEL is equal to "AAD"
extern CRYPTOPP_DLL const std::string AAD_CHANNEL;

//! \brief Interface for buffered transformations
//! \details BufferedTransformation is a generalization of BlockTransformation,
//!   StreamTransformation and HashTransformation.
//! \details A buffered transformation is an object that takes a stream of bytes as input (this may
//!   be done in stages), does some computation on them, and then places the result into an internal
//!   buffer for later retrieval. Any partial result already in the output buffer is not modified
//!   by further input.
//! \details If a method takes a "blocking" parameter, and you pass  false for it, then the method
//!   will return before all input has been processed if the input cannot be processed without waiting
//!   (for network buffers to become available, for example). In this case the method will return true
//!   or a non-zero integer value. When this happens you must continue to call the method with the same
//!   parameters until it returns false or zero, before calling any other method on it or attached
//!   /p BufferedTransformation. The integer return value in this case is approximately
//!   the number of bytes left to be processed, and can be used to implement a progress bar.
//! \details For functions that take a "propagation" parameter, <tt>propagation != 0</tt> means pass on
//!   the signal to attached BufferedTransformation objects, with propagation decremented at each
//!   step until it reaches <tt>0</tt>. <tt>-1</tt> means unlimited propagation.
//! \details \a All of the retrieval functions, like Get() and GetWord32(), return the actual
//!   number of bytes retrieved, which is the lesser of the request number and  MaxRetrievable().
//! \details \a Most of the input functions, like Put() and PutWord32(), return the number of
//!   bytes remaining to be processed. A 0 value means all bytes were processed, and a non-0 value
//!   means bytes remain to be processed.
//! \nosubgrouping
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE BufferedTransformation : public Algorithm, public Waitable
{
public:
	// placed up here for CW8
	static const std::string &NULL_CHANNEL;	// same as DEFAULT_CHANNEL, for backwards compatibility

	BufferedTransformation() : Algorithm(false) {}

	//! \brief Provides a reference to this object
	//! \returns A reference to this object
	//! \details Useful for passing a temporary object to a function that takes a non-const reference
	BufferedTransformation& Ref() {return *this;}

	//!	\name INPUT
	//@{

		//! \brief Input a byte for processing
		//! \param inByte the 8-bit byte (octet) to be processed.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		//! \details <tt>Put(byte)</tt> calls <tt>Put(byte*, size_t)</tt>.
		size_t Put(byte inByte, bool blocking=true)
			{return Put(&inByte, 1, blocking);}

		//! \brief Input a byte buffer for processing
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		//! \details Internally, Put() calls Put2().
		size_t Put(const byte *inString, size_t length, bool blocking=true)
			{return Put2(inString, length, 0, blocking);}

		//! Input a 16-bit word for processing.
		//! \param value the 16-bit value to be processed
		//! \param order the  ByteOrder in which the word should be processed
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		size_t PutWord16(word16 value, ByteOrder order=BIG_ENDIAN_ORDER, bool blocking=true);
		
		//! Input a 32-bit word for processing.
		//! \param value the 32-bit value to be processed.
		//! \param order the  ByteOrder in which the word should be processed.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		size_t PutWord32(word32 value, ByteOrder order=BIG_ENDIAN_ORDER, bool blocking=true);

		//! \brief Request space which can be written into by the caller
		//! \param size the requested size of the buffer
		//! \details The purpose of this method is to help avoid extra memory allocations.
		//! \details size is an \a IN and \a OUT parameter and used as a hint. When the call is made,
		//!    size is the requested size of the buffer. When the call returns,  size is the size of
		//!   the array returned to the caller.
		//! \details The base class implementation sets  size to 0 and returns  NULL.
		//! \note Some objects, like ArraySink, cannot create a space because its fixed. In the case of
		//! an ArraySink, the pointer to the array is returned and the  size is remaining size.
		virtual byte * CreatePutSpace(size_t &size)
			{size=0; return NULL;}

		//! \brief Determines whether input can be modifed by the callee
		//! \returns true if input can be modified, false otherwise
		//! \details The base class implementation returns  false.
		virtual bool CanModifyInput() const
			{return false;}

		//! \brief Input multiple bytes that may be modified by callee.
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param blocking specifies whether the object should block when processing input
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed
		size_t PutModifiable(byte *inString, size_t length, bool blocking=true)
			{return PutModifiable2(inString, length, 0, blocking);}

		//! \brief Signals the end of messages to the object
		//! \param propagation the number of attached transformations the  MessageEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		bool MessageEnd(int propagation=-1, bool blocking=true)
			{return !!Put2(NULL, 0, propagation < 0 ? -1 : propagation+1, blocking);}

		//! \brief Input multiple bytes for processing and signal the end of a message
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param propagation the number of attached transformations the  MessageEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		//! \details Internally, PutMessageEnd() calls Put2() with a modified  propagation to
		//!    ensure all attached transformations finish processing the message.
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		size_t PutMessageEnd(const byte *inString, size_t length, int propagation=-1, bool blocking=true)
			{return Put2(inString, length, propagation < 0 ? -1 : propagation+1, blocking);}

		//! \brief Input multiple bytes for processing
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param messageEnd means how many filters to signal MessageEnd() to, including this one
		//! \param blocking specifies whether the object should block when processing input
		//! \details Derived classes must implement Put2().
		virtual size_t Put2(const byte *inString, size_t length, int messageEnd, bool blocking) =0;

		//! \brief Input multiple bytes that may be modified by callee.
		//! \param inString the byte buffer to process.
		//! \param length the size of the string, in bytes.
		//! \param messageEnd means how many filters to signal MessageEnd() to, including this one.
		//! \param blocking specifies whether the object should block when processing input.
		//! \details Internally, PutModifiable2() calls Put2().
		virtual size_t PutModifiable2(byte *inString, size_t length, int messageEnd, bool blocking)
			{return Put2(inString, length, messageEnd, blocking);}

		//! \class BlockingInputOnly
		//! \brief Exception thrown by objects that have \a not implemented nonblocking input processing
		//! \details BlockingInputOnly inherits from NotImplemented
		struct BlockingInputOnly : public NotImplemented
			{BlockingInputOnly(const std::string &s) : NotImplemented(s + ": Nonblocking input is not implemented by this object.") {}};
	//@}

	//!	\name WAITING
	//@{
		//! \brief Retrieves the maximum number of waitable objects
		unsigned int GetMaxWaitObjectCount() const;

		//! \brief Retrieves waitable objects
		//! \param container the wait container to receive the references to the objects
		//! \param callStack  CallStack object used to select waitable objects
		//! \details GetWaitObjects is usually called in one of two ways. First, it can
		//!    be called like <tt>something.GetWaitObjects(c, CallStack("my func after X", 0));</tt>.
		//!    Second, if in an outer  GetWaitObjects() method that itself takes a callStack
		//!    parameter, it can be called like
		//!    <tt>innerThing.GetWaitObjects(c, CallStack("MyClass::GetWaitObjects at X", &callStack));</tt>.
		void GetWaitObjects(WaitObjectContainer &container, CallStack const& callStack);
	//@} // WAITING

	//!	\name SIGNALS
	//@{
		
		//! \brief Initialize or reinitialize this object, without signal propagation
		//! \param parameters a set of NameValuePairs to initialize this object
		//! \throws NotImplemented
		//! \details IsolatedInitialize() is used to initialize or reinitialize an object using a variable
		//!   number of  arbitrarily typed arguments. The function avoids the need for multiple constuctors providing
		//!   all possible combintations of configurable parameters.
		//! \details IsolatedInitialize() does not call Initialize() on attached transformations. If initialization
		//!   should be propagated, then use the Initialize() function.
		//! \details If a derived class does not override IsolatedInitialize(), then the base class throws
		//!   NotImplemented.
		virtual void IsolatedInitialize(const NameValuePairs &parameters) {
			CRYPTOPP_UNUSED(parameters);
			throw NotImplemented("BufferedTransformation: this object can't be reinitialized");
		}
		
		//! \brief Flushes data buffered by this object, without signal propagation
		//! \param hardFlush indicates whether all data should be flushed
		//! \param blocking specifies whether the object should block when processing input
		//! \note  hardFlush must be used with care
		virtual bool IsolatedFlush(bool hardFlush, bool blocking) =0;
		
		//! \brief Marks the end of a series of messages, without signal propagation
		//! \param blocking specifies whether the object should block when completing the processing on
		//!    the current series of messages
		virtual bool IsolatedMessageSeriesEnd(bool blocking)
			{CRYPTOPP_UNUSED(blocking); return false;}

		//! \brief Initialize or reinitialize this object, with signal propagation
		//! \param parameters a set of NameValuePairs to initialize or reinitialize this object
		//! \param propagation the number of attached transformations the Initialize() signal should be passed
		//! \details Initialize() is used to initialize or reinitialize an object using a variable number of 
		//!   arbitrarily typed arguments. The function avoids the need for multiple constuctors providing
		//!   all possible combintations of configurable parameters.
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		virtual void Initialize(const NameValuePairs &parameters=g_nullNameValuePairs, int propagation=-1);

		//! \brief Flush buffered input and/or output, with signal propagation
		//! \param hardFlush is used to indicate whether all data should be flushed
		//! \param propagation the number of attached transformations the  Flush() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		//! \note Hard flushes must be used with care. It means try to process and output everything, even if
		//!   there may not be enough data to complete the action. For example, hard flushing a  HexDecoder
		//!   would cause an error if you do it after inputing an odd number of hex encoded characters.
		//! \note For some types of filters, like  ZlibDecompressor, hard flushes can only
		//!   be done at "synchronization points". These synchronization points are positions in the data
		//!   stream that are created by hard flushes on the corresponding reverse filters, in this
		//!   example ZlibCompressor. This is useful when zlib compressed data is moved across a
		//!   network in packets and compression state is preserved across packets, as in the SSH2 protocol.
		virtual bool Flush(bool hardFlush, int propagation=-1, bool blocking=true);

		//! \brief Marks the end of a series of messages, with signal propagation
		//! \param propagation the number of attached transformations the  MessageSeriesEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \details Each object that receives the signal will perform its processing, decrement
		//!    propagation, and then pass the signal on to attached transformations if the value is not 0.
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		//! \note There should be a  MessageEnd() immediately before MessageSeriesEnd().
		virtual bool MessageSeriesEnd(int propagation=-1, bool blocking=true);

		//! \brief Set propagation of automatically generated and transferred signals
		//! \param propagation then new value 
		//! \details Setting propagation to <tt>0</tt> means do not automaticly generate signals. Setting
		//!    propagation to <tt>-1</tt> means unlimited propagation.
		virtual void SetAutoSignalPropagation(int propagation)
			{CRYPTOPP_UNUSED(propagation);}

		//! \brief Retrieve automatic signal propagation value
		virtual int GetAutoSignalPropagation() const {return 0;}
public:

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
		void Close() {MessageEnd();}
#endif
	//@}

	//!	\name RETRIEVAL OF ONE MESSAGE
	//@{

		//! \brief Provides the number of bytes ready for retrieval
		//! \returns the number of bytes ready for retrieval
		//! \details All retrieval functions return the actual number of bytes retrieved, which is
		//!   the lesser of the request number and  MaxRetrievable()
		virtual lword MaxRetrievable() const;

		//! \brief Determines whether bytes are ready for retrieval
		//! \returns  true if bytes are available for retrieval, false otherwise
		virtual bool AnyRetrievable() const;

		//! \brief Retrieve a 8-bit byte
		//! \param outByte the 8-bit value to be retrieved
		//! \returns the number of bytes consumed during the call.
		//! \details Use the return value of  Get to detect short reads.
		virtual size_t Get(byte &outByte);
		
		//! \brief Retrieve a block of bytes
		//! \param outString a block of bytes
		//! \param getMax the number of bytes to  Get
		//! \returns the number of bytes consumed during the call.
		//! \details Use the return value of  Get to detect short reads.
		virtual size_t Get(byte *outString, size_t getMax);

		//! \brief Peek a 8-bit byte
		//! \param outByte the 8-bit value to be retrieved
		//! \returns the number of bytes read during the call.
		//! \details Peek does not remove bytes from the object. Use the return value of
		//!     Get to detect short reads.
		virtual size_t Peek(byte &outByte) const;
		
		//! \brief Peek a block of bytes
		//! \param outString a block of bytes
		//! \param peekMax the number of bytes to  Peek
		//! \returns the number of bytes read during the call.
		//! \details Peek does not remove bytes from the object. Use the return value of
		//!     Get to detect short reads.
		virtual size_t Peek(byte *outString, size_t peekMax) const;

		//! \brief Retrieve a 16-bit word
		//! \param value the 16-bit value to be retrieved
		//! \param order the  ByteOrder in which the word should be retrieved
		//! \returns the number of bytes consumed during the call.
		//! \details Use the return value of  GetWord16 to detect short reads.
		size_t GetWord16(word16 &value, ByteOrder order=BIG_ENDIAN_ORDER);

		//! \brief Retrieve a 32-bit word
		//! \param value the 32-bit value to be retrieved
		//! \param order the  ByteOrder in which the word should be retrieved
		//! \returns the number of bytes consumed during the call.
		//! \details Use the return value of  GetWord16 to detect short reads.
		size_t GetWord32(word32 &value, ByteOrder order=BIG_ENDIAN_ORDER);

		//! \brief Peek a 16-bit word
		//! \param value the 16-bit value to be retrieved
		//! \param order the  ByteOrder in which the word should be retrieved
		//! \returns the number of bytes consumed during the call.
		//! \details Peek does not consume bytes in the stream. Use the return value
		//!    of  GetWord16 to detect short reads.
		size_t PeekWord16(word16 &value, ByteOrder order=BIG_ENDIAN_ORDER) const;

		//! \brief Peek a 32-bit word
		//! \param value the 32-bit value to be retrieved
		//! \param order the  ByteOrder in which the word should be retrieved
		//! \returns the number of bytes consumed during the call.
		//! \details Peek does not consume bytes in the stream. Use the return value
		//!    of  GetWord16 to detect short reads.
		size_t PeekWord32(word32 &value, ByteOrder order=BIG_ENDIAN_ORDER) const;

		//! move transferMax bytes of the buffered output to target as input
		
		//! \brief Transfer bytes from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param transferMax the number of bytes to transfer
		//! \param channel the channel on which the transfer should occur
		//! \returns the number of bytes transferred during the call.
		//! \details TransferTo removes bytes from this object and moves them to the destination.
		//! \details The function always returns  transferMax. If an accurate count is needed, then use  TransferTo2.
		lword TransferTo(BufferedTransformation &target, lword transferMax=LWORD_MAX, const std::string &channel=DEFAULT_CHANNEL)
			{TransferTo2(target, transferMax, channel); return transferMax;}

		//! \brief Discard  skipMax bytes from the output buffer
		//! \param skipMax the number of bytes to discard
		//! \details Skip always returns  skipMax.
		virtual lword Skip(lword skipMax=LWORD_MAX);

		//! copy copyMax bytes of the buffered output to target as input
		
		//! \brief Copy bytes from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param copyMax the number of bytes to copy
		//! \param channel the channel on which the transfer should occur
		//! \returns the number of bytes copied during the call.
		//! \details CopyTo copies bytes from this object to the destination. The bytes are not removed from this object.
		//! \details The function always returns  copyMax. If an accurate count is needed, then use  CopyRangeTo2.
		lword CopyTo(BufferedTransformation &target, lword copyMax=LWORD_MAX, const std::string &channel=DEFAULT_CHANNEL) const
			{return CopyRangeTo(target, 0, copyMax, channel);}
		
		//! \brief Copy bytes from this object using an index to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param position the 0-based index of the byte stream to begin the copying
		//! \param copyMax the number of bytes to copy
		//! \param channel the channel on which the transfer should occur
		//! \returns the number of bytes copied during the call.
		//! \details CopyTo copies bytes from this object to the destination. The bytes remain in this
		//!   object. Copying begins at the index position in the current stream, and not from an absolute
		//!   position in the stream.
		//! \details The function returns the new position in the stream after transferring the bytes starting at the index.
		lword CopyRangeTo(BufferedTransformation &target, lword position, lword copyMax=LWORD_MAX, const std::string &channel=DEFAULT_CHANNEL) const
			{lword i = position; CopyRangeTo2(target, i, i+copyMax, channel); return i-position;}

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
		unsigned long MaxRetrieveable() const {return MaxRetrievable();}
#endif
	//@}

	//!	\name RETRIEVAL OF MULTIPLE MESSAGES
	//@{

		//! \brief Provides the number of bytes ready for retrieval
		//! \returns the number of bytes ready for retrieval
		virtual lword TotalBytesRetrievable() const;

		//! \brief Provides the number of meesages processed by this object
		//! \returns the number of meesages processed by this object
		//! \details NumberOfMessages returns number of times  MessageEnd() has been
		//!    received minus messages retrieved or skipped
		virtual unsigned int NumberOfMessages() const;

		//! \brief Determines if any messages are available for retrieval
		//! \returns  true if <tt>NumberOfMessages() &gt; 0</tt>,  false otherwise
		//! \details AnyMessages returns true if <tt>NumberOfMessages() &gt; 0</tt>
		virtual bool AnyMessages() const;

		//! \brief Start retrieving the next message
		//! \returns true if a message is ready for retrieval
		//! \details GetNextMessage() returns true if a message is ready for retrieval; false
		//!   if no more messages exist or this message is not completely retrieved.
		virtual bool GetNextMessage();

		//! \brief Skip a number of meessages
		//! \returns 0 if the requested number of messages was skipped, non-0 otherwise
		//! \details SkipMessages() skips count number of messages. If there is an AttachedTransformation()
		//!   then SkipMessages() is called on the attached transformation. If there is no attached
		//!   transformation, then count number of messages are sent to TheBitBucket() using TransferMessagesTo().
		virtual unsigned int SkipMessages(unsigned int count=UINT_MAX);

		//! \brief Transfer messages from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param count the number of messages to transfer
		//! \param channel the channel on which the transfer should occur
		//! \returns the number of bytes that remain in the current transfer block (i.e., bytes not transferred)
		//! \details TransferMessagesTo2 removes messages from this object and moves them to the destination.
		//!   If all bytes are not transferred for a message, then processing stops and the number of remaining
		//!   bytes is returned. TransferMessagesTo() does not proceed to the next message.
		//! \details A return value of 0 indicates all messages were successfully transferred.
		unsigned int TransferMessagesTo(BufferedTransformation &target, unsigned int count=UINT_MAX, const std::string &channel=DEFAULT_CHANNEL)
			{TransferMessagesTo2(target, count, channel); return count;}

		//! \brief Copies messages from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param count the number of messages to transfer
		//! \param channel the channel on which the transfer should occur
		//! \returns the number of bytes that remain in the current transfer block (i.e., bytes not transferred)
		//! \details CopyMessagesTo copies messages from this object and copies them to the destination.
		//!   If all bytes are not transferred for a message, then processing stops and the number of remaining
		//!   bytes is returned. CopyMessagesTo() does not proceed to the next message.
		//! \details A return value of 0 indicates all messages were successfully copied.
		unsigned int CopyMessagesTo(BufferedTransformation &target, unsigned int count=UINT_MAX, const std::string &channel=DEFAULT_CHANNEL) const;

		//!
		virtual void SkipAll();
		//!
		void TransferAllTo(BufferedTransformation &target, const std::string &channel=DEFAULT_CHANNEL)
			{TransferAllTo2(target, channel);}
		//!
		void CopyAllTo(BufferedTransformation &target, const std::string &channel=DEFAULT_CHANNEL) const;

		virtual bool GetNextMessageSeries() {return false;}
		virtual unsigned int NumberOfMessagesInThisSeries() const {return NumberOfMessages();}
		virtual unsigned int NumberOfMessageSeries() const {return 0;}
	//@}

	//!	\name NON-BLOCKING TRANSFER OF OUTPUT
	//@{
		
		// upon return, byteCount contains number of bytes that have finished being transfered,
		// and returns the number of bytes left in the current transfer block
		
		//! \brief Transfer bytes from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param byteCount the number of bytes to transfer
		//! \param channel the channel on which the transfer should occur
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the transfer block (i.e., bytes not transferred)
		//! \details TransferTo removes bytes from this object and moves them to the destination.
		//!   Transfer begins at the index position in the current stream, and not from an absolute
		//!   position in the stream.
		//! \details byteCount is an \a IN and \a OUT parameter. When the call is made,
		//!    byteCount is the requested size of the transfer. When the call returns,  byteCount is
		//!   the number of bytes that were transferred.
		virtual size_t TransferTo2(BufferedTransformation &target, lword &byteCount, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true) =0;
		
		// upon return, begin contains the start position of data yet to be finished copying,
		// and returns the number of bytes left in the current transfer block
	
		//! \brief Copy bytes from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param begin the 0-based index of the first byte to copy in the stream
		//! \param end the 0-based index of the last byte to copy in the stream
		//! \param channel the channel on which the transfer should occur
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the copy block (i.e., bytes not copied)
		//! \details CopyRangeTo2 copies bytes from this object to the destination. The bytes are not
		//!   removed from this object. Copying begins at the index position in the current stream, and
		//!   not from an absolute position in the stream.
		//! \details begin is an \a IN and \a OUT parameter. When the call is made,  begin is the
		//!   starting position of the copy. When the call returns,  begin is the position of the first
		//!   byte that was \a not copied (which may be different tahn  end).  begin can be used for
		//!   subsequent calls to  CopyRangeTo2.
		virtual size_t CopyRangeTo2(BufferedTransformation &target, lword &begin, lword end=LWORD_MAX, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true) const =0;
		
		// upon return, messageCount contains number of messages that have finished being transfered,
		// and returns the number of bytes left in the current transfer block

		//! \brief Transfer messages from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param messageCount the number of messages to transfer
		//! \param channel the channel on which the transfer should occur
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the current transfer block (i.e., bytes not transferred)
		//! \details TransferMessagesTo2 removes messages from this object and moves them to the destination.
		size_t TransferMessagesTo2(BufferedTransformation &target, unsigned int &messageCount, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true);
		
		// returns the number of bytes left in the current transfer block
		
		//! \brief Transfer all bytes from this object to another BufferedTransformation
		//! \param target the destination BufferedTransformation
		//! \param channel the channel on which the transfer should occur
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the current transfer block (i.e., bytes not transferred)
		//! \details TransferMessagesTo2 removes messages from this object and moves them to the destination.
		size_t TransferAllTo2(BufferedTransformation &target, const std::string &channel=DEFAULT_CHANNEL, bool blocking=true);
	//@}

	//!	\name CHANNELS
	//@{
		//! \brief Exception thrown when a filter does not support named channels
		struct NoChannelSupport : public NotImplemented
			{NoChannelSupport(const std::string &name) : NotImplemented(name + ": this object doesn't support multiple channels") {}};
		//! \brief Exception thrown when a filter does not recognize a named channel
		struct InvalidChannelName : public InvalidArgument
			{InvalidChannelName(const std::string &name, const std::string &channel) : InvalidArgument(name + ": unexpected channel name \"" + channel + "\"") {}};

		//! \brief Input a byte for processing on a channel
		//! \param channel the channel to process the data.
		//! \param inByte the 8-bit byte (octet) to be processed.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		size_t ChannelPut(const std::string &channel, byte inByte, bool blocking=true)
			{return ChannelPut(channel, &inByte, 1, blocking);}

		//! \brief Input a byte buffer for processing on a channel
		//! \param channel the channel to process the data
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param blocking specifies whether the object should block when processing input
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		size_t ChannelPut(const std::string &channel, const byte *inString, size_t length, bool blocking=true)
			{return ChannelPut2(channel, inString, length, 0, blocking);}

		//! \brief Input multiple bytes that may be modified by callee on a channel
		//! \param channel the channel to process the data.
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param blocking specifies whether the object should block when processing input
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		size_t ChannelPutModifiable(const std::string &channel, byte *inString, size_t length, bool blocking=true)
			{return ChannelPutModifiable2(channel, inString, length, 0, blocking);}

		//! \brief Input a 16-bit word for processing on a channel.
		//! \param channel the channel to process the data.
		//! \param value the 16-bit value to be processed.
		//! \param order the  ByteOrder in which the word should be processed.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		size_t ChannelPutWord16(const std::string &channel, word16 value, ByteOrder order=BIG_ENDIAN_ORDER, bool blocking=true);
		
		//! \brief Input a 32-bit word for processing on a channel.
		//! \param channel the channel to process the data.
		//! \param value the 32-bit value to be processed.
		//! \param order the  ByteOrder in which the word should be processed.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		size_t ChannelPutWord32(const std::string &channel, word32 value, ByteOrder order=BIG_ENDIAN_ORDER, bool blocking=true);

		//! \brief Signal the end of a message
		//! \param channel the channel to process the data.
		//! \param propagation the number of attached transformations the  ChannelMessageEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \returns 0 indicates all bytes were processed during the call. Non-0 indicates the
		//!   number of bytes that were \a not processed.
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		bool ChannelMessageEnd(const std::string &channel, int propagation=-1, bool blocking=true)
			{return !!ChannelPut2(channel, NULL, 0, propagation < 0 ? -1 : propagation+1, blocking);}
		
		//! \brief Input multiple bytes for processing and signal the end of a message
		//! \param channel the channel to process the data.
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param propagation the number of attached transformations the ChannelPutMessageEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		size_t ChannelPutMessageEnd(const std::string &channel, const byte *inString, size_t length, int propagation=-1, bool blocking=true)
			{return ChannelPut2(channel, inString, length, propagation < 0 ? -1 : propagation+1, blocking);}

		//! \brief Request space which can be written into by the caller
		//! \param channel the channel to process the data
		//! \param size the requested size of the buffer
		//! \returns a pointer to a memroy block with length size
		//! \details The purpose of this method is to help avoid extra memory allocations.
		//! \details size is an \a IN and \a OUT parameter and used as a hint. When the call is made,
		//!    size is the requested size of the buffer. When the call returns,  size is the size of
		//!   the array returned to the caller.
		//! \details The base class implementation sets size to 0 and returns NULL.
		//! \note Some objects, like ArraySink(), cannot create a space because its fixed. In the case of
		//! an ArraySink(), the pointer to the array is returned and the size is remaining size.
		virtual byte * ChannelCreatePutSpace(const std::string &channel, size_t &size);

		//! \brief Input multiple bytes for processing on a channel.
		//! \param channel the channel to process the data.
		//! \param inString the byte buffer to process.
		//! \param length the size of the string, in bytes.
		//! \param messageEnd means how many filters to signal MessageEnd() to, including this one.
		//! \param blocking specifies whether the object should block when processing input.
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		virtual size_t ChannelPut2(const std::string &channel, const byte *inString, size_t length, int messageEnd, bool blocking);
		
		//! \brief Input multiple bytes that may be modified by callee on a channel
		//! \param channel the channel to process the data
		//! \param inString the byte buffer to process
		//! \param length the size of the string, in bytes
		//! \param messageEnd means how many filters to signal MessageEnd() to, including this one
		//! \param blocking specifies whether the object should block when processing input
		//! \returns the number of bytes that remain in the block (i.e., bytes not processed)
		virtual size_t ChannelPutModifiable2(const std::string &channel, byte *inString, size_t length, int messageEnd, bool blocking);

		//! \brief Flush buffered input and/or output on a channel
		//! \param channel the channel to flush the data
		//! \param hardFlush is used to indicate whether all data should be flushed
		//! \param propagation the number of attached transformations the  ChannelFlush() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \returns true of the Flush was successful
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		virtual bool ChannelFlush(const std::string &channel, bool hardFlush, int propagation=-1, bool blocking=true);

		//! \brief Marks the end of a series of messages on a channel
		//! \param channel the channel to signal the end of a series of messages
		//! \param propagation the number of attached transformations the  ChannelMessageSeriesEnd() signal should be passed
		//! \param blocking specifies whether the object should block when processing input
		//! \details Each object that receives the signal will perform its processing, decrement
		//!     propagation, and then pass the signal on to attached transformations if the value is not 0.
		//! \details propagation count includes this object. Setting propagation to <tt>1</tt> means this
		//!   object only. Setting propagation to <tt>-1</tt> means unlimited propagation.
		//! \note There should be a  MessageEnd() immediately before MessageSeriesEnd().
		virtual bool ChannelMessageSeriesEnd(const std::string &channel, int propagation=-1, bool blocking=true);

		//! \brief Sets the default retrieval channel
		//! \param channel the channel to signal the end of a series of messages
		//! \note this function may not be implemented in all objects that should support it.
		virtual void SetRetrievalChannel(const std::string &channel);
	//@}

	//!	\name ATTACHMENT
	/*! Some BufferedTransformation objects (e.g. Filter objects)
		allow other BufferedTransformation objects to be attached. When
		this is done, the first object instead of buffering its output,
		sends that output to the attached object as input. The entire
		attachment chain is deleted when the anchor object is destructed.
	*/
	//@{
		//! \brief Determines whether the object allows attachment
		//! \returns true if the object allows an attachment, false otherwise
		//! \details Sources and  Filters will return  true, while  Sinks and other objects will return  false.
		virtual bool Attachable() {return false;}
		
		//! \brief Returns the object immediately attached to this object
		//! \returns the attached transformation
		//! \details AttachedTransformation() returns NULL if there is no attachment. The non-const
		//!   version of AttachedTransformation() always returns NULL.
		virtual BufferedTransformation *AttachedTransformation() {assert(!Attachable()); return 0;}
		
		//! \brief Returns the object immediately attached to this object
		//! \returns the attached transformation
		//! \details AttachedTransformation() returns NULL if there is no attachment. The non-const
		//!   version of AttachedTransformation() always returns NULL.
		virtual const BufferedTransformation *AttachedTransformation() const
			{return const_cast<BufferedTransformation *>(this)->AttachedTransformation();}

		//! \brief Delete the current attachment chain and attach a new one
		//! \param newAttachment the new BufferedTransformation to attach
		//! \throws NotImplemented
		//! \details Detach delete the current attachment chain and replace it with an optional  newAttachment
		//! \details If a derived class does not override  Detach, then the base class throws
		//!   NotImplemented.
		virtual void Detach(BufferedTransformation *newAttachment = 0) {
			CRYPTOPP_UNUSED(newAttachment); assert(!Attachable());
			throw NotImplemented("BufferedTransformation: this object is not attachable");
		}
		
		//! \brief Add newAttachment to the end of attachment chain
		//! \param newAttachment the attachment to add to the end of the chain
		virtual void Attach(BufferedTransformation *newAttachment);
	//@}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~BufferedTransformation() {}
#endif

protected:
	//! \brief Decrements the propagation count while clamping at 0
	//! \returns the decremented  propagation or 0
	static int DecrementPropagation(int propagation)
		{return propagation != 0 ? propagation - 1 : 0;}

private:
	byte m_buf[4];	// for ChannelPutWord16 and ChannelPutWord32, to ensure buffer isn't deallocated before non-blocking operation completes
};

//! \brief An input discarding BufferedTransformation
//! \returns a reference to a BufferedTransformation object that discards all input
CRYPTOPP_DLL BufferedTransformation & TheBitBucket();

//! \class CryptoMaterial
//! \brief Interface for crypto material, such as public and private keys, and crypto parameters
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE CryptoMaterial : public NameValuePairs
{
public:
	//! exception thrown when invalid crypto material is detected
	class CRYPTOPP_DLL InvalidMaterial : public InvalidDataFormat
	{
	public:
		explicit InvalidMaterial(const std::string &s) : InvalidDataFormat(s) {}
	};

	//! \brief Assign values to this object
	/*! \details This function can be used to create a public key from a private key. */
	virtual void AssignFrom(const NameValuePairs &source) =0;

	//! \brief Check this object for errors
	//! \param rng a RandomNumberGenerator for objects which use randomized testing
	//! \param level the level of thoroughness
	//! \returns  true if the tests succeed,  false otherwise
	//! \details There are four levels of thoroughness:
	//!   <ul>
	//!   <li>0 - using this object won't cause a crash or exception
	//!   <li>1 - this object will probably function, and encrypt, sign, other operations correctly
	//!   <li>2 - ensure this object will function correctly, and perform reasonable security checks
	//!   <li>3 - perform reasonable security checks, and do checks that may take a long time
	//!   </ul>
	//! \details Level 0 does not require a  RandomNumberGenerator. A  NullRNG() can be used for level 0.
	//! \details Level 1 may not check for weak keys and such.
	//! \details Levels 2 and 3 are recommended.
	virtual bool Validate(RandomNumberGenerator &rng, unsigned int level) const =0;

	//! \brief Check this object for errors
	//! \param rng a RandomNumberGenerator for objects which use randomized testing
	//! \param level the level of thoroughness
	//! \throws InvalidMaterial
	//! \details Internally,  ThrowIfInvalid() calls  Validate() and throws  InvalidMaterial if validation fails.
	virtual void ThrowIfInvalid(RandomNumberGenerator &rng, unsigned int level) const
		{if (!Validate(rng, level)) throw InvalidMaterial("CryptoMaterial: this object contains invalid values");}

	//! \brief Saves a key to a BufferedTransformation
	//! \param bt the destination BufferedTransformation
	//! \throws NotImplemented
	//! \details Save writes the material to a BufferedTransformation.
	//! \details If the material is a key, then the key is written with ASN.1 DER encoding. The key
	//!   includes an object identifier with an algorthm id, like a  subjectPublicKeyInfo.
	//! \details A "raw" key without the "key info" can be saved using a key's  DEREncode method.
	//! \details If a derived class does not override  Save, then the base class throws
	//!   NotImplemented.
	virtual void Save(BufferedTransformation &bt) const
		{CRYPTOPP_UNUSED(bt); throw NotImplemented("CryptoMaterial: this object does not support saving");}

	//! \brief Loads a key from a BufferedTransformation
	//! \param bt the source BufferedTransformation
	//! \throws KeyingErr
	//! \details Load attempts to read material from a BufferedTransformation. If the
	//!   material is a key that was generated outside the library, then the following
	//!   usually applies:
	//!   <ul>
	//!   <li>the key should be ASN.1 BER encoded
	//!   <li>the key should be a "key info"
	//!   </ul>
	//! \details "key info" means the key should have an object identifier with an algorthm id,
	//!   like a  subjectPublicKeyInfo.
	//! \details To read a "raw" key without the "key info", then call the key's  BERDecode method.
	//! \note  Load generally does not check that the key is valid. Call Validate(), if needed.
	virtual void Load(BufferedTransformation &bt)
		{CRYPTOPP_UNUSED(bt); throw NotImplemented("CryptoMaterial: this object does not support loading");}

	//! \brief Determines whether the object supports precomputation
	//! \returns true if the object supports precomputation, false otherwise
	virtual bool SupportsPrecomputation() const {return false;}

	//! \brief Perform precomputation
	//! \param precomputationStorage the suggested number of objects for the precompute table
	//! \throws NotImplemented
	//! \details The exact semantics of  Precompute() varies, but it typically means calculate
	//!   a table of  n objects that can be used later to speed up computation.
	//! \details If a derived class does not override  Precompute, then the base class throws
	//!   NotImplemented.
	virtual void Precompute(unsigned int precomputationStorage) {
		CRYPTOPP_UNUSED(precomputationStorage); assert(!SupportsPrecomputation());
		throw NotImplemented("CryptoMaterial: this object does not support precomputation");
	}

	//! retrieve previously saved precomputation
	virtual void LoadPrecomputation(BufferedTransformation &storedPrecomputation)
		{CRYPTOPP_UNUSED(storedPrecomputation); assert(!SupportsPrecomputation()); throw NotImplemented("CryptoMaterial: this object does not support precomputation");}
	//! save precomputation for later use
	virtual void SavePrecomputation(BufferedTransformation &storedPrecomputation) const
		{CRYPTOPP_UNUSED(storedPrecomputation); assert(!SupportsPrecomputation()); throw NotImplemented("CryptoMaterial: this object does not support precomputation");}

	// for internal library use
	void DoQuickSanityCheck() const	{ThrowIfInvalid(NullRNG(), 0);}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~CryptoMaterial() {}
#endif

#if (defined(__SUNPRO_CC) && __SUNPRO_CC < 0x590)
	// Sun Studio 11/CC 5.8 workaround: it generates incorrect code when casting to an empty virtual base class
	char m_sunCCworkaround;
#endif
};

//! \class GeneratableCryptoMaterial
//! \brief Interface for generatable crypto material, such as private keys and crypto parameters
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE GeneratableCryptoMaterial : virtual public CryptoMaterial
{
public:

	//! \brief Generate a random key or crypto parameters
	//! \param rng a RandomNumberGenerator to produce keying material
	//! \param params additional initialization parameters
	//! \throws KeyingErr if a key can't be generated or algorithm parameters are invalid
	//! \details If a derived class does not override  GenerateRandom, then the base class throws
	//!    NotImplemented.
	virtual void GenerateRandom(RandomNumberGenerator &rng, const NameValuePairs &params = g_nullNameValuePairs) {
		CRYPTOPP_UNUSED(rng); CRYPTOPP_UNUSED(params);
		throw NotImplemented("GeneratableCryptoMaterial: this object does not support key/parameter generation");
	}

	//! \brief Generate a random key or crypto parameters
	//! \param rng a RandomNumberGenerator to produce keying material
	//! \param keySize the size of the key, in bits
	//! \throws KeyingErr if a key can't be generated or algorithm parameters are invalid	
	//! \details GenerateRandomWithKeySize calls  GenerateRandom with a  NameValuePairs
	//!    object with only "KeySize"
	void GenerateRandomWithKeySize(RandomNumberGenerator &rng, unsigned int keySize);

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~GeneratableCryptoMaterial() {}
#endif
};

//! \brief Interface for public keys
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PublicKey : virtual public CryptoMaterial
{
};

//! \brief Interface for private keys
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PrivateKey : public GeneratableCryptoMaterial
{
};

//! \brief Interface for crypto prameters
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE CryptoParameters : public GeneratableCryptoMaterial
{
};

//! \brief Interface for asymmetric algorithms
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AsymmetricAlgorithm : public Algorithm
{
public:
	//! \brief Retrieves a reference to CryptoMaterial
	//! \returns a reference to the crypto material used by this object
	virtual CryptoMaterial & AccessMaterial() =0;
	
	//! \brief Retrieves a reference to CryptoMaterial
	//! \returns a const reference to the crypto material used by this object
	virtual const CryptoMaterial & GetMaterial() const =0;

	//! \brief Loads this object from a BufferedTransformation
	//! \param bt a BufferedTransformation object
	//! \deprecated for backwards compatibility, calls <tt>AccessMaterial().Load(bt)</tt>
	void BERDecode(BufferedTransformation &bt)
		{AccessMaterial().Load(bt);}
	
	//! \brief Saves this object to a BufferedTransformation
	//! \param bt a BufferedTransformation object
	//! \deprecated for backwards compatibility, calls GetMaterial().Save(bt)
	void DEREncode(BufferedTransformation &bt) const
		{GetMaterial().Save(bt);}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~AsymmetricAlgorithm() {}
#endif
};

//! \brief Interface for asymmetric algorithms using public keys
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PublicKeyAlgorithm : public AsymmetricAlgorithm
{
public:
	// VC60 workaround: no co-variant return type
	CryptoMaterial & AccessMaterial()
		{return AccessPublicKey();}
	const CryptoMaterial & GetMaterial() const
		{return GetPublicKey();}

	virtual PublicKey & AccessPublicKey() =0;
	virtual const PublicKey & GetPublicKey() const
		{return const_cast<PublicKeyAlgorithm *>(this)->AccessPublicKey();}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PublicKeyAlgorithm() {}
#endif
};

//! \brief Interface for asymmetric algorithms using private keys
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PrivateKeyAlgorithm : public AsymmetricAlgorithm
{
public:
	CryptoMaterial & AccessMaterial() {return AccessPrivateKey();}
	const CryptoMaterial & GetMaterial() const {return GetPrivateKey();}

	virtual PrivateKey & AccessPrivateKey() =0;
	virtual const PrivateKey & GetPrivateKey() const {return const_cast<PrivateKeyAlgorithm *>(this)->AccessPrivateKey();}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PrivateKeyAlgorithm() {}
#endif
};

//! \brief Interface for key agreement algorithms
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE KeyAgreementAlgorithm : public AsymmetricAlgorithm
{
public:
	CryptoMaterial & AccessMaterial() {return AccessCryptoParameters();}
	const CryptoMaterial & GetMaterial() const {return GetCryptoParameters();}

	virtual CryptoParameters & AccessCryptoParameters() =0;
	virtual const CryptoParameters & GetCryptoParameters() const {return const_cast<KeyAgreementAlgorithm *>(this)->AccessCryptoParameters();}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~KeyAgreementAlgorithm() {}
#endif
};

//! \brief Interface for public-key encryptors and decryptors
//! \details This class provides an interface common to encryptors and decryptors
//!   for querying their plaintext and ciphertext lengths.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_CryptoSystem
{
public:
	virtual ~PK_CryptoSystem() {}

	//! \brief Provides the maximum length of plaintext for a given ciphertext length
	//! \returns the maximum size of the plaintext, in bytes
	//! \details This function returns 0 if ciphertextLength is not valid (too long or too short).
	virtual size_t MaxPlaintextLength(size_t ciphertextLength) const =0;

	//! \brief Calculate the length of ciphertext given length of plaintext
	//! \returns the maximum size of the ciphertext, in bytes
	//! \details This function returns 0 if plaintextLength is not valid (too long).
	virtual size_t CiphertextLength(size_t plaintextLength) const =0;

	//! \brief Determines whether this object supports the use of a named parameter 
	//! \param name the name of the parameter
	//! \returns true if the parameter name is supported, false otherwise
	//! \details Some possible parameter names: EncodingParameters(), KeyDerivationParameters()
	//!   and others Parameters listed in argnames.h
	virtual bool ParameterSupported(const char *name) const =0;

	//! \brief Provides the fixed ciphertext length, if one exists
	//! \returns the fixed ciphertext length if one exists, otherwise 0
	//! \details "Fixed" here means length of ciphertext does not depend on length of plaintext.
	//!   In this case, it usually does depend on the key length.
	virtual size_t FixedCiphertextLength() const {return 0;}

	//! \brief Provides the maximum plaintext length given a fixed ciphertext length
	//! \return maximum plaintext length given the fixed ciphertext length, if one exists,
	//!   otherwise return 0.
	//! \details FixedMaxPlaintextLength(0 returns the maximum plaintext length given the fixed ciphertext
	//!   length, if one exists, otherwise return 0.
	virtual size_t FixedMaxPlaintextLength() const {return 0;}
	
#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	size_t MaxPlainTextLength(size_t cipherTextLength) const {return MaxPlaintextLength(cipherTextLength);}
	size_t CipherTextLength(size_t plainTextLength) const {return CiphertextLength(plainTextLength);}
#endif
};

//! \class PK_Encryptor
//! \brief Interface for public-key encryptors
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_Encryptor : public PK_CryptoSystem, public PublicKeyAlgorithm
{
public:
	//! \brief Exception thrown when trying to encrypt plaintext of invalid length
	class CRYPTOPP_DLL InvalidPlaintextLength : public Exception
	{
	public:
		InvalidPlaintextLength() : Exception(OTHER_ERROR, "PK_Encryptor: invalid plaintext length") {}
	};

	//! \brief Encrypt a byte string
	//! \param rng a RandomNumberGenerator derived class
	//! \param plaintext the plaintext byte buffer
	//! \param plaintextLength the size of the plaintext byte buffer
	//! \param ciphertext a byte buffer to hold the encrypted string
	//! \param parameters a set of NameValuePairs to initialize this object
	//! \pre <tt>CiphertextLength(plaintextLength) != 0</tt> ensures the plaintext isn't too large
	//! \pre <tt>COUNTOF(ciphertext) == CiphertextLength(plaintextLength)</tt> ensures the output
	//!   byte buffer is large enough.
	//! \sa PK_Decryptor
	virtual void Encrypt(RandomNumberGenerator &rng, 
		const byte *plaintext, size_t plaintextLength, 
		byte *ciphertext, const NameValuePairs &parameters = g_nullNameValuePairs) const =0;

	//! \brief Create a new encryption filter
	//! \param rng a RandomNumberGenerator derived class
	//! \param attachment an attached transformation
	//! \param parameters a set of NameValuePairs to initialize this object
	//! \details \p attachment can be \p NULL. The caller is responsible for deleting the returned pointer.
	//!   Encoding parameters should be passed in the "EP" channel.
	virtual BufferedTransformation * CreateEncryptionFilter(RandomNumberGenerator &rng,
		BufferedTransformation *attachment=NULL, const NameValuePairs &parameters = g_nullNameValuePairs) const;
};

//! \class PK_Decryptor
//! \brief Interface for public-key decryptors
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_Decryptor : public PK_CryptoSystem, public PrivateKeyAlgorithm
{
public:
	//! \brief Decrypt a byte string
	//! \param rng a RandomNumberGenerator derived class
	//! \param ciphertext the encrypted byte buffer
	//! \param ciphertextLength the size of the encrypted byte buffer
	//! \param plaintext a byte buffer to hold the decrypted string
	//! \param parameters a set of NameValuePairs to initialize this object
	//! \returns the result of the decryption operation
	//! \pre <tt>COUNTOF(plaintext) == MaxPlaintextLength(ciphertextLength)</tt> ensures the output
	//!   byte buffer is large enough
	//! \details If DecodingResult::isValidCoding is true, then DecodingResult::messageLength
	//!   is valid and holds the the actual length of the plaintext recovered.
	//!   on success. The result is undefined if decryption failed. If DecodingResult::isValidCoding
	//!   is false, then DecodingResult::messageLength is undefined.
	//! \sa PK_Encryptor
	virtual DecodingResult Decrypt(RandomNumberGenerator &rng, 
		const byte *ciphertext, size_t ciphertextLength, 
		byte *plaintext, const NameValuePairs &parameters = g_nullNameValuePairs) const =0;

	//! create a new decryption filter
	/*! \note caller is responsible for deleting the returned pointer
	*/
	virtual BufferedTransformation * CreateDecryptionFilter(RandomNumberGenerator &rng, 
		BufferedTransformation *attachment=NULL, const NameValuePairs &parameters = g_nullNameValuePairs) const;

	//! decrypt a fixed size ciphertext
	DecodingResult FixedLengthDecrypt(RandomNumberGenerator &rng, const byte *ciphertext, byte *plaintext, const NameValuePairs &parameters = g_nullNameValuePairs) const
		{return Decrypt(rng, ciphertext, FixedCiphertextLength(), plaintext, parameters);}

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PK_Decryptor() {}
#endif
};

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
typedef PK_CryptoSystem PK_FixedLengthCryptoSystem;
typedef PK_Encryptor PK_FixedLengthEncryptor;
typedef PK_Decryptor PK_FixedLengthDecryptor;
#endif

//! \class PK_SignatureScheme
//! \brief Interface for public-key signers and verifiers
//! \details This class provides an interface common to signers and verifiers for querying scheme properties
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_SignatureScheme
{
public:
	//! \class InvalidKeyLength
	//! \brief Exception throw when the private or public key has a length that can't be used
	//! \details InvalidKeyLength() may be thrown by any function in this class if the private
	//!   or public key has a length that can't be used
	class CRYPTOPP_DLL InvalidKeyLength : public Exception
	{
	public:
		InvalidKeyLength(const std::string &message) : Exception(OTHER_ERROR, message) {}
	};

	//! \class KeyTooShort
	//! \brief Exception throw when the private or public key is too short to sign or verify
	//! \details KeyTooShort() may be thrown by any function in this class if the private or public
	//!   key is too short to sign or verify anything
	class CRYPTOPP_DLL KeyTooShort : public InvalidKeyLength
	{
	public:
		KeyTooShort() : InvalidKeyLength("PK_Signer: key too short for this signature scheme") {}
	};

	virtual ~PK_SignatureScheme() {}

	//! \brief Provides the signature length if it only depends on the key
	//! \returns the signature length if it only depends on the key, in bytes
	//! \details SignatureLength() returns the signature length if it only depends on the key, otherwise 0.
	virtual size_t SignatureLength() const =0;

	//! \brief Provides the maximum signature length produced given the length of the recoverable message part
	//! \param recoverablePartLength the length of the recoverable message part, in bytes
	//! \returns the maximum signature length produced for a given length of recoverable message part, in bytes
	//! \details MaxSignatureLength() returns the maximum signature length produced given the length of the
	//!   recoverable message part.
	virtual size_t MaxSignatureLength(size_t recoverablePartLength = 0) const
	{CRYPTOPP_UNUSED(recoverablePartLength); return SignatureLength();}

	//! \brief Provides the length of longest message that can be recovered
	//! \returns the length of longest message that can be recovered, in bytes
	//! \details MaxRecoverableLength() returns the length of longest message that can be recovered, or 0 if
	//!   this signature scheme does not support message recovery.
	virtual size_t MaxRecoverableLength() const =0;

	//! \brief Provides the length of longest message that can be recovered from a signature of given length
	//! \param signatureLength the length of the signature, in bytes
	//! \returns the length of longest message that can be recovered from a signature of given length, in bytes
	//! \details MaxRecoverableLengthFromSignatureLength() returns the length of longest message that can be
	//!   recovered from a signature of given length, or 0 if this signature scheme does not support message
	//!   recovery.
	virtual size_t MaxRecoverableLengthFromSignatureLength(size_t signatureLength) const =0;

	//! \brief Determines whether a signature scheme requires a random number generator
	//! \returns true if the signature scheme requires a RandomNumberGenerator() to sign
	//! \details if IsProbabilistic() returns false, then NullRNG() can be passed to functions that take
	//!   RandomNumberGenerator().
	virtual bool IsProbabilistic() const =0;

	//! \brief Determines whether the non-recoverable message part can be signed
	//! \returns true if the non-recoverable message part can be signed
	virtual bool AllowNonrecoverablePart() const =0;

	//! \brief Determines whether the signature must be input before the message
	//! \returns true if the signature must be input before the message during verifcation
	//! \details if SignatureUpfront() returns true, then you must input the signature before the message
	//!   during verification. Otherwise you can input the signature at anytime.
	virtual bool SignatureUpfront() const {return false;}

	//! \brief Determines whether the recoverable part must be input before the non-recoverable part
	//! \returns true if the recoverable part must be input before the non-recoverable part during signing
	//! \details RecoverablePartFirst() determines whether you must input the recoverable part before the
	//!   non-recoverable part during signing
	virtual bool RecoverablePartFirst() const =0;
};

//! \class PK_MessageAccumulator
//! \brief Interface for accumulating messages to be signed or verified
//! \details Only Update() should be called from the PK_MessageAccumulator() class. No other functions
//!   inherited from HashTransformation, like DigestSize() and TruncatedFinal(), should be called.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_MessageAccumulator : public HashTransformation
{
public:
	//! should not be called on PK_MessageAccumulator
	unsigned int DigestSize() const
		{throw NotImplemented("PK_MessageAccumulator: DigestSize() should not be called");}

	//! should not be called on PK_MessageAccumulator
	void TruncatedFinal(byte *digest, size_t digestSize) 
	{
		CRYPTOPP_UNUSED(digest); CRYPTOPP_UNUSED(digestSize);
		throw NotImplemented("PK_MessageAccumulator: TruncatedFinal() should not be called");
	}
};

//! \class PK_Signer
//! \brief Interface for public-key signers
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_Signer : public PK_SignatureScheme, public PrivateKeyAlgorithm
{
public:
	//! \brief Create a new HashTransformation to accumulate the message to be signed
	//! \param rng a RandomNumberGenerator derived class
	//! \returns a pointer to a PK_MessageAccumulator
	//! \details NewSignatureAccumulator() can be used with all signing methods. Sign() will autimatically delete the
	//!   accumulator pointer. The caller is responsible for deletion if a methods is called that takes a reference.
	virtual PK_MessageAccumulator * NewSignatureAccumulator(RandomNumberGenerator &rng) const =0;

	//! \brief Input a recoverable message to an accumulator
	//! \param messageAccumulator a reference to a PK_MessageAccumulator
	//! \param recoverableMessage a pointer to the recoverable message part to be signed
	//! \param recoverableMessageLength the size of the recoverable message part
	virtual void InputRecoverableMessage(PK_MessageAccumulator &messageAccumulator, const byte *recoverableMessage, size_t recoverableMessageLength) const =0;

	//! \brief Sign and delete the messageAccumulator
	//! \param rng a RandomNumberGenerator derived class
	//! \param messageAccumulator a pointer to a PK_MessageAccumulator derived class
	//! \param signature a block of bytes for the signature
	//! \returns actual signature length
	//! \details Sign() deletes the messageAccumulator, even if an exception is thrown.
	//! \pre <tt>size of signature == MaxSignatureLength()</tt>
	virtual size_t Sign(RandomNumberGenerator &rng, PK_MessageAccumulator *messageAccumulator, byte *signature) const;

	//! \brief Sign and restart messageAccumulator
	//! \param rng a RandomNumberGenerator derived class
	//! \param messageAccumulator a pointer to a PK_MessageAccumulator derived class
	//! \param signature a block of bytes for the signature
	//! \param restart flag indicating whether the messageAccumulator should be restarted
	//! \returns actual signature length
	//! \pre <tt>size of signature == MaxSignatureLength()</tt>
	virtual size_t SignAndRestart(RandomNumberGenerator &rng, PK_MessageAccumulator &messageAccumulator, byte *signature, bool restart=true) const =0;

	//! \brief Sign a message
	//! \param rng a RandomNumberGenerator derived class
	//! \param message a pointer to the message
	//! \param messageLen the size of the message to be signed
	//! \param signature a block of bytes for the signature
	//! \returns actual signature length
	//! \pre <tt>size of signature == MaxSignatureLength()</tt>
	virtual size_t SignMessage(RandomNumberGenerator &rng, const byte *message, size_t messageLen, byte *signature) const;

	//! \brief Sign a recoverable message
	//! \param rng a RandomNumberGenerator derived class
	//! \param recoverableMessage a pointer to the recoverable message part to be signed
	//! \param recoverableMessageLength the size of the recoverable message part
	//! \param nonrecoverableMessage a pointer to the non-recoverable message part to be signed
	//! \param nonrecoverableMessageLength the size of the non-recoverable message part
	//! \param signature a block of bytes for the signature
	//! \pre <tt>size of signature == MaxSignatureLength(recoverableMessageLength)</tt>
	//! \returns actual signature length
	virtual size_t SignMessageWithRecovery(RandomNumberGenerator &rng, const byte *recoverableMessage, size_t recoverableMessageLength, 
		const byte *nonrecoverableMessage, size_t nonrecoverableMessageLength, byte *signature) const;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PK_Signer() {}
#endif
};

//! \class PK_Verifier
//! \brief Interface for public-key signature verifiers
//! \details The Recover* functions throw NotImplemented if the signature scheme does not support
//!   message recovery.
//! \details The Verify* functions throw InvalidDataFormat if the scheme does support message
//!   recovery and the signature contains a non-empty recoverable message part. The
//!   Recovery* functions should be used in that case.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE PK_Verifier : public PK_SignatureScheme, public PublicKeyAlgorithm
{
public:
	//! create a new HashTransformation to accumulate the message to be verified
	virtual PK_MessageAccumulator * NewVerificationAccumulator() const =0;

	//! input signature into a message accumulator
	virtual void InputSignature(PK_MessageAccumulator &messageAccumulator, const byte *signature, size_t signatureLength) const =0;

	//! check whether messageAccumulator contains a valid signature and message, and delete messageAccumulator (even in case of exception thrown)
	virtual bool Verify(PK_MessageAccumulator *messageAccumulator) const;

	//! check whether messageAccumulator contains a valid signature and message, and restart messageAccumulator
	virtual bool VerifyAndRestart(PK_MessageAccumulator &messageAccumulator) const =0;

	//! check whether input signature is a valid signature for input message
	virtual bool VerifyMessage(const byte *message, size_t messageLen, 
		const byte *signature, size_t signatureLength) const;

	//! recover a message from its signature
	/*! \pre size of recoveredMessage == MaxRecoverableLengthFromSignatureLength(signatureLength)
	*/
	virtual DecodingResult Recover(byte *recoveredMessage, PK_MessageAccumulator *messageAccumulator) const;

	//! recover a message from its signature
	/*! \pre size of recoveredMessage == MaxRecoverableLengthFromSignatureLength(signatureLength)
	*/
	virtual DecodingResult RecoverAndRestart(byte *recoveredMessage, PK_MessageAccumulator &messageAccumulator) const =0;

	//! recover a message from its signature
	/*! \pre size of recoveredMessage == MaxRecoverableLengthFromSignatureLength(signatureLength)
	*/
	virtual DecodingResult RecoverMessage(byte *recoveredMessage, 
		const byte *nonrecoverableMessage, size_t nonrecoverableMessageLength, 
		const byte *signature, size_t signatureLength) const;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PK_Verifier() {}
#endif
};

//! \class SimpleKeyAgreementDomain
//! \brief Interface for domains of simple key agreement protocols
//! \details A key agreement domain is a set of parameters that must be shared
//!   by two parties in a key agreement protocol, along with the algorithms
//!   for generating key pairs and deriving agreed values.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE SimpleKeyAgreementDomain : public KeyAgreementAlgorithm
{
public:
	//! return length of agreed value produced
	virtual unsigned int AgreedValueLength() const =0;
	//! return length of private keys in this domain
	virtual unsigned int PrivateKeyLength() const =0;
	//! return length of public keys in this domain
	virtual unsigned int PublicKeyLength() const =0;
	//! generate private key
	/*! \pre size of privateKey == PrivateKeyLength() */
	virtual void GeneratePrivateKey(RandomNumberGenerator &rng, byte *privateKey) const =0;
	//! generate public key
	/*!	re size of publicKey == PublicKeyLength() */
	virtual void GeneratePublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const =0;
	//! generate private/public key pair
	/*! \note equivalent to calling GeneratePrivateKey() and then GeneratePublicKey() */
	virtual void GenerateKeyPair(RandomNumberGenerator &rng, byte *privateKey, byte *publicKey) const;
	//! derive agreed value from your private key and couterparty's public key, return false in case of failure
	/*! \note If you have previously validated the public key, use validateOtherPublicKey=false to save time.
		re size of agreedValue == AgreedValueLength()
		\pre length of privateKey == PrivateKeyLength()
		\pre length of otherPublicKey == PublicKeyLength()
	*/
	virtual bool Agree(byte *agreedValue, const byte *privateKey, const byte *otherPublicKey, bool validateOtherPublicKey=true) const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~SimpleKeyAgreementDomain() {}
#endif

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	bool ValidateDomainParameters(RandomNumberGenerator &rng) const
		{return GetCryptoParameters().Validate(rng, 2);}
#endif
};

//! \brief Interface for domains of authenticated key agreement protocols

/*! In an authenticated key agreement protocol, each party has two
	key pairs. The long-lived key pair is called the static key pair,
	and the short-lived key pair is called the ephemeral key pair.
*/
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE AuthenticatedKeyAgreementDomain : public KeyAgreementAlgorithm
{
public:
	//! return length of agreed value produced
	virtual unsigned int AgreedValueLength() const =0;

	//! return length of static private keys in this domain
	virtual unsigned int StaticPrivateKeyLength() const =0;
	//! return length of static public keys in this domain
	virtual unsigned int StaticPublicKeyLength() const =0;
	//! generate static private key
	/*! \pre size of privateKey == PrivateStaticKeyLength() */
	virtual void GenerateStaticPrivateKey(RandomNumberGenerator &rng, byte *privateKey) const =0;
	//! generate static public key
	/*!	re size of publicKey == PublicStaticKeyLength() */
	virtual void GenerateStaticPublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const =0;
	//! generate private/public key pair
	/*! \note equivalent to calling GenerateStaticPrivateKey() and then GenerateStaticPublicKey() */
	virtual void GenerateStaticKeyPair(RandomNumberGenerator &rng, byte *privateKey, byte *publicKey) const;

	//! return length of ephemeral private keys in this domain
	virtual unsigned int EphemeralPrivateKeyLength() const =0;
	//! return length of ephemeral public keys in this domain
	virtual unsigned int EphemeralPublicKeyLength() const =0;
	//! \brief Generate ephemeral private key
	//! \pre size of privateKey == PrivateEphemeralKeyLength()
	virtual void GenerateEphemeralPrivateKey(RandomNumberGenerator &rng, byte *privateKey) const =0;
	//! \brief Generate ephemeral public key
	//! \pre size of publicKey == PublicEphemeralKeyLength()
	virtual void GenerateEphemeralPublicKey(RandomNumberGenerator &rng, const byte *privateKey, byte *publicKey) const =0;
	//! \brief Generate private/public key pair
	/*! \note equivalent to calling GenerateEphemeralPrivateKey() and then GenerateEphemeralPublicKey() */
	virtual void GenerateEphemeralKeyPair(RandomNumberGenerator &rng, byte *privateKey, byte *publicKey) const;

	//! \brief Derive agreed value
	//! \returns true upon success, false in case of failure
	//! \details Agree() derives an agreed value from your private keys and couterparty's public keys
	//! \details The ephemeral public key will always be validated. If you have previously validated the
	//!   static public key, use validateStaticOtherPublicKey=false to save time.
	//! \pre size of agreedValue == AgreedValueLength()
	//! \pre length of staticPrivateKey == StaticPrivateKeyLength()
	//! \pre length of ephemeralPrivateKey == EphemeralPrivateKeyLength()
	//! \pre length of staticOtherPublicKey == StaticPublicKeyLength()
	//! \pre length of ephemeralOtherPublicKey == EphemeralPublicKeyLength()
	virtual bool Agree(byte *agreedValue,
		const byte *staticPrivateKey, const byte *ephemeralPrivateKey,
		const byte *staticOtherPublicKey, const byte *ephemeralOtherPublicKey,
		bool validateStaticOtherPublicKey=true) const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~AuthenticatedKeyAgreementDomain() {}
#endif

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
	bool ValidateDomainParameters(RandomNumberGenerator &rng) const
		{return GetCryptoParameters().Validate(rng, 2);}
#endif
};

// interface for password authenticated key agreement protocols, not implemented yet
#if 0
//! \brief Interface for protocol sessions
/*! The methods should be called in the following order:

	InitializeSession(rng, parameters);	// or call initialize method in derived class
	while (true)
	{
		if (OutgoingMessageAvailable())
		{
			length = GetOutgoingMessageLength();
			GetOutgoingMessage(message);
			; // send outgoing message
		}

		if (LastMessageProcessed())
			break;

		; // receive incoming message
		ProcessIncomingMessage(message);
	}
	; // call methods in derived class to obtain result of protocol session
*/
class ProtocolSession
{
public:
	//! exception thrown when an invalid protocol message is processed
	class ProtocolError : public Exception
	{
	public:
		ProtocolError(ErrorType errorType, const std::string &s) : Exception(errorType, s) {}
	};

	//! exception thrown when a function is called unexpectedly
	/*! for example calling ProcessIncomingMessage() when ProcessedLastMessage() == true */
	class UnexpectedMethodCall : public Exception
	{
	public:
		UnexpectedMethodCall(const std::string &s) : Exception(OTHER_ERROR, s) {}
	};

	ProtocolSession() : m_rng(NULL), m_throwOnProtocolError(true), m_validState(false) {}
	virtual ~ProtocolSession() {}

	virtual void InitializeSession(RandomNumberGenerator &rng, const NameValuePairs &parameters) =0;

	bool GetThrowOnProtocolError() const {return m_throwOnProtocolError;}
	void SetThrowOnProtocolError(bool throwOnProtocolError) {m_throwOnProtocolError = throwOnProtocolError;}

	bool HasValidState() const {return m_validState;}

	virtual bool OutgoingMessageAvailable() const =0;
	virtual unsigned int GetOutgoingMessageLength() const =0;
	virtual void GetOutgoingMessage(byte *message) =0;

	virtual bool LastMessageProcessed() const =0;
	virtual void ProcessIncomingMessage(const byte *message, unsigned int messageLength) =0;

protected:
	void HandleProtocolError(Exception::ErrorType errorType, const std::string &s) const;
	void CheckAndHandleInvalidState() const;
	void SetValidState(bool valid) {m_validState = valid;}

	RandomNumberGenerator *m_rng;

private:
	bool m_throwOnProtocolError, m_validState;
};

class KeyAgreementSession : public ProtocolSession
{
public:
	virtual unsigned int GetAgreedValueLength() const =0;
	virtual void GetAgreedValue(byte *agreedValue) const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~KeyAgreementSession() {}
#endif
};

class PasswordAuthenticatedKeyAgreementSession : public KeyAgreementSession
{
public:
	void InitializePasswordAuthenticatedKeyAgreementSession(RandomNumberGenerator &rng, 
		const byte *myId, unsigned int myIdLength, 
		const byte *counterPartyId, unsigned int counterPartyIdLength, 
		const byte *passwordOrVerifier, unsigned int passwordOrVerifierLength);

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PasswordAuthenticatedKeyAgreementSession() {}
#endif
};

class PasswordAuthenticatedKeyAgreementDomain : public KeyAgreementAlgorithm
{
public:
	//! return whether the domain parameters stored in this object are valid
	virtual bool ValidateDomainParameters(RandomNumberGenerator &rng) const
		{return GetCryptoParameters().Validate(rng, 2);}

	virtual unsigned int GetPasswordVerifierLength(const byte *password, unsigned int passwordLength) const =0;
	virtual void GeneratePasswordVerifier(RandomNumberGenerator &rng, const byte *userId, unsigned int userIdLength, const byte *password, unsigned int passwordLength, byte *verifier) const =0;

	enum RoleFlags {CLIENT=1, SERVER=2, INITIATOR=4, RESPONDER=8};

	virtual bool IsValidRole(unsigned int role) =0;
	virtual PasswordAuthenticatedKeyAgreementSession * CreateProtocolSession(unsigned int role) const =0;

#ifndef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562
	virtual ~PasswordAuthenticatedKeyAgreementDomain() {}
#endif
};
#endif

//! \brief Exception thrown when an ASN1 BER decoing error is encountered
class CRYPTOPP_DLL BERDecodeErr : public InvalidArgument
{
public: 
	BERDecodeErr() : InvalidArgument("BER decode error") {}
	BERDecodeErr(const std::string &s) : InvalidArgument(s) {}
};

//! \brief Interface for encoding and decoding ASN1 objects
//! \details Each class that derives from ASN1Object should provide a serialization format
//!   that controls subobject layout. Most of the time the serialization format is
//!   taken from a standard, like P1363 or an RFC.
class CRYPTOPP_DLL CRYPTOPP_NO_VTABLE ASN1Object
{
public:
	virtual ~ASN1Object() {}
	
	//! \brief Decode this object from a BufferedTransformation
	//! \param bt BufferedTransformation object
	//! \details Uses Basic Encoding Rules (BER)
	virtual void BERDecode(BufferedTransformation &bt) =0;
	
	//! \brief Encode this object into a BufferedTransformation
	//! \param bt BufferedTransformation object
	//! \details Uses Distinguished Encoding Rules (DER)
	virtual void DEREncode(BufferedTransformation &bt) const =0;
	
	//! \brief Encode this object into a BufferedTransformation
	//! \param bt BufferedTransformation object
	//! \details Uses Basic Encoding Rules (BER).
	//! \details This may be useful if DEREncode() would be too inefficient.
	virtual void BEREncode(BufferedTransformation &bt) const {DEREncode(bt);}
};

#ifdef CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY
typedef PK_SignatureScheme PK_SignatureSystem;
typedef SimpleKeyAgreementDomain PK_SimpleKeyAgreementDomain;
typedef AuthenticatedKeyAgreementDomain PK_AuthenticatedKeyAgreementDomain;
#endif

NAMESPACE_END

#if CRYPTOPP_MSC_VERSION
# pragma warning(pop)
#endif

#endif