Merge pull request #5 from sic2/master

Added tests for invalid Base16 input + made Base enum immutable

Author: ianopolous

src/main/java/io/ipfs/multibase/Base16.java

@@ -1,19 +1,20 @@
 package io.ipfs.multibase;
 
 public class Base16 {
-    public static byte[] decode(String hex)
-    {
+
+    public static byte[] decode(String hex) {
         byte[] res = new byte[hex.length()/2];
-        for (int i=0; i < res.length; i++)
-            res[i] = (byte) Integer.parseInt(hex.substring(2*i, 2*i+2), 16);
+        for (int i=0; i < res.length; i++) {
+            res[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16);
+        }
         return res;
     }
 
-    public static String encode(byte[] data)
-    {
+    public static String encode(byte[] data) {
         StringBuilder s = new StringBuilder();
-        for (byte b : data)
+        for (byte b : data) {
             s.append(String.format("%02x", b & 0xFF));
+        }
         return s.toString();
     }
 }

src/main/java/io/ipfs/multibase/Base32.java

@@ -0,0 +1,20 @@
+package io.ipfs.multibase;
+
+import java.math.BigInteger;
+
+/**
+ * Based on RFC 4648
+ * No padding
+ */
+public class Base32 {
+    private static final String ALPHABET = "abcdefghijklmnopqrstuvwxyz234567";
+    private static final BigInteger BASE = BigInteger.valueOf(32);
+
+    public static String encode(final byte[] input) {
+        return BaseN.encode(ALPHABET, BASE, input);
+    }
+
+    public static byte[] decode(final String input) {
+        return BaseN.decode(ALPHABET, BASE, input);
+    }
+}

src/main/java/io/ipfs/multibase/Base58.java

@@ -36,54 +36,11 @@ public class Base58 {
     private static final String ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
     private static final BigInteger BASE = BigInteger.valueOf(58);
 
-    public static String encode(byte[] input) {
-        // TODO: This could be a lot more efficient.
-        BigInteger bi = new BigInteger(1, input);
-        StringBuffer s = new StringBuffer();
-        while (bi.compareTo(BASE) >= 0) {
-            BigInteger mod = bi.mod(BASE);
-            s.insert(0, ALPHABET.charAt(mod.intValue()));
-            bi = bi.subtract(mod).divide(BASE);
-        }
-        s.insert(0, ALPHABET.charAt(bi.intValue()));
-        // Convert leading zeros too.
-        for (byte anInput : input) {
-            if (anInput == 0)
-                s.insert(0, ALPHABET.charAt(0));
-            else
-                break;
-        }
-        return s.toString();
+    public static String encode(final byte[] input) {
+        return BaseN.encode(ALPHABET, BASE, input);
     }
 
-    public static byte[] decode(String input) {
-        byte[] bytes = decodeToBigInteger(input).toByteArray();
-        // We may have got one more byte than we wanted, if the high bit of the next-to-last byte was not zero. This
-        // is because BigIntegers are represented with twos-compliment notation, thus if the high bit of the last
-        // byte happens to be 1 another 8 zero bits will be added to ensure the number parses as positive. Detect
-        // that case here and chop it off.
-        boolean stripSignByte = bytes.length > 1 && bytes[0] == 0 && bytes[1] < 0;
-        // Count the leading zeros, if any.
-        int leadingZeros = 0;
-        for (int i = 0; input.charAt(i) == ALPHABET.charAt(0); i++) {
-            leadingZeros++;
-        }
-        // Now cut/pad correctly. Java 6 has a convenience for this, but Android can't use it.
-        byte[] tmp = new byte[bytes.length - (stripSignByte ? 1 : 0) + leadingZeros];
-        System.arraycopy(bytes, stripSignByte ? 1 : 0, tmp, leadingZeros, tmp.length - leadingZeros);
-        return tmp;
-    }
-
-    public static BigInteger decodeToBigInteger(String input) {
-        BigInteger bi = BigInteger.valueOf(0);
-        // Work backwards through the string.
-        for (int i = input.length() - 1; i >= 0; i--) {
-            int alphaIndex = ALPHABET.indexOf(input.charAt(i));
-            if (alphaIndex == -1) {
-                throw new IllegalStateException("Illegal character " + input.charAt(i) + " at " + i);
-            }
-            bi = bi.add(BigInteger.valueOf(alphaIndex).multiply(BASE.pow(input.length() - 1 - i)));
-        }
-        return bi;
+    public static byte[] decode(final String input) {
+        return BaseN.decode(ALPHABET, BASE, input);
     }
 }

src/main/java/io/ipfs/multibase/BaseN.java

@@ -0,0 +1,57 @@
+package io.ipfs.multibase;
+
+import java.math.BigInteger;
+
+public class BaseN {
+
+     static String encode(final String alphabet, final BigInteger base, final byte[] input) {
+        // TODO: This could be a lot more efficient.
+        BigInteger bi = new BigInteger(1, input);
+        StringBuffer s = new StringBuffer();
+        while (bi.compareTo(base) >= 0) {
+            BigInteger mod = bi.mod(base);
+            s.insert(0, alphabet.charAt(mod.intValue()));
+            bi = bi.subtract(mod).divide(base);
+        }
+        s.insert(0, alphabet.charAt(bi.intValue()));
+        // Convert leading zeros too.
+        for (byte anInput : input) {
+            if (anInput == 0)
+                s.insert(0, alphabet.charAt(0));
+            else
+                break;
+        }
+        return s.toString();
+    }
+
+    static byte[] decode(final String alphabet, final BigInteger base, final String input) {
+        byte[] bytes = decodeToBigInteger(alphabet, base, input).toByteArray();
+        // We may have got one more byte than we wanted, if the high bit of the next-to-last byte was not zero. This
+        // is because BigIntegers are represented with twos-compliment notation, thus if the high bit of the last
+        // byte happens to be 1 another 8 zero bits will be added to ensure the number parses as positive. Detect
+        // that case here and chop it off.
+        boolean stripSignByte = bytes.length > 1 && bytes[0] == 0 && bytes[1] < 0;
+        // Count the leading zeros, if any.
+        int leadingZeros = 0;
+        for (int i = 0; input.charAt(i) == alphabet.charAt(0); i++) {
+            leadingZeros++;
+        }
+        // Now cut/pad correctly. Java 6 has a convenience for this, but Android can't use it.
+        byte[] tmp = new byte[bytes.length - (stripSignByte ? 1 : 0) + leadingZeros];
+        System.arraycopy(bytes, stripSignByte ? 1 : 0, tmp, leadingZeros, tmp.length - leadingZeros);
+        return tmp;
+    }
+
+    private static BigInteger decodeToBigInteger(final String alphabet, final BigInteger base, final String input) {
+        BigInteger bi = BigInteger.valueOf(0);
+        // Work backwards through the string.
+        for (int i = input.length() - 1; i >= 0; i--) {
+            int alphaIndex = alphabet.indexOf(input.charAt(i));
+            if (alphaIndex == -1) {
+                throw new IllegalStateException("Illegal character " + input.charAt(i) + " at " + i);
+            }
+            bi = bi.add(BigInteger.valueOf(alphaIndex).multiply(base.pow(input.length() - 1 - i)));
+        }
+        return bi;
+    }
+}

src/main/java/io/ipfs/multibase/Multibase.java

@@ -1,19 +1,22 @@
 package io.ipfs.multibase;
 
-import java.util.*;
+import java.util.Map;
+import java.util.TreeMap;
 
 public class Multibase {
 
     public enum Base {
-        Base1('1'),
-        Base2('0'),
-        Base8('7'),
-        Base10('9'),
-        Base16('f'),
-        Base58Flickr('Z'),
-        Base58BTC('z');
+        // encoding(code)
+        Base1('1'), // unary tends to be 11111
+        Base2('0'), // binary has 1 and 0
+        Base8('7'), // highest char in octal
+        Base10('9'), // highest char in decimal
+        Base16('f'), // highest char in hex
+        Base32('b'), // rfc4648 no padding
+        Base58Flickr('Z'), // highest char
+        Base58BTC('z'); // highest char
 
-        public char prefix;
+        private final char prefix;
 
         Base(char prefix) {
             this.prefix = prefix;
@@ -38,6 +41,8 @@ public static String encode(Base b, byte[] data) {
                 return b.prefix + Base58.encode(data);
             case Base16:
                 return b.prefix + Base16.encode(data);
+            case Base32:
+                return b.prefix + Base32.encode(data);
             default:
                 throw new IllegalStateException("Unsupported base encoding: " + b.name());
         }
@@ -55,6 +60,8 @@ public static byte[] decode(String data) {
                 return Base58.decode(rest);
             case Base16:
                 return Base16.decode(rest);
+            case Base32:
+                return Base32.decode(rest);
             default:
                 throw new IllegalStateException("Unsupported base encoding: " + b.name());
         }

src/test/java/io/ipfs/multibase/MultibaseTest.java

@@ -1,8 +1,12 @@
 package io.ipfs.multibase;
 
-import org.junit.*;
+import org.junit.Test;
 
-import java.util.*;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotEquals;
 
 public class MultibaseTest {
 
@@ -13,20 +17,47 @@ public void base58Test() {
         for (String example: examples) {
             byte[] output = Multibase.decode(example);
             String encoded = Multibase.encode(Multibase.Base.Base58BTC, output);
-            if (!encoded.equals(encoded))
-                throw new IllegalStateException("Incorrect base58! " + example + " => " + encoded);
+            assertEquals(example, encoded);
         }
     }
 
     @Test
     public void base16Test() {
         List<String> examples = Arrays.asList("f234abed8debede",
-                "f87ad873defc2b288a");
+                "f87ad873defc2b288",
+                "f",
+                "f01",
+                "f0123456789abcdef");
         for (String example: examples) {
             byte[] output = Multibase.decode(example);
             String encoded = Multibase.encode(Multibase.Base.Base16, output);
-            if (!encoded.equals(encoded))
-                throw new IllegalStateException("Incorrect base16! " + example + " => " + encoded);
+            assertEquals(example, encoded);
+        }
+    }
+
+    @Test
+    public void base32Test() {
+        List<String> examples = Arrays.asList("bnbswy3dpeb3w64tmmq");
+        for (String example: examples) {
+            byte[] output = Multibase.decode(example);
+            String encoded = Multibase.encode(Multibase.Base.Base32, output);
+            assertEquals(example, encoded);
         }
     }
+
+    @Test
+    public void invalidBase16Test() {
+        String example = "f012"; // hex string of odd length
+        byte[] output = Multibase.decode(example);
+        String encoded = Multibase.encode(Multibase.Base.Base16, output);
+        assertNotEquals(example, encoded);
+
+    }
+
+    @Test (expected = NumberFormatException.class)
+    public void invalidWithExceptionBase16Test() {
+        String example = "f0g"; // g char is not allowed in hex
+        Multibase.decode(example);
+    }
+
 }