Provide preset parameters for RFC 9106

GitHub: #8

Allow users to choose from recommended parameters from RFC 9106 and the
OWASP Password Storage Cheat Sheet by providing them as constants on
`Argon2id`.

To allow users to use this as defaults without having to pass them to
every call to `Argon2id::Password.create`, add a new
`Argon2id.set_defaults` (and corresponding `Argon2id.defaults`) method
for setting multiple parameters at once.

README.md

@@ -110,6 +110,35 @@ password.to_s
 #=> "$argon2id$v=19$m=12288,t=3,p=1$uukIsLS6y6etvsgoN20kVg$exMvDX/P9exvEPmnZL2gZClRyMdrnqjqyysLMP/VUWA"
 ```
 
+For convenience, several sets of parameters are available as constants:
+
+1.  The first recommended option from [RFC
+    9106](https://datatracker.ietf.org/doc/rfc9106/):
+
+    ```ruby
+    password = Argon2id::Password.create("opensesame", **Argon2id::RFC_9106_HIGH_MEMORY)
+    password.to_s
+    #=> "$argon2id$v=19$m=2097152,t=1,p=4$6mZF5heTzNrztem0+ICjpg$ftqgeGJ0Hfsqymu1aeb4cXL11pjgbcIuIjYwFJOOUVM"
+    ```
+
+2.  The second recommended option from RFC 9106:
+
+    ```ruby
+    password = Argon2id::Password.create("opensesame", **Argon2id::RFC_9106_LOW_MEMORY)
+    password.to_s
+    #=> "$argon2id$v=19$m=65536,t=3,p=4$RSoUjYKa5Xg8zoPtv/LJgQ$wKGeEUJXaoG4yRCX5SyINyKWO1a78IL6nVToraNwwqY"
+    ```
+
+3.  The second recommended option from the [OWASP Password Storage Cheat
+    Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html#argon2id)
+    (this is the default if no keyword arguments are passed):
+
+    ```ruby
+    password = Argon2id::Password.create("opensesame", **Argon2id::OWASP_2)
+    password.to_s
+    #=> "$argon2id$v=19$m=19456,t=2,p=1$CG+LJTSf0ghYGvPtUYdyqA$cynug5xL6dRN4YOrG4MCzc/3EWkJxwg+D0gZkoyPeH8"
+    ```
+
 If you want to override the parameters for all calls to
 `Argon2id::Password.create`, you can set them on `Argon2id` directly:
 
@@ -121,6 +150,14 @@ Argon2id.salt_len = 16
 Argon2id.output_len = 32
 ```
 
+To set multiple parameters at once or use one of the constants, you can use
+`Argon2id.set_defaults`:
+
+```ruby
+Argon2id.set_defaults(t_cost: 3, m_cost: 12288)
+Argon2id.set_defaults(**Argon2id::RFC_9106_HIGH_MEMORY)
+```
+
 ### Verifying passwords
 
 To verify a password against a hash, use `Argon2id::Password#==`:

lib/argon2id.rb

@@ -5,20 +5,53 @@
 require "argon2id/version"
 
 module Argon2id
+  # OWASP Password Storage Cheat Sheet second recommended parameters.
+  #
+  # See https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html#argon2id
+  OWASP_2 = {
+    t_cost: 2,
+    m_cost: 19_456,
+    parallelism: 1,
+    salt_len: 16,
+    output_len: 32
+  }.freeze
+
+  # RFC 9106 first recommended parameters.
+  #
+  # See 4. Parameter Choice in https://datatracker.ietf.org/doc/rfc9106/
+  RFC_9106_HIGH_MEMORY = {
+    t_cost: 1,
+    parallelism: 4,
+    m_cost: 2_097_152,
+    salt_len: 16,
+    output_len: 32
+  }.freeze
+
+  # RFC 9106 second recommended parameters.
+  #
+  # See 4. Parameter Choice in https://datatracker.ietf.org/doc/rfc9106/
+  RFC_9106_LOW_MEMORY = {
+    t_cost: 3,
+    parallelism: 4,
+    m_cost: 65_536,
+    salt_len: 16,
+    output_len: 32
+  }.freeze
+
   # The default "time cost" of 2 iterations recommended by OWASP.
-  DEFAULT_T_COST = 2
+  DEFAULT_T_COST = OWASP_2[:t_cost]
 
   # The default "memory cost" of 19 mebibytes recommended by OWASP.
-  DEFAULT_M_COST = 19_456
+  DEFAULT_M_COST = OWASP_2[:m_cost]
 
   # The default 1 thread and compute lane recommended by OWASP.
-  DEFAULT_PARALLELISM = 1
+  DEFAULT_PARALLELISM = OWASP_2[:parallelism]
 
   # The default salt length of 16 bytes.
-  DEFAULT_SALT_LEN = 16
+  DEFAULT_SALT_LEN = OWASP_2[:salt_len]
 
   # The default desired hash length of 32 bytes.
-  DEFAULT_OUTPUT_LEN = 32
+  DEFAULT_OUTPUT_LEN = OWASP_2[:output_len]
 
   @t_cost = DEFAULT_T_COST
   @m_cost = DEFAULT_M_COST
@@ -41,5 +74,33 @@ class << self
 
     # The default desired length of the hash in bytes used by Argon2id::Password.create
     attr_accessor :output_len
+
+    # Set default parameters used by Argon2id::Password.create
+    #
+    #   Argon2id.set_defaults(t_cost: 1, m_cost: 47104, parallelism: 1)
+    #   Argon2id.set_defaults(**Argon2id::RFC_9106_HIGH_MEMORY)
+    def set_defaults(t_cost: self.t_cost, m_cost: self.m_cost, parallelism: self.parallelism, salt_len: self.salt_len, output_len: self.output_len)
+      @t_cost = t_cost
+      @m_cost = m_cost
+      @parallelism = parallelism
+      @salt_len = salt_len
+      @output_len = output_len
+
+      defaults
+    end
+
+    # Return all default parameters used by Argon2id::Password.create
+    #
+    #   Argon2id.defaults
+    #   #=> {:t_cost=>2, :m_cost=>19456, :parallelism=>1, :salt_len=>16, :output_len=>32}
+    def defaults
+      {
+        t_cost: t_cost,
+        m_cost: m_cost,
+        parallelism: parallelism,
+        salt_len: salt_len,
+        output_len: output_len
+      }
+    end
   end
 end

test/test_argon2id.rb

@@ -63,4 +63,130 @@ def test_output_len_can_be_overridden
   ensure
     Argon2id.output_len = Argon2id::DEFAULT_OUTPUT_LEN
   end
+
+  def test_owasp_2_uses_t_cost_of_2
+    assert_equal 2, Argon2id::OWASP_2[:t_cost]
+  end
+
+  def test_owasp_2_uses_parallelism_of_1
+    assert_equal 1, Argon2id::OWASP_2[:parallelism]
+  end
+
+  def test_owasp_2_uses_m_cost_of_19_mib
+    assert_equal 19_456, Argon2id::OWASP_2[:m_cost]
+  end
+
+  def test_owasp_2_uses_salt_len_of_128_bits
+    assert_equal 128/8, Argon2id::OWASP_2[:salt_len]
+  end
+
+  def test_owasp_2_uses_output_len_of_256_bits
+    assert_equal 256/8, Argon2id::OWASP_2[:output_len]
+  end
+
+  def test_rfc_9106_high_memory_uses_t_cost_of_1
+    assert_equal 1, Argon2id::RFC_9106_HIGH_MEMORY[:t_cost]
+  end
+
+  def test_rfc_9106_high_memory_uses_parallelism_of_4
+    assert_equal 4, Argon2id::RFC_9106_HIGH_MEMORY[:parallelism]
+  end
+
+  def test_rfc_9106_high_memory_uses_m_cost_of_2_gib
+    assert_equal 2**21, Argon2id::RFC_9106_HIGH_MEMORY[:m_cost]
+  end
+
+  def test_rfc_9106_high_memory_uses_salt_len_of_128_bits
+    assert_equal 128/8, Argon2id::RFC_9106_HIGH_MEMORY[:salt_len]
+  end
+
+  def test_rfc_9106_high_memory_uses_output_len_of_256_bits
+    assert_equal 256/8, Argon2id::RFC_9106_HIGH_MEMORY[:output_len]
+  end
+
+  def test_rfc_9106_low_memory_uses_t_cost_of_3
+    assert_equal 3, Argon2id::RFC_9106_LOW_MEMORY[:t_cost]
+  end
+
+  def test_rfc_9106_low_memory_uses_parallelism_of_4
+    assert_equal 4, Argon2id::RFC_9106_LOW_MEMORY[:parallelism]
+  end
+
+  def test_rfc_9106_low_memory_uses_m_cost_of_64_mib
+    assert_equal 2**16, Argon2id::RFC_9106_LOW_MEMORY[:m_cost]
+  end
+
+  def test_rfc_9106_low_memory_uses_salt_len_of_128_bits
+    assert_equal 128/8, Argon2id::RFC_9106_LOW_MEMORY[:salt_len]
+  end
+
+  def test_rfc_9106_low_memory_uses_output_len_of_256_bits
+    assert_equal 256/8, Argon2id::RFC_9106_LOW_MEMORY[:output_len]
+  end
+
+  def test_set_defaults_sets_t_cost
+    Argon2id.set_defaults(t_cost: 1)
+
+    assert_equal 1, Argon2id.t_cost
+  ensure
+    Argon2id.t_cost = Argon2id::DEFAULT_T_COST
+  end
+
+  def test_set_defaults_does_not_change_missing_parameters
+    Argon2id.m_cost = 47_014
+    Argon2id.set_defaults(t_cost: 1)
+
+    assert_equal 47_014, Argon2id.m_cost
+  ensure
+    Argon2id.t_cost = Argon2id::DEFAULT_T_COST
+    Argon2id.m_cost = Argon2id::DEFAULT_M_COST
+  end
+
+  def test_set_defaults_sets_m_cost
+    Argon2id.set_defaults(m_cost: 47_104)
+
+    assert_equal 47_104, Argon2id.m_cost
+  ensure
+    Argon2id.m_cost = Argon2id::DEFAULT_M_COST
+  end
+
+  def test_set_defaults_sets_parallelism
+    Argon2id.set_defaults(parallelism: 4)
+
+    assert_equal 4, Argon2id.parallelism
+  ensure
+    Argon2id.parallelism = Argon2id::DEFAULT_PARALLELISM
+  end
+
+  def test_set_defaults_sets_salt_len
+    Argon2id.set_defaults(salt_len: 32)
+
+    assert_equal 32, Argon2id.salt_len
+  ensure
+    Argon2id.salt_len = Argon2id::DEFAULT_SALT_LEN
+  end
+
+  def test_set_defaults_sets_output_len
+    Argon2id.set_defaults(output_len: 32)
+
+    assert_equal 32, Argon2id.output_len
+  ensure
+    Argon2id.output_len = Argon2id::DEFAULT_OUTPUT_LEN
+  end
+
+  def test_set_defaults_returns_all_defaults
+    assert_equal(
+      { t_cost: 2, m_cost: 19_456, parallelism: 1, salt_len: 16, output_len: 16 },
+      Argon2id.set_defaults(output_len: 16)
+    )
+  ensure
+    Argon2id.output_len = Argon2id::DEFAULT_OUTPUT_LEN
+  end
+
+  def test_defaults_returns_all_parameters
+    assert_equal(
+      { t_cost: 2, m_cost: 19_456, parallelism: 1, salt_len: 16, output_len: 32 },
+      Argon2id.defaults
+    )
+  end
 end