Kdf: Split initialize to [copy_key_from, move_key_from, random]. Deprecate old initialize methods.

benchmarks/rand.cr

@@ -3,34 +3,33 @@ require "random/pcg32"
 require "random/isaac"
 require "../src/sodium/cipher/chalsa"
 
-pcgrand = Random::PCG32.new 0
-isaacrand = Random::ISAAC.new Bytes.new(32)
+randoms = {
+  "PCG"    => Random::PCG32.new(0),
+  "ISAAC"  => Random::ISAAC.new(Bytes.new(32)),
+  "Secure" => Random::Secure,
+}
 
 ciphers = {{ Sodium::Cipher::Chalsa.subclasses }}.map do |klass|
-  cipher = klass.new.tap do |c|
-    c.key = Bytes.new c.key_size
-    c.nonce = Bytes.new c.nonce_size
-  end
+  key = Bytes.new klass.key_size
+  nonce = Bytes.new klass.nonce_size
+  cipher = klass.new key, nonce
 
   # {short_name, cipher}
   {klass.to_s.split("::").last, cipher}
 end.to_a
-# p ciphers
 
 buf = Bytes.new 1024
 
 Benchmark.ips warmup: 0.5 do |bm|
-  bm.report "PCG32" do
-    pcgrand.random_bytes buf
-  end
-
-  bm.report "ISAAC" do
-    isaacrand.random_bytes buf
-  end
-
-  ciphers.each do |name, cipher|
+  randoms.each do |name, random|
     bm.report "#{name}" do
-      cipher.random_bytes buf
+      random.random_bytes buf
+    end
+  end
+
+  ciphers.each do |name, random|
+    bm.report "#{name}" do
+      random.random_bytes buf
     end
   end
 end

benchmarks/rand.txt

@@ -1,7 +1,8 @@
-       PCG32 606.78k (  1.65µs) (± 1.07%)  0.0B/op   4.19× slower
-       ISAAC 373.63k (  2.68µs) (± 1.95%)  0.0B/op   6.80× slower
-    XSalsa20   1.84M (544.61ns) (± 1.17%)  0.0B/op   1.38× slower
-     Salsa20   2.37M (421.53ns) (± 1.24%)  0.0B/op   1.07× slower
-   XChaCha20   1.88M (530.86ns) (± 1.46%)  0.0B/op   1.35× slower
-ChaCha20Ietf   2.54M (393.65ns) (± 1.22%)  0.0B/op        fastest
-    ChaCha20   2.51M (398.58ns) (± 1.73%)  0.0B/op   1.01× slower
+         PCG   1.29M (776.49ns) (± 1.13%)  0.0B/op   1.07× slower
+       ISAAC 530.69k (  1.88µs) (± 0.98%)  0.0B/op   2.60× slower
+      Secure 318.19k (  3.14µs) (± 2.30%)  0.0B/op   4.33× slower
+    XSalsa20   1.04M (960.42ns) (± 1.34%)  0.0B/op   1.32× slower
+     Salsa20   1.16M (862.14ns) (± 1.29%)  0.0B/op   1.19× slower
+   XChaCha20   1.22M (818.52ns) (± 1.86%)  0.0B/op   1.13× slower
+ChaCha20Ietf   1.38M (726.43ns) (± 1.28%)  0.0B/op   1.00× slower
+    ChaCha20   1.38M (725.47ns) (± 1.33%)  0.0B/op        fastest

examples/constants.cr

@@ -17,6 +17,14 @@ puts ""
 {% end %}
 puts ""
 
+{% for sk in [Sodium::CryptoBox::SecretKey, Sodium::Sign::SecretKey] %}
+  sk = {{sk.id}}.new
+  pk = sk.public_key
+#  puts "#{sk.class} bytesize #{sk.to_slice.bytesize}"
+  puts "#{pk.class} bytesize #{pk.to_slice.bytesize}"
+{% end %}
+puts ""
+
 {% for name in %w(KEY_SIZE NONCE_SIZE MAC_SIZE) %}
   puts "Sodium::SecretBox::{{ name.id }} #{Sodium::SecretBox::{{ name.id }}}"
 {% end %}
@@ -47,9 +55,8 @@ puts ""
 {% end %}
 puts ""
 
-{% for sk in [Sodium::CryptoBox::SecretKey, Sodium::Sign::SecretKey] %}
-  sk = {{sk.id}}.new
-  pk = sk.public_key
-  puts "#{sk.class} bytesize #{sk.to_slice.bytesize}"
-  puts "#{pk.class} bytesize #{pk.to_slice.bytesize}"
+{% for name in %w(XChaCha20 ChaCha20Ietf ChaCha20 XSalsa20 Salsa20) %}
+  c = Sodium::Cipher::{{name.id}}.random
+#  puts "#{c.class} key_size #{c.key_size}"
+  puts "#{c.class} nonce_size #{c.nonce_size}"
 {% end %}

spec/sodium/cipher/chalsa_spec.cr

@@ -19,6 +19,13 @@ require "../../../src/sodium/cipher/chalsa"
       cipher2.final.should eq Bytes.new(0)
     end
 
+    it "Random" do
+      cipher = Sodium::Cipher::{{ name.id }}.random
+      cipher.random_bytes(8).should_not eq(cipher.random_bytes(8))
+      r = 3.times.map { cipher.rand(65536) }.sum
+      r.should_not eq(0)
+    end
+
     it "dups" do
       cipher1 = Sodium::Cipher::{{ name.id }}.new Bytes.new(Sodium::Cipher::{{ name.id }}::KEY_SIZE)
       cipher2 = cipher1.dup

spec/sodium/kdf_spec.cr

@@ -5,11 +5,11 @@ CONTEXT = "8_bytess"
 
 describe Sodium::Kdf do
   it "generates master key" do
-    kdf1 = Sodium::Kdf.new
+    kdf1 = Sodium::Kdf.random
 
     # verify loading saved key
     kdf2 = kdf1.key.readonly do |kslice|
-      Sodium::Kdf.new kslice.dup
+      Sodium::Kdf.copy_key_from kslice.dup
     end
 
     kdf1.key.should eq kdf2.key
@@ -21,7 +21,7 @@ describe Sodium::Kdf do
   end
 
   it "generates different keys" do
-    kdf1 = Sodium::Kdf.new
+    kdf1 = Sodium::Kdf.random
     subkey1 = kdf1.derive CONTEXT, 0, 16
     subkey2 = kdf1.derive CONTEXT, 1, 16
     subkey1.should_not eq subkey2

spec/sodium/sign/secret_key_spec.cr

@@ -98,6 +98,9 @@ describe Sodium::Sign::SecretKey do
     end
   end
 
+  pending "combined test vectors" do
+  end
+
   it "RbNaCl detached test vectors" do
     detached_test_vectors.each do |vec|
       seckey, plaintext, signature = sign_from_vec vec

src/sodium/cipher/chalsa.cr

@@ -6,15 +6,17 @@ module Sodium::Cipher
   #
   # What? They're both dance?
   abstract class Chalsa
+    include Random
+
     getter key : Crypto::Secret
     getter! nonce : Bytes?
 
     # Advanced usage.  Don't touch.
-    property offset = 0
+    property offset = 0_u64
 
     def initialize(key : Crypto::Secret | Bytes, nonce = nil)
       raise ArgumentError.new("key must be #{key_size} bytes, got #{key.bytesize}") if key.bytesize != key_size
-      @key = key.is_a?(Crypto::Secret) ? key : Sodium::SecureBuffer.new(key)
+      @key = key.is_a?(Crypto::Secret) ? key : Sodium::SecureBuffer.copy_from(key)
       self.nonce = nonce if nonce
     end
 
@@ -42,7 +44,7 @@ module Sodium::Cipher
     end
 
     def random_nonce
-      self.nonce = Random::Secure.random_bytes nonce_size
+      self.nonce = ::Random::Secure.random_bytes nonce_size
     end
 
     # Xor's src with the cipher output and returns a new Slice
@@ -60,17 +62,14 @@ module Sodium::Cipher
 
     # Use as a CSPRNG.
     def random_bytes(bytes : Bytes) : Bytes
-      # TODO: Switch to memset
-      Sodium.memzero bytes
       update bytes, bytes
       bytes
     end
 
-    # Use as a CSPRNG.
-    def random_bytes(size : Int) : Bytes
-      bytes = Bytes.new size
-      update bytes, bytes
-      bytes
+    def next_u : UInt8
+      buf = uninitialized UInt8[1]
+      random_bytes buf.to_slice
+      buf.unsafe_as(UInt8)
     end
 
     # Always returns false. Sadness...
@@ -87,26 +86,35 @@ module Sodium::Cipher
     end
   end
 
-  {% for key, valtup in {"XSalsa20" => {"xsalsa20", false}, "Salsa20" => {"salsa20", false}, "XChaCha20" => {"xchacha20", false}, "ChaCha20Ietf" => {"chacha20_ietf", true}, "ChaCha20" => {"chacha20", false}} %}
-    {% val = valtup[0] %}
-    {% ietf = valtup[1] %}
+  {% for key, val in {"XSalsa20" => "xsalsa20", "Salsa20" => "salsa20", "XChaCha20" => "xchacha20", "ChaCha20Ietf" => "chacha20_ietf", "ChaCha20" => "chacha20"} %}
     # These classes can be used to generate pseudo-random data from a key,
     # or as building blocks for implementing custom constructions, but they
-    # are not alternatives to secretbox.
+    # are not alternatives to `SecretBox`.
     #
     # See [https://libsodium.gitbook.io/doc/advanced/stream_ciphers](https://libsodium.gitbook.io/doc/advanced/stream_ciphers) for further information.
     #
-    # This class mimicks the OpenSSL::Cipher interface with minor differences.
+    # This class mimicks the `OpenSSL::Cipher` interface with minor differences.
+    #
+    # Also provides a `::Random` interface.
+    # * Lacks forward secrecy.
+    # * ~3x faster than `::Random::Secure`
+    #
+    # Use with caution.  When in doubt use `::Random::Secure`
+    #
+    # Possibly safe uses:
+    # * Test data
+    # * Overwriting storage with random data
+    # * Single player video games (maybe)
     #
     # See `spec/sodium/cipher/chalsa_spec.cr` for examples on how to use this class.
     #
     # WARNING: Not validated against test vectors.  You should probably write some before using this class.
     class {{ key.id }} < Chalsa
-      KEY_SIZE = LibSodium.crypto_stream_chacha20_{{ ietf ? "ietf_".id : "".id }}keybytes.to_i32
-      NONCE_SIZE = LibSodium.crypto_stream_chacha20_{{ ietf ? "ietf_".id : "".id }}noncebytes.to_i32
+      KEY_SIZE = LibSodium.crypto_stream_{{ val.id }}_keybytes.to_i32
+      NONCE_SIZE = LibSodium.crypto_stream_{{ val.id }}_noncebytes.to_i32
 
       def self.random
-        new key: Sodium::SecureBuffer.random(KEY_SIZE), nonce: Random::Secure.random_bytes(NONCE_SIZE)
+        new key: Sodium::SecureBuffer.random(KEY_SIZE), nonce: ::Random::Secure.random_bytes(NONCE_SIZE)
       end
 
       # Xor's src with the cipher output and places in dst.
@@ -128,6 +136,14 @@ module Sodium::Cipher
         end
       end
 
+      def self.key_size : Int32
+        KEY_SIZE
+      end
+
+      def self.nonce_size : Int32
+        NONCE_SIZE
+      end
+
       def key_size : Int32
         KEY_SIZE
       end

src/sodium/crypto_box/secret_key.cr

@@ -42,9 +42,6 @@ class Sodium::CryptoBox
     getter key : Crypto::Secret
     getter public_key : PublicKey
 
-    # Returns key
-    delegate_to_slice to: @key
-
     @seed : Crypto::Secret?
 
     # Generate a new random secret/public key pair.
@@ -163,9 +160,12 @@ class Sodium::CryptoBox
     # For authenticated messages use `secret_key.box(recipient_public_key).decrypt`.
     #
     # Optionally supply a destination buffer.
-    def decrypt_string(src, dst : Bytes? = nil) : String
-      msg = decrypt src.to_slice, dst
-      String.new msg
+    def decrypt_string(src) : String
+      dsize = src.bytesize - SEAL_SIZE
+      String.new(dsize) do |dst|
+        decrypt src.to_slice, dst.to_slice(dsize)
+        {dsize, dsize}
+      end
     end
 
     # :nodoc:

src/sodium/kdf.cr

@@ -7,7 +7,8 @@ module Sodium
   #
   # Usage:
   # ```
-  # kdf = KDF.new
+  # kdf = KDF.random
+  # kdf = KDF.move_key_from bytes
   # subkey_id = 0
   # output_size = 16
   # subkey = kdf.derive "8bytectx", subkey_id, output_size
@@ -18,7 +19,7 @@ module Sodium
   #
   # It's recommended to use a #wipe block to erase the master key when no longer needed
   # ```
-  # kdf = Kdf.new
+  # kdf = Kdf.random
   # ...
   # kdf.wipe do
   #  ### Warning: abnormal exit may not wipe
@@ -41,16 +42,29 @@ module Sodium
 
     getter key : Crypto::Secret
 
+    def self.random
+      new(SecureBuffer.random(KEY_SIZE))
+    end
+
     # Use an existing KDF key.
     #
     # * Copies key to a new SecureBuffer
-    # * Optionally erases bytes after copying if erase is set
-    def initialize(bytes : Bytes, erase = false)
-      if bytes.bytesize != KEY_SIZE
-        raise ArgumentError.new("bytes must be #{KEY_SIZE}, got #{bytes.bytesize}")
+    def self.copy_key_from(bytes : Bytes)
+      new(SecureBuffer.copy_from(bytes))
     end
 
-      @key = SecureBuffer.new(bytes, erase).noaccess
+    # Use an existing KDF key.
+    #
+    # * Copies key to a new SecureBuffer
+    # * Erases bytes after copying
+    def self.move_key_from(bytes : Bytes)
+      new(SecureBuffer.move_from(bytes))
+    end
+
+    @[Deprecated("use .copy_key_from or .move_key_from")]
+    def initialize(bytes : Bytes, erase = false)
+      @key = SecureBuffer.new(1)
+      raise NotImplementedError.new("use .copy_key_from or .move_key_from")
     end
 
     # Use an existing KDF Crypto::Secret key.
@@ -61,9 +75,7 @@ module Sodium
       @key.noaccess
     end
 
-    # Generate a new random KDF key.
-    #
-    # Make sure to save kdf.to_slice before kdf goes out of scope.
+    @[Deprecated("use .random")]
     def initialize
       @key = SecureBuffer.random(KEY_SIZE).noaccess
     end

src/sodium/key.cr

@@ -4,7 +4,5 @@ require "./wipe"
 module Sodium
   abstract class Key
     include Sodium::Wipe
-
-    abstract def to_slice : Bytes
   end
 end

src/sodium/secure_buffer.cr

@@ -7,19 +7,20 @@ module Sodium
   #
   # #initialize returns readonly or readwrite for thread safety
   # When state changes are required (such as using #noaccess) and the buffer is accessed from multiple threads wrap each #readonly/#readwrite block in a lock.
-  class SecureBuffer
+  class SecureBuffer < Crypto::Secret
     include Crypto::Secret::Stateful
 
-    getter bytesize : Int32
+    getter buffer_bytesize : Int32
 
-    def initialize(@bytesize : Int32)
-      @ptr = LibSodium.sodium_malloc @bytesize
-      raise Error::OutOfMemory.new if @ptr.null?
+    def initialize(@buffer_bytesize : Int32)
+      @ptr = LibSodium.sodium_malloc @buffer_bytesize
+      raise Error::OutOfMemory.new("allocating #{@buffer_bytesize}") if @ptr.null?
     end
 
     # Copies bytes to a **readonly** SecureBuffer.
     # Optionally erases bytes after copying if erase is set
     # Returns a **readonly** SecureBuffer.
+    @[Deprecated("Use .copy_from or .move_from")]
     def initialize(bytes : Bytes, erase = false)
       initialize bytes.bytesize
       readwrite do |slice|
@@ -32,7 +33,7 @@ module Sodium
     # :nodoc:
     # For .dup
     def initialize(sbuf : Crypto::Secret)
-      initialize sbuf.bytesize
+      initialize sbuf.buffer_bytesize
 
       # Maybe not thread safe
       sbuf.readonly do |sslice|
@@ -56,18 +57,12 @@ module Sodium
     #
     @[Deprecated("Use the Slice provided within a `readonly` or `readwrite` block")]
     def to_slice : Bytes
-      case @state
-      when State::Noaccess, State::Wiped
-        readonly
-      else
-        # Ok
-      end
-      Slice(UInt8).new @ptr, @bytesize
+      raise NotImplementedError.new
     end
 
     protected def to_slice(& : Bytes -> Nil)
       ro = @state < State::Readonly
-      yield Bytes.new(@ptr, @bytesize, read_only: ro)
+      yield Bytes.new(@ptr, @buffer_bytesize, read_only: ro)
     end
 
     # :nodoc: