Breaking API changes:

SignSecretKey rename to Sign::SecretKey
  SignPublicKey rename to Sign::PublicKey
  SignKeyPair removed.  Use Sign::SecretKey instead.

  Cox.sign_detached moved to Sign::SecretKey#sign_detached
  Cox.verify_detached moved to Sign::PublicKey#verify_detached

  verify_detached raises on failure instead of using a return value.

  More validation of data sizes.

README.md

@@ -9,7 +9,7 @@ Updated Crystal bindings for the [libsodium API](https://libsodium.gitbook.io/do
 - Public-Key Cryptography
   - [x] Crypto Box Easy
   - [ ] Sealed Box
-  - [x] Combined Signatures
+  - [ ] Combined Signatures
   - [x] Detached Signatures
 - [Secret-Key Cryptography](https://libsodium.gitbook.io/doc/secret-key_cryptography)
   - Secret Box
@@ -89,13 +89,17 @@ String.new(decrypted) # => "Hello World!"
 ```crystal
 message = "Hello World!"
 
-signing_pair = Cox::SignKeyPair.new
+secret_key = Cox::Sign::SecretKey.new
 
 # Sign the message
-signature = Cox.sign_detached(message, signing_pair.secret)
+signature = secret_key.sign_detached message
 
-# And verify
+# Send secret_key.public_key to the recipient
-Cox.verify_detached(signature, message, signing_pair.public) # => true
+
+public_key = Cox::Sign::PublicKey.new key_bytes
+
+# raises Cox::Error::VerificationFailed on failure.
+public_key.verify_detached message, signature
 ```
 
 ### Secret Key Encryption

spec/cox/secret_key_spec.cr

@@ -9,7 +9,7 @@ describe Cox::SecretKey do
     decrypted = key.decrypt_easy encrypted, nonce
     message.should eq String.new(decrypted)
 
-    expect_raises(Cox::DecryptionFailed) do
+    expect_raises(Cox::Error::DecryptionFailed) do
       key.decrypt_easy "badmsgbadmsgbadmsgbadmsgbadmsg".to_slice, nonce
     end
   end

spec/cox/sign/secret_key.cr

@@ -0,0 +1,22 @@
+require "../../spec_helper"
+require "../../../src/cox/sign/secret_key"
+
+describe Cox::Sign::SecretKey do
+  it "signs and verifies" do
+    message = "foo"
+    skey = Cox::Sign::SecretKey.new
+    sig = skey.sign_detached message
+
+    skey.public_key.verify_detached message, sig
+  end
+
+  it "signs and fails" do
+    message = "foo"
+    skey = Cox::Sign::SecretKey.new
+    sig = skey.sign_detached message
+
+    expect_raises Cox::Error::VerificationFailed do
+      skey.public_key.verify_detached "bar", sig
+    end
+  end
+end

spec/cox_spec.cr

@@ -22,18 +22,4 @@ describe Cox do
 
     String.new(decrypted).should eq(data)
   end
-
-  it "works for signing" do
-    message = "test"
-
-    signing_pair = Cox::SignKeyPair.new
-
-    # Create signature using the secret key
-    signature = Cox.sign_detached(message, signing_pair.secret)
-
-    # Verify the signature on the message
-    verified = Cox.verify_detached(signature, message, signing_pair.public)
-
-    verified.should eq(true)
-  end
 end

src/cox.cr

@@ -2,12 +2,11 @@ require "random/secure"
 
 module Cox
   class Error < ::Exception
-  end
+    class VerificationFailed < Error
+    end
 
-  class VerificationFailed < Error
+    class DecryptionFailed < Error
-  end
+    end
-
-  class DecryptionFailed < Error
   end
 end
 
@@ -34,30 +33,10 @@ module Cox
     data_size = data_buffer.bytesize
     output_buffer = Bytes.new(data_buffer.bytesize - LibSodium::MAC_SIZE)
     if LibSodium.crypto_box_open_easy(output_buffer.to_slice, data_buffer.to_slice, data_size, nonce.to_slice, sender_public_key.to_slice, recipient_secret_key.to_slice) != 0
-      raise DecryptionFailed.new("crypto_box_open_easy")
+      raise Error::DecryptionFailed.new("crypto_box_open_easy")
     end
     output_buffer
   end
-
-  def self.sign_detached(message, secret_key : SignSecretKey)
-    message_buffer = message.to_slice
-    message_buffer_size = message_buffer.bytesize
-    signature_output_buffer = Bytes.new(LibSodium::SIGNATURE_SIZE)
-
-    if LibSodium.crypto_sign_detached(signature_output_buffer.to_slice, 0, message_buffer.to_slice, message_buffer_size, secret_key.to_slice) != 0
-      raise Error.new("crypto_sign_detached")
-    end
-    signature_output_buffer
-  end
-
-  def self.verify_detached(signature, message, public_key : SignPublicKey)
-    signature_buffer = signature.to_slice
-    message_buffer = message.to_slice
-    message_buffer_size = message_buffer.bytesize
-
-    verified = LibSodium.crypto_sign_verify_detached(signature_buffer.to_slice, message_buffer.to_slice, message_buffer_size, public_key.to_slice)
-    verified.zero?
-  end
 end
 
 if Cox::LibSodium.sodium_init == -1

src/cox/lib_sodium.cr

@@ -108,7 +108,7 @@ module Cox
 
     fun crypto_sign_detached(
       signature_output : Pointer(LibC::UChar),
-      signature_output_size : LibC::ULongLong,
+      signature_output_size : Pointer(LibC::ULongLong),
       message : Pointer(LibC::UChar),
       message_size : LibC::ULongLong,
       secret_key : Pointer(LibC::UChar)

src/cox/secret_key.cr

@@ -48,7 +48,7 @@ module Cox
 
     def decrypt_easy(data : Bytes, nonce : Nonce) : Bytes
       output_size = data.bytesize - MAC_SIZE
-      raise Cox::DecryptionFailed.new("encrypted data too small #{data.bytesize}") if output_size <= 0
+      raise Cox::Error::DecryptionFailed.new("encrypted data too small #{data.bytesize}") if output_size <= 0
       output = Bytes.new output_size
       decrypt_easy(data, output, nonce)
     end
@@ -58,7 +58,7 @@ module Cox
         raise ArgumentError.new("dst.bytesize must be src.bytesize - MAC_SIZE, got #{dst.bytesize}")
       end
       if LibSodium.crypto_secretbox_open_easy(dst, src, src.bytesize, nonce.to_slice, @bytes) != 0
-        raise Cox::DecryptionFailed.new("crypto_secretbox_easy")
+        raise Cox::Error::DecryptionFailed.new("crypto_secretbox_easy")
       end
       dst
     end

src/cox/sign/public_key.cr

@@ -0,0 +1,28 @@
+require "../lib_sodium"
+
+module Cox
+  class Sign::PublicKey < Key
+    property bytes : Bytes
+
+    KEY_SIZE = LibSodium::PUBLIC_SIGN_SIZE
+
+    def initialize(@bytes : Bytes)
+      if bytes.bytesize != KEY_SIZE
+        raise ArgumentError.new("Public key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
+      end
+    end
+
+    def verify_detached(message, sig : Bytes)
+      verify_detached message.to_slice, sig
+    end
+
+    def verify_detached(message : Bytes, sig : Bytes)
+      raise ArgumentError.new("Signature must be #{LibSodium::SIGNATURE_SIZE} bytes, got #{sig.bytesize}")
+
+      v = LibSodium.crypto_sign_verify_detached sig, message, message.bytesize, @bytes
+      if v != 0
+        raise Cox::Error::VerificationFailed.new("crypto_sign_verify_detached")
+      end
+    end
+  end
+end

src/cox/sign/secret_key.cr

@@ -0,0 +1,46 @@
+require "../lib_sodium"
+
+module Cox
+  class Sign::SecretKey < Cox::Key
+    KEY_SIZE = LibSodium::SECRET_SIGN_SIZE
+
+    getter bytes : Bytes
+    getter public_key
+
+    # Generates a new secret/public key pair.
+    def initialize
+      pkey = Bytes.new(Sign::PublicKey::KEY_SIZE)
+      @bytes = Bytes.new(KEY_SIZE)
+      @public_key = PublicKey.new pkey
+      LibSodium.crypto_sign_keypair pkey, @bytes
+    end
+
+    # Use existing Private and Public keys.
+    def initialize(@bytes : Bytes, pkey : Bytes)
+      raise ArgumentError.new("Secret sign key must be #{KEY_SIZE}, got #{@bytes.bytesize}")
+      @public_key = PublicKey.new pkey
+    end
+
+    #    def initialize(@bytes : Bytes)
+    #      if bytes.bytesize != KEY_SIZE
+    #        raise ArgumentError.new("Secret key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
+    #      end
+    # BUG: fix
+    # @public_key = PublicKey.new Bytes.new(100)
+    # raise "Needs crypto_sign_ed25519_sk_to_pk"
+    # Also needs to differentiate from seed as a single parameter
+    #    end
+
+    def sign_detached(message)
+      sign_detached message.to_slice
+    end
+
+    def sign_detached(message : Bytes)
+      sig = Bytes.new(LibSodium::SIGNATURE_SIZE)
+      if LibSodium.crypto_sign_detached(sig, out sig_len, message, message.bytesize, @bytes) != 0
+        raise Error.new("crypto_sign_detached")
+      end
+      sig
+    end
+  end
+end

src/cox/sign_key_pair.cr

@@ -1,24 +0,0 @@
-require "./lib_sodium"
-
-module Cox
-  class SignKeyPair
-    property public : SignPublicKey
-    property secret : SignSecretKey
-
-    def initialize(@public, @secret)
-    end
-
-    def self.new(pub : Bytes, sec : Bytes)
-      new(SignPublicKey.new(pub), SignSecretKey.new(sec))
-    end
-
-    def self.new
-      public_key = Bytes.new(SignPublicKey::KEY_SIZE)
-      secret_key = Bytes.new(SignSecretKey::KEY_SIZE)
-
-      LibSodium.crypto_sign_keypair(public_key.to_unsafe, secret_key.to_unsafe)
-
-      new(public_key, secret_key)
-    end
-  end
-end

src/cox/sign_public_key.cr

@@ -1,15 +0,0 @@
-require "./lib_sodium"
-
-module Cox
-  class SignPublicKey < Key
-    property bytes : Bytes
-
-    KEY_SIZE = LibSodium::PUBLIC_SIGN_SIZE
-
-    def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_SIZE
-        raise ArgumentError.new("Public key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
-      end
-    end
-  end
-end

src/cox/sign_secret_key.cr

@@ -1,15 +0,0 @@
-require "./lib_sodium"
-
-module Cox
-  class SignSecretKey < Key
-    property bytes : Bytes
-
-    KEY_SIZE = LibSodium::SECRET_SIGN_SIZE
-
-    def initialize(@bytes : Bytes)
-      if bytes.bytesize != KEY_SIZE
-        raise ArgumentError.new("Secret key must be #{KEY_SIZE} bytes, got #{bytes.bytesize}")
-      end
-    end
-  end
-end