Fix KEY_SIZE and NONCE_SIZE for non-ietf salsa/chacha ciphers.

Allow dupping various classes.

README.md

@@ -178,14 +178,14 @@ public_key.verify_detached message, signature
 
 ### Secret Key Encryption
 ```crystal
-key = Sodium::SecretKey.new
+box = Sodium::SecretBox.new
 
 message = "foobar"
-encrypted, nonce = key.encrypt message
+encrypted, nonce = box.encrypt message
 
 # On the other side.
-key = Sodium::SecretKey.new key
-message = key.decrypt encrypted, nonce
+box = Sodium::SecretKey.new key
+message = box.decrypt encrypted, nonce: nonce
 ```
 
 ### Blake2b

spec/sodium/cipher/aead/chalsa_spec.cr

@@ -87,6 +87,18 @@ end
         box.encrypt_detached message.to_slice, nonce: nonce
       end
     end
+
+    it "dups" do
+      box1 = Sodium::Cipher::Aead::{{ name.id }}.new Bytes.new(Sodium::Cipher::Aead::{{ name.id }}::KEY_SIZE)
+      box2 = box1.dup
+
+      key1 = box1.key
+      key2 = box2.key
+      key2.readwrite
+
+      key2.to_slice[0] = 1_u8
+      key1.to_slice[0].should eq 0_u8
+    end
   end
 
   describe Sodium::Cipher::Aead do

spec/sodium/cipher/chalsa_spec.cr

@@ -25,5 +25,16 @@ require "../../../src/sodium/cipher/chalsa"
       cipher2.update(output).should eq data
       cipher2.final.should eq Bytes.new(0)
     end
+
+    it "dups" do
+      cipher1 = Sodium::Cipher::{{ name.id }}.new Bytes.new(Sodium::Cipher::{{ name.id }}::KEY_SIZE)
+      cipher2 = cipher1.dup
+
+      key1 = cipher1.key
+      key2 = cipher2.key
+
+      key2.to_slice[0] = 1_u8
+      key1.to_slice[0].should eq 0_u8
+    end
   end
 {% end %}

spec/sodium/digest/blake2b_spec.cr

@@ -90,4 +90,7 @@ describe Sodium::Digest::Blake2b do
       Sodium::Digest::Blake2b.new personal: Bytes.new(128)
     end
   end
+
+  pending "dups" do
+  end
 end

spec/sodium/nonce_spec.cr

@@ -28,4 +28,12 @@ describe Sodium::Nonce do
     nonce.to_slice.should eq one
     nonce.used?.should be_false
   end
+
+  it "dups" do
+    nonce1 = Sodium::Nonce.zero
+    nonce2 = nonce1.dup
+
+    nonce2.to_slice[0] = 1_u8
+    nonce1.to_slice[0].should eq 0_u8
+  end
 end

src/sodium/cipher/aead/chalsa.cr

@@ -79,6 +79,10 @@ module Sodium::Cipher::Aead
     abstract def decrypt_detached(src : Bytes, dst : Bytes? = nil, *, nonce : Sodium::Nonce, mac : Bytes, additional : String | Bytes | Nil = nil) : Bytes
     protected abstract def key_size : Int32
     protected abstract def mac_size : Int32
+
+    def dup
+      self.class.new @key.dup
+    end
   end
 
   {% for key, val in {"XChaCha20Poly1305Ietf" => "_xchacha20poly1305_ietf"} %}

src/sodium/cipher/chalsa.cr

@@ -12,10 +12,13 @@ module Sodium::Cipher
     # Advanced usage.  Don't touch.
     property offset = 0
 
+    getter! key
+    getter! nonce
+
     def initialize
     end
 
-    def initialize(key, nonce)
+    def initialize(key = nil, nonce = nil)
       self.key = key if key
       self.nonce = nonce if nonce
     end
@@ -45,10 +48,12 @@ module Sodium::Cipher
       update src, Bytes.new(src.bytesize)
     end
 
+    private FINAL_BYTES = Bytes.new 0
+
     # Provided for compatibility with block or tagged ciphers.
     # Stream ciphers don't have additional data.
     def final
-      Bytes.new(0)
+      FINAL_BYTES
     end
 
     # Use as a CSPRNG.
@@ -74,9 +79,15 @@ module Sodium::Cipher
     abstract def update(src : Bytes, dst : Bytes)
     abstract def key_size : Int32
     abstract def nonce_size : Int32
+
+    def dup
+      self.class.new key: @key.try(&.dup), nonce: @nonce.try(&.dup)
+    end
   end
 
-  {% for key, val in {"XSalsa20" => "xsalsa20", "Salsa20" => "salsa20", "XChaCha20" => "xchacha20", "ChaCha20Ietf" => "chacha20_ietf", "ChaCha20" => "chacha20"} %}
+  {% for key, valtup in {"Xchacha16" => {"xchacha16", false}, "XSalsa20" => {"xsalsa20", false}, "Salsa20" => {"salsa20", false}, "XChaCha20" => {"xchacha20", false}, "ChaCha20Ietf" => {"chacha20_ietf", true}, "ChaCha20" => {"chacha20", false}} %}
+    {% val = valtup[0] %}
+    {% ietf = valtup[1] %}
     # 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.
@@ -89,6 +100,9 @@ module Sodium::Cipher
     #
     # 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
+
       # Xor's src with the cipher output and places in dst.
       #
       # src and dst may be the same object but should not overlap.
@@ -106,11 +120,11 @@ module Sodium::Cipher
       end
 
       def key_size : Int32
-        LibSodium.crypto_stream_chacha20_ietf_keybytes.to_i32
+        KEY_SIZE
       end
 
       def nonce_size : Int32
-        LibSodium.crypto_stream_chacha20_ietf_noncebytes.to_i32
+        NONCE_SIZE
       end
     end
   {% end %}

src/sodium/nonce.cr

@@ -44,6 +44,10 @@ module Sodium
       @used = true unless @reusable
     end
 
+    def dup
+      self.class.new @bytes.dup
+    end
+
     module SerializeConverter
       def self.to_json(value : Nonce, json : JSON::Builder)
         json.string Base64.strict_encode(value.to_slice)