x25519.rb in x25519-1.0.0

- old
+ new

@@ -4,10 +4,11 @@
 
 require "x25519/version"
 
 require "x25519/montgomery_u"
 require "x25519/scalar"
+require "x25519/test_vectors"
 
 # Native extension backends
 require "x25519_ref10"
 require "x25519_precomputed"
 
@@ -16,18 +17,17 @@
   module_function
 
   # Size of an X25519 key (public or private) in bytes
   KEY_SIZE = 32
 
+  # ref10 is the default provider
+  @provider = X25519::Provider::Ref10
+
   # X25519::Precomputed requires a 4th generation Intel Core CPU or newer,
   # so only enable it if we detect we're on a supported platform. Otherwise,
   # fall back to the ref10 portable C implementation.
-  @provider = if X25519::Precomputed.available?
-                X25519::Precomputed
-              else
-                X25519::Ref10
-              end
+  @provider = X25519::Provider::Precomputed if X25519::Provider::Precomputed.available?
 
   # Selected provider based on the logic above
   def provider
     @provider
   end
@@ -40,15 +40,31 @@
   #
   # @return [String] resulting point, serialized as bytes
   def diffie_hellman(scalar_bytes, montgomery_u_bytes)
     validate_key_bytes(scalar_bytes)
     validate_key_bytes(montgomery_u_bytes)
-    X25519.provider.multiply(scalar_bytes, montgomery_u_bytes)
+    X25519.provider.scalarmult(scalar_bytes, montgomery_u_bytes)
   end
 
   # Ensure a serialized key meets the requirements
   def validate_key_bytes(key_bytes)
     raise TypeError, "expected String, got #{key_bytes.class}" unless key_bytes.is_a?(String)
     return true if key_bytes.bytesize == KEY_SIZE
     raise ArgumentError, "expected #{KEY_SIZE}-byte String, got #{key_bytes.bytesize}"
   end
+
+  # Perform a self-test to ensure the selected provider is working
+  def self_test
+    X25519::TestVectors::VARIABLE_BASE.each do |v|
+      shared_secret = provider.scalarmult([v.scalar].pack("H*"), [v.input_coord].pack("H*"))
+      raise "self test failed!" unless shared_secret.unpack("H*").first == v.output_coord
+    end
+
+    X25519::TestVectors::FIXED_BASE.each do |v|
+      public_key = provider.scalarmult_base([v.scalar].pack("H*"))
+      raise "self test failed!" unless public_key.unpack("H*").first == v.output_coord
+    end
+  end
 end
+
+# Automatically run self-test when library loads
+X25519.self_test