Ed25519 Point Validation

lib/rbnacl.rb

@@ -63,8 +63,9 @@ class BadAuthenticatorError < CryptoError; end
   require "rbnacl/signatures/ed25519/signing_key"
   require "rbnacl/signatures/ed25519/verify_key"
 
-  # Group Elements: Curve25519
+  # Group Elements: Curve25519, Ed25519
   require "rbnacl/group_elements/curve25519"
+  require "rbnacl/group_elements/ed25519"
 
   # One-time Authentication: Poly1305
   require "rbnacl/one_time_auths/poly1305"

lib/rbnacl/group_elements/ed25519.rb

@@ -0,0 +1,37 @@
+# encoding: binary
+# frozen_string_literal: true
+
+module RbNaCl
+  module GroupElements
+    # Points on the Ed25519 elliptic curve
+    #
+    # This class provides low-level operations on Ed25519 curve points,
+    # including point validation.
+    class Ed25519
+      extend Sodium
+
+      sodium_type :core
+      sodium_primitive :ed25519
+
+      sodium_function_with_return_code :core_ed25519_is_valid_point,
+                                        :crypto_core_ed25519_is_valid_point,
+                                        %i[pointer]
+
+      # Number of bytes in an Ed25519 point
+      BYTES = 32
+
+      # Check if a point is valid on the Ed25519 curve
+      #
+      # @param point [String] The point to validate (32 bytes)
+      #
+      # @raise [LengthError] if the point is not 32 bytes
+      #
+      # @return [Boolean] true if the point is valid, false otherwise
+      def self.valid_point?(point)
+        point = point.to_str
+        Util.check_length(point, BYTES, "point")
+        core_ed25519_is_valid_point(point).zero?
+      end
+    end
+  end
+end