lib/cose/sign1.rb in cose-0.8.0 vs lib/cose/sign1.rb in cose-0.9.0

@@ -1,19 +1,42 @@
+# frozen_string_literal: true
+
 require "cbor"
+require "cose/error"
 require "cose/security_message"
 
 module COSE
   class Sign1 < SecurityMessage
+    CONTEXT = "Signature1"
+
     attr_reader :payload, :signature
 
     def self.keyword_arguments_for_initialize(decoded)
-      { payload: CBOR.decode(decoded[0]), signature: decoded[1] }
+      { payload: decoded[0], signature: decoded[1] }
     end
 
+    def self.tag
+      18
+    end
+
     def initialize(payload:, signature:, **keyword_arguments)
       super(**keyword_arguments)
 
       @payload = payload
       @signature = signature
+    end
+
+    def verify(key, external_aad = nil)
+      if key.kid == headers.kid
+        algorithm.verify(key, signature, verification_data(external_aad))
+      else
+        raise(COSE::Error, "Non matching kid")
+      end
+    end
+
+    private
+
+    def verification_data(external_aad = nil)
+      CBOR.encode([CONTEXT, serialized_map(protected_headers), external_aad || ZERO_LENGTH_BIN_STRING, payload])
     end
   end
 end