lib/cose/mac0.rb in cose-0.8.0 vs lib/cose/mac0.rb in cose-0.9.0

@@ -1,19 +1,42 @@
+# frozen_string_literal: true
+
 require "cbor"
 require "cose/security_message"
+require "openssl"
 
 module COSE
   class Mac0 < SecurityMessage
+    CONTEXT = "MAC0"
+
     attr_reader :payload, :tag
 
     def self.keyword_arguments_for_initialize(decoded)
-      { payload: CBOR.decode(decoded[0]), tag: decoded[1] }
+      { payload: decoded[0], tag: decoded[1] }
     end
 
+    def self.tag
+      17
+    end
+
     def initialize(payload:, tag:, **keyword_arguments)
       super(**keyword_arguments)
 
       @payload = payload
       @tag = tag
+    end
+
+    def verify(key, external_aad = nil)
+      tag == algorithm.mac(key.k, data(external_aad)) || raise(COSE::Error, "Mac0 verification failed")
+    end
+
+    private
+
+    def data(external_aad = nil)
+      CBOR.encode([context, serialized_map(protected_headers), external_aad || zero_length_bin_string, payload])
+    end
+
+    def context
+      CONTEXT
     end
   end
 end