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

@@ -1,26 +1,71 @@
+# frozen_string_literal: true
+
 require "cbor"
+require "cose/algorithm"
+require "cose/error"
+require "cose/security_message/headers"
 
 module COSE
   class SecurityMessage
+    ZERO_LENGTH_BIN_STRING = "".b
+
     attr_reader :protected_headers, :unprotected_headers
 
     def self.deserialize(cbor)
       decoded = CBOR.decode(cbor)
 
-      if decoded.respond_to?(:value)
+      if decoded.is_a?(CBOR::Tagged)
+        if respond_to?(:tag) && tag != decoded.tag
+          raise(COSE::Error, "Invalid CBOR tag")
+        end
+
         decoded = decoded.value
       end
 
+      from_array(decoded)
+    end
+
+    def self.from_array(array)
       new(
-        protected_headers: CBOR.decode(decoded[0]),
-        unprotected_headers: decoded[1],
-        **keyword_arguments_for_initialize(decoded[2..-1])
+        protected_headers: deserialize_headers(array[0]),
+        unprotected_headers: array[1],
+        **keyword_arguments_for_initialize(array[2..-1])
       )
     end
 
+    def self.deserialize_headers(data)
+      if data == ZERO_LENGTH_BIN_STRING
+        {}
+      else
+        CBOR.decode(data)
+      end
+    end
+
     def initialize(protected_headers:, unprotected_headers:)
       @protected_headers = protected_headers
       @unprotected_headers = unprotected_headers
+    end
+
+    def algorithm
+      @algorithm ||= COSE::Algorithm.find(headers.alg) || raise(COSE::Error, "Unsupported algorithm '#{headers.alg}'")
+    end
+
+    def headers
+      @headers ||= Headers.new(protected_headers, unprotected_headers)
+    end
+
+    private
+
+    def serialized_map(map)
+      if map && !map.empty?
+        map.to_cbor
+      else
+        zero_length_bin_string
+      end
+    end
+
+    def zero_length_bin_string
+      ZERO_LENGTH_BIN_STRING
     end
   end
 end