feature(FakeAuthenticator): add EdDSA credential keys support

Author: santiagorodriguez96

lib/webauthn/fake_authenticator.rb

@@ -85,7 +85,14 @@ def get_assertion(
           extensions: extensions
         ).serialize
 
-        signature = credential_key.sign("SHA256", authenticator_data + client_data_hash)
+        signature_digest_algorithm =
+          case credential_key
+          when OpenSSL::PKey::RSA, OpenSSL::PKey::EC
+            'SHA256'
+          when OpenSSL::PKey::PKey
+            nil
+          end
+        signature = credential_key.sign(signature_digest_algorithm, authenticator_data + client_data_hash)
         credential[:sign_count] += 1
 
         {

lib/webauthn/fake_authenticator/attestation_object.rb

@@ -61,7 +61,7 @@ def authenticator_data
           begin
             credential_data =
               if attested_credential_data
-                { id: credential_id, public_key: credential_key.public_key }
+                { id: credential_id, public_key: credential_public_key }
               end
 
             AuthenticatorData.new(
@@ -76,6 +76,15 @@ def authenticator_data
             )
           end
       end
+
+      def credential_public_key
+        case credential_key
+        when OpenSSL::PKey::RSA, OpenSSL::PKey::EC
+          credential_key.public_key
+        when OpenSSL::PKey::PKey
+          OpenSSL::PKey.read(credential_key.public_to_der)
+        end
+      end
     end
   end
 end

lib/webauthn/fake_authenticator/authenticator_data.rb

@@ -140,7 +140,9 @@ def cose_credential_public_key
 
           key = COSE::Key::EC2.from_pkey(credential[:public_key])
           key.alg = alg[key.crv]
-
+        when OpenSSL::PKey::PKey
+          key = COSE::Key::OKP.from_pkey(credential[:public_key])
+          key.alg = -8
         end
 
         key.serialize