Support EdDSA for JWT (#7)

lib/src/algorithms.dart

@@ -3,6 +3,7 @@ import 'dart:typed_data';
 
 import 'package:crypto/crypto.dart';
 import 'package:pointycastle/pointycastle.dart' as pc;
+import 'package:ed25519_edwards/ed25519_edwards.dart' as ed;
 
 import 'errors.dart';
 import 'keys.dart';
@@ -36,6 +37,9 @@ abstract class JWTAlgorithm {
   /// ECDSA using P-512 curve and SHA-512 hash algorithm
   static const ES512 = _ECDSAAlgorithm('ES512');
 
+  /// EdDSA using Ed25519 curve algorithm
+  static const Ed25519 = _EdDSAAlgorithm('EdDSA');
+
   /// Return the `JWTAlgorithm` from his string name
   static JWTAlgorithm fromName(String name) {
     switch (name) {
@@ -57,6 +61,8 @@ abstract class JWTAlgorithm {
         return JWTAlgorithm.ES384;
       case 'ES512':
         return JWTAlgorithm.ES512;
+      case 'EdDSA':
+        return JWTAlgorithm.Ed25519;
       default:
         throw JWTInvalidError('unknown algorithm');
     }
@@ -78,6 +84,35 @@ abstract class JWTAlgorithm {
   bool verify(Key key, Uint8List body, Uint8List signature);
 }
 
+class _EdDSAAlgorithm extends JWTAlgorithm {
+  final String _name;
+
+  const _EdDSAAlgorithm(this._name);
+
+  @override
+  String get name => _name;
+
+  @override
+  Uint8List sign(Key key, Uint8List body) {
+    assert(key is EdDSAPrivateKey, 'key must be a EdDSAPrivateKey');
+    final privateKey = key as EdDSAPrivateKey;
+
+    return ed.sign(privateKey.key, body);
+  }
+
+  @override
+  bool verify(Key key, Uint8List body, Uint8List signature) {
+    assert(key is EdDSAPublicKey, 'key must be a EdDSAPublicKey');
+    final publicKey = key as EdDSAPublicKey;
+
+    try {
+      return ed.verify(publicKey.key, body, signature);
+    } catch (ex) {
+      return false;
+    }
+  }
+}
+
 class _HMACAlgorithm extends JWTAlgorithm {
   final String _name;
 

lib/src/jwt.dart

@@ -13,6 +13,7 @@ class JWT {
   /// - SecretKey with HMAC algorithm
   /// - RSAPublicKey with RSA algorithm
   /// - ECPublicKey with ECDSA algorithm
+  /// - EdDSAPublicKey with EdDSA algorithm
   static JWT verify(
     String token,
     Key key, {
@@ -166,6 +167,7 @@ class JWT {
   /// - SecretKey with HMAC algorithm
   /// - RSAPrivateKey with RSA algorithm
   /// - ECPrivateKey with ECDSA algorithm
+  /// - EdDSAPrivateKey with EdDSA algorithm
   String sign(
     Key key, {
     JWTAlgorithm algorithm = JWTAlgorithm.HS256,
@@ -210,7 +212,7 @@ class JWT {
       );
     }
 
-    final body = '${b64Header}.${b64Payload}';
+    final body = '$b64Header.$b64Payload';
     final signature = base64Unpadded(
       base64Url.encode(
         algorithm.sign(

lib/src/keys.dart

@@ -1,4 +1,5 @@
 import 'package:pointycastle/pointycastle.dart' as pc;
+import 'package:ed25519_edwards/ed25519_edwards.dart' as ed;
 
 import 'errors.dart';
 import 'parser.dart';
@@ -12,6 +13,24 @@ class SecretKey extends Key {
   SecretKey(this.key);
 }
 
+/// For EdDSA algorithm, in sign method
+class EdDSAPrivateKey extends Key {
+  late ed.PrivateKey key;
+
+  EdDSAPrivateKey(List<int> bytes) {
+    key = ed.PrivateKey(bytes);
+  }
+}
+
+/// For EdDSA algorithm, in verify method
+class EdDSAPublicKey extends Key {
+  late ed.PublicKey key;
+
+  EdDSAPublicKey(List<int> bytes) {
+    key = ed.PublicKey(bytes);
+  }
+}
+
 /// For RSA algorithm, in sign method
 class RSAPrivateKey extends Key {
   late pc.RSAPrivateKey key;