v0.1.0

lib/src/algorithms.dart

@@ -0,0 +1,49 @@
+import 'dart:convert';
+
+import 'package:crypto/crypto.dart';
+import 'package:jsonwebtoken/jsonwebtoken.dart';
+
+abstract class JWTAlgorithm {
+  static const HS256 = HS256Algorithm();
+
+  static JWTAlgorithm fromName(String name) {
+    switch (name) {
+      case 'HS256':
+        return JWTAlgorithm.HS256;
+      default:
+        throw JWTInvalidError('unknown algorithm');
+    }
+  }
+
+  const JWTAlgorithm();
+
+  String get name;
+  List<int> sign(String key, List<int> body);
+  bool verify(String key, List<int> body, List<int> signature);
+}
+
+class HS256Algorithm extends JWTAlgorithm {
+  const HS256Algorithm();
+
+  @override
+  String get name => 'HS256';
+
+  @override
+  List<int> sign(String key, List<int> body) {
+    final hmac = Hmac(sha256, utf8.encode(key));
+    return hmac.convert(body).bytes;
+  }
+
+  @override
+  bool verify(String key, List<int> body, List<int> signature) {
+    final actual = sign(key, body);
+
+    if (actual.length != signature.length) return false;
+
+    for (var i = 0; i < actual.length; i++) {
+      if (actual[i] != signature[i]) return false;
+    }
+
+    return true;
+  }
+}