Making Verify() public (#52)

* Refactoring Decode(), extracting private Verify() * Making Verify() public, reodering parameters, adding xml doc
jwt-dotnet · Sep 15, 2016 · 87700ef · 87700ef
1 parent d848369
commit 87700ef
Showing 1 changed file with 39 additions and 26 deletions.
diff --git a/JWT/JWT.cs b/JWT/JWT.cs
@@ -128,25 +128,13 @@ public static string Decode(string token, byte[] key, bool verify = true)
             {
                 throw new ArgumentException("Token must consist from 3 delimited by dot parts");
             }
-            var header = parts[0];
-            var payload = parts[1];
-            var crypto = Base64UrlDecode(parts[2]);
 
-            var headerJson = Encoding.UTF8.GetString(Base64UrlDecode(header));
+            var payload = parts[1];
             var payloadJson = Encoding.UTF8.GetString(Base64UrlDecode(payload));
 
-            var headerData = JsonSerializer.Deserialize<Dictionary<string, object>>(headerJson);
-
             if (verify)
             {
-                var bytesToSign = Encoding.UTF8.GetBytes(string.Concat(header, ".", payload));
-                var algorithm = (string)headerData["alg"];
-
-                var signature = HashAlgorithms[GetHashAlgorithm(algorithm)](key, bytesToSign);
-                var decodedCrypto = Convert.ToBase64String(crypto);
-                var decodedSignature = Convert.ToBase64String(signature);
-
-                Verify(decodedCrypto, decodedSignature, payloadJson);
+                Verify(payload, payloadJson, parts, key);
             }
 
             return payloadJson;
@@ -239,18 +227,15 @@ public static byte[] Base64UrlDecode(string input)
             return converted;
         }
 
-        private static JwtHashAlgorithm GetHashAlgorithm(string algorithm)
-        {
-            switch (algorithm)
-            {
-                case "HS256": return JwtHashAlgorithm.HS256;
-                case "HS384": return JwtHashAlgorithm.HS384;
-                case "HS512": return JwtHashAlgorithm.HS512;
-                default: throw new SignatureVerificationException("Algorithm not supported.");
-            }
-        }
-
-        private static void Verify(string decodedCrypto, string decodedSignature, string payloadJson)
+        /// <summary>
+        /// Given the JWT, verifies it.
+        /// </summary>
+        /// <param name="payloadJson">>An arbitrary payload (already serialized to JSON).</param>
+        /// <param name="decodedCrypto">Decoded body</param>
+        /// <param name="decodedSignature">Decoded signature</param>
+        /// <exception cref="SignatureVerificationException">The signature is invalid.</exception>
+        /// <exception cref="TokenExpiredException">The token has expired.</exception>
+        public static void Verify(string payloadJson, string decodedCrypto, string decodedSignature)
         {
             if (decodedCrypto != decodedSignature)
             {
@@ -279,5 +264,33 @@ private static void Verify(string decodedCrypto, string decodedSignature, string
                 throw new TokenExpiredException("Token has expired.");
             }
         }
+
+        private static void Verify(string payload, string payloadJson, string[] parts, byte[] key)
+        {
+            var crypto = Base64UrlDecode(parts[2]);
+            var decodedCrypto = Convert.ToBase64String(crypto);
+
+            var header = parts[0];
+            var headerJson = Encoding.UTF8.GetString(Base64UrlDecode(header));
+            var headerData = JsonSerializer.Deserialize<Dictionary<string, object>>(headerJson);
+            var algorithm = (string)headerData["alg"];
+
+            var bytesToSign = Encoding.UTF8.GetBytes(string.Concat(header, ".", payload));
+            var signatureData = HashAlgorithms[GetHashAlgorithm(algorithm)](key, bytesToSign);
+            var decodedSignature = Convert.ToBase64String(signatureData);
+
+            Verify(payloadJson, decodedCrypto, decodedSignature);
+        }
+
+        private static JwtHashAlgorithm GetHashAlgorithm(string algorithm)
+        {
+            switch (algorithm)
+            {
+                case "HS256": return JwtHashAlgorithm.HS256;
+                case "HS384": return JwtHashAlgorithm.HS384;
+                case "HS512": return JwtHashAlgorithm.HS512;
+                default: throw new SignatureVerificationException("Algorithm not supported.");
+            }
+        }
     }
 }