base64 url encode/decode heleprs (#1038)

src/Core/Services/TokenService.cs

@@ -134,7 +134,7 @@ namespace Bit.Core.Services
             {
                 throw new InvalidOperationException("JWT must have 3 parts.");
             }
-            var decodedBytes = Base64UrlDecode(parts[1]);
+            var decodedBytes = CoreHelpers.Base64UrlDecode(parts[1]);
             if (decodedBytes == null || decodedBytes.Length < 1)
             {
                 throw new InvalidOperationException("Cannot decode the token.");
@@ -230,32 +230,6 @@ namespace Bit.Core.Services
             return decoded["iss"].Value<string>();
         }
 
-        private byte[] Base64UrlDecode(string input)
-        {
-            var output = input;
-            // 62nd char of encoding
-            output = output.Replace('-', '+');
-            // 63rd char of encoding
-            output = output.Replace('_', '/');
-            // Pad with trailing '='s
-            switch (output.Length % 4)
-            {
-                case 0:
-                    // No pad chars in this case
-                    break;
-                case 2:
-                    // Two pad chars
-                    output += "=="; break;
-                case 3:
-                    // One pad char
-                    output += "="; break;
-                default:
-                    throw new InvalidOperationException("Illegal base64url string!");
-            }
-            // Standard base64 decoder
-            return Convert.FromBase64String(output);
-        }
-
         private async Task<bool> SkipTokenStorage()
         {
             var timeout = await _storageService.GetAsync<int?>(Constants.VaultTimeoutKey);

src/Core/Utilities/CoreHelpers.cs

@@ -209,5 +209,40 @@ namespace Bit.Core.Utilities
             }
             return JsonConvert.DeserializeObject<T>(json, jsonSerializationSettings);
         }
+
+        public static string Base64UrlEncode(byte[] input)
+        {
+            var output = Convert.ToBase64String(input)
+                .Replace('+', '-')
+                .Replace('/', '_')
+                .Replace("=", string.Empty);
+            return output;
+        }
+
+        public static byte[] Base64UrlDecode(string input)
+        {
+            var output = input;
+            // 62nd char of encoding
+            output = output.Replace('-', '+');
+            // 63rd char of encoding
+            output = output.Replace('_', '/');
+            // Pad with trailing '='s
+            switch (output.Length % 4)
+            {
+                case 0:
+                    // No pad chars in this case
+                    break;
+                case 2:
+                    // Two pad chars
+                    output += "=="; break;
+                case 3:
+                    // One pad char
+                    output += "="; break;
+                default:
+                    throw new InvalidOperationException("Illegal base64url string!");
+            }
+            // Standard base64 decoder
+            return Convert.FromBase64String(output);
+        }
     }
 }