try decrypt

Pilz.Cryptography/AESStringCrypter.cs

@@ -64,9 +64,16 @@ namespace Pilz.Cryptography
         }
 
         public string Decrypt(string encryptedValue)
+        {
+            try
             {
                 return DecryptStringFromBytes_Aes(Convert.FromBase64String(encryptedValue), GetKey(), GetIV());
             }
+            catch (CryptographicException)
+            {
+                return string.Empty;
+            }
+        }
 
         public static string Decrypt(string encryptedValue, string key, string iv)
         {
@@ -75,9 +82,16 @@ namespace Pilz.Cryptography
         }
 
         public string Encrypt(string plainValue)
+        {
+            try
             {
                 return Convert.ToBase64String(EncryptStringToBytes_Aes(plainValue, GetKey(), GetIV()));
             }
+            catch (CryptographicException)
+            {
+                return string.Empty;
+            }
+        }
 
         public static string Encrypt(string plainValue, string key, string iv)
         {