title: Reliable way to tell if wrong key is used in aes256 decryption
body: <p>I have some code that I am using to encrypt and decrypt some strings in an ios application.  The code involves the use of CCCrypt.  Is there a reliable way to test the validity of a key used without actually storing the key anywhere?  From my research it seems as though the only way to come close to telling if the key is valid is by using key lengths and key hashes.  Can anyone guide me in the proper direction for this?</p>