EnRUPT – The Simpler The Better

An interesting new related-key attack has been found that can break enRUPT32x1 (block cipher mode) if the attacker is allowed to modify the key and request a sufficiently large number of chosen plaintext/ciphertext pairs. We will comment on it after a thorough investigation of the attack itself, how it got overlooked by our tools and what is required to prevent it in the future by detecting such vulnerabilities with automated cryptanalysis.

Interestingly enough, this attack also breaks XXTEA but without the need for related keys. Also, according to the author of the attack, it cannot be applied to the stream cipher or stream hashing modes of EnRUPT including the ïrRUPT mode submitted to the SHA-3 competition.