On the Notions of PRP-RKA, KR and KR-RKA for Block Ciphers

Security of a modern block cipher is commonly measured in terms of its resistance to known attacks. While the provable security approach to block ciphers dates back to the first CRYPTO conference (1981), analysis of modern block cipher proposals typically do not ben- efit fully from this besides the proof of security for DESX by Kilian and Rogaway, and recent work on the notions of PRP-RKA initiated by Bel- lare and Kohno. We consider the security of recently proposed PRP-RKA secure block ciphers. We discuss implications of the proven theorems and how they relate to existing types of attacks on block ciphers. Our results are the first known cryptanalysis of these provably secure ciphers.