Tightness of the Security Bound of CENC

CENC (Cipher-based ENCryption) is the recently designed encryption mode for blockciphers. It is provably secure with beyond the birthday bound. In this note, we present a simple distinguishing attack on CENC, and show that the attack is the best attack for some parameter. This proves the tightness of the security bound, and gives a partial answer to the open question posed at FSE 2006. Key words: Encryption mode, blockcipher, CENC, provable security

• Type: Conference
• Year: 2007
• Where: DAGSTUHL
• Authors: Tetsu Iwata
• Keywords: Cipher-based ENCryption, DAGSTUHL 2007, Encryption Mode, Simple Distinguishing Attack, Software Engineering