Cryptanalysis of Rijmen-Preneel Trapdoor Ciphers

Rijmen and Preneel recently proposed for the rst time a family of trapdoor block ciphers 8]. In this family of ciphers, a trapdoor is hidden in S-boxes and is claimed to be undetectable in 8] for properly chosen parameters. Given the trapdoor, the secret key (used for encryption and decryption) can be recovered easily by applying Matsui's linear cryptanalysis 6]. In this paper, we break this family of trapdoor block ciphers by developing an attack on the S-boxes. We show how to nd the trapdoor in the S-boxes and demonstrate that it is impossible to adjust the parameters of the S-boxes such that detecting the trapdoor is di cult meanwhile nding the secret key by trapdoor information is easy.

• Type: Conference
• Year: 1998
• Where: ASIACRYPT
• Authors: Hongjun Wu, Feng Bao, Robert H. Deng, Qin-Zhong Ye
• Keywords: ASIACRYPT 1998, Cryptology, Secret Key, Trapdoor, Trapdoor Block Ciphers