Key-Recovery Attacks on CRAFT and WARP

This paper considers the security of CRAFT and WARP. We present a practical key-recovery attack on full-round CRAFT in the related-key setting with only one differential characteristic, and the theoretical time complexity of the attack is \(2^{36.09}\) full-round encryptions. The attack is verified in practice. The test result indicates that the theoretical analysis is valid, and it takes about 15.69 h to retrieve the key. A full-round key-recovery attack on WARP in the related-key setting is proposed, and the time complexity is \(2^{44.58}\) full-round encryptions. The theoretical attack is implemented on a round-reduced version of WARP, which guarantees validity. Besides, we give a 33-round multiple zero-correlation linear attack on WARP, which is the longest attack on the cipher in the single-key attack setting. We note that the attack results in this paper do not threaten the security of CRAFT and WARP as the designers do not claim security under the related-key attack setting.