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Abstract. TWINE is a lightweight block cipher proposed at ECRYPT Workshop on Lightweight Cryptography 2011, Belgium. The cipher consists of 36 rounds and has two versions TWINE-80 and TWINE-128 supporting key lengths of 80 and 128 bits, respectively. The block length of the two versions is 64-bit. In this paper, we present the first single-key attacks on the both versions of the cipher. In these attacks, we use the recently developed biclique technique. The complexities of the attacks on TWINE-80 and TWINE-128 are 2 79.10 and 2 126.82 respectively and the data requirement for the two attacks is 2 60 .

Abstract. In this paper, we improve the impossible differential attack on 20-round LBlock given in the design paper of the LBlock cipher. Using relations between the round keys we attack on 21-round and 22-round LBlock with a complexity of 2 69.5 and 2 79.28 encryptions respectively. We use the same 14-round impossible differential characteristic observed by the designers to attack on 21 rounds and another 14-round impossible differential characteristic to attack on 22 rounds of LBlock.