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HAS-160, a Korean hash standard, has been widely used in the Korean industry. This paper aims to re-evaluate the security of HAS-160 in the encryption mode, a block cipher with the 512-bit key size and the 160-bit plaintext block size. A previous attack is based on a 71-round related-key distinguisher with probability 2-304. Using some delicate properties of HAS-160 and employing a bit-fixing technique, we present a 72-round related-key rectangle distinguisher with probability 2-290 in this paper. Based on this new distinguisher, two key recovery attacks on the encryption mode of the full 80-round HAS-160 are performed, which improve the earlier results. The attacks presented in this paper are the best known results on HAS-160 in the encryption mode in terms of the number of attack rounds and the efficiency of attacks. [ABSTRACT FROM AUTHOR]

This paper proposes an efficient masking method for the block cipher SEED that is standardized in Korea. The nonlinear parts of SEED consist of two S-boxes and modular additions. However, the masked version of these nonlinear parts requires excessive RAM usage and a large number of operations. Protecting SEED by the general masking method requires 512 bytes of RAM corresponding to masked S-boxes and a large number of operations corresponding to the masked addition. This paper proposes a new-style masked S-box which can reduce the amount of operations of the masking addition process as well as the RAM usage. The proposed masked SEED, equipped with the new-style masked S-box, reduces the RAM requirements to 288 bytes, and it also reduces the processing time by 38% compared with the masked SEED using the general masked S-box. The proposed method also applies to other block ciphers with the same nonlinear operations. [ABSTRACT FROM AUTHOR]