GOST block cipher designed in the 1970s and published in 1989 as the Soviet and Russian standard GOST 28147-89. In order to enhance the security of GOST block cipher after proposing various attacks on it, designers published a modified version of GOST, namely GOST2, in 2015 which has a new key schedule and explicit choice for S-boxes. In this paper, by using three exactly identical portions of ...

in this paper, we show how to obtain suitable differential charactristics for block ciphers with neural networks. we represent the operations of a block cipher, regarding their differential characteristics, through a directed weighted graph. in this way, the problem of finding the best differential characteristic for a block cipher reduces to the problem of finding the minimum-weight multi-path...

Block cipher system is generally used to encrypt a block of message instead of character by character encryption. Block cipher produces more complexity than stream cipher system. The complexity of block cipher can be increases drastically when we use the binary tree concept for encryption of the message. In this paper, we provide an approach which increases the complexity of the block cipher sy...

This paper studies how to build a 2n-bit block cipher which is hard to distinguish from a truly random permutation against attacks with q ≈ 2 queries, i.e., birthday attacks. Unlike previous approaches using pseudorandom functions, we present a simple and efficient proposal using a tweakable block cipher as an internal module. Our proposal is provably secure against birthday attacks, if underly...

We analyze the security of elastic block ciphers in general to show that an attack on an elastic version of block cipher implies a polynomial time related attack on the fixed-length version of the block cipher. We relate the security of the elastic version of a block cipher to the fixed-length version by forming a reduction between the versions. Our method is independent of the specific block c...

A block cipher, such as the DES cipher, is used to encrypt binary plaintext in discrete blocks of length n using a key of length m, to form ciphertext blocks of length n. A block cipher is said to satisfy the strict key avalanche criterion if a one bit change in the key causes on the average one half of the ciphertext bit positions to change. In this paper the importance of the strict key avala...

An earlier paper by the same author suggested combining a block cipher and a stream cipher to get a strong hybrid cipher. This paper proposes a specific cipher based on those ideas, using the HC-128 stream cipher and a tweakable block cipher based on Serpent. Table of

The idea of double block length hashing is to construct a compression function on 2n bits using a block cipher with an n-bit block size. All optimally secure double length hash functions known in the literature employ a cipher with a key space of double block size, 2n-bit. On the other hand, no optimally secure compression functions built from a cipher with an n-bit key space are known. Our wor...

Given a block cipher of length L Cook’s elastic cipher allows to encrypt messages of variable length from L to 2L. Given some conditions on the key schedule, Cook’s elastic cipher is secure against any key recovery attack if the underlying block cipher is, and it achieves complete diffusion in at most q+1 rounds if the underlying block cipher achieves it in q rounds. We extend Cook’s constructi...