A5/1 is a shift register based stream cipher which provides privacy for the GSM system. In this paper, we analyse the loading of the secret key and IV during the initialisation process of A5/1. We demonstrate the existence of weak key-IV pairs in the A5/1 cipher due to this loading process; these weak key-IV pairs may generate one, two or three registers containing all-zero values, which may le...

In this paper, we analyze the security of the stream cipher Helix, recently proposed at FSE’03. Helix is a high-speed asynchronous stream cipher, with a built-in MAC functionality. We analyze the differential properties of its keystream generator and describe two new attacks. The first attack requires 2 basic operations and processes only 2 words of chosen plaintext in order to recover the secr...

Abstract. Zorro is an AES-like lightweight block cipher proposed in CHES 2013, which only uses 4 S-boxes per round. The designers showed the resistance of the cipher against various attacks and concluded the cipher has a large security margin. Recently, Guo et. al [1] have given a key recovery attack on full-round Zorro by using the internal differential characteristics. However, the attack onl...

In numerous modern stream ciphers, the internal state consists of a large array of pseudo-random words, and the output key-stream is a relatively simple function of the state. In [16], it was heuristically shown that in various cases this structure may lead to distinguishing attacks on the cipher. In this paper we further investigate this structural attack. We present a rigorous proof of the ma...

Cryptanalysis of cipher text by using evolutionary algorithm has gained so much interest in last few years. This paper demonstrates the use of Binary Particle Swarm Optimization with bit change mutation operator for cryptanalysis of S-DES and then compared the results with Genetic Algorithm. An experimental result shows that Binary PSO performs better than the genetic algorithms for such type o...

Khudra is a lightweight block cipher designed for Field Programmable Gate Array (FPGA) based platforms. The cipher has an 18-round generalized type-2 Feistel structure with 64-bit block size. The key schedule takes 80-bit master key and produces 32-bit round keys performing very simple operations. In this work, we analyze the security of Khudra. We first show that the effective round key length...

While communication infrastructures rapidly intertwine with our daily lives, public understanding of underlying technologies and privacy implications is often limited by their closed-source nature. Lacking the funding and resources of corporations and the intelligence community, developing and expanding this understanding is a sometimes tedious, but nonetheless important process. In this sense,...

This paper presents algorithms for encryption and decryption developed using pseudo random number generator (PRNG) and non-Linear functions. PRNG used in the work are matlab random number generator (RNG) and Linear congruential generator (LCG). The developed algorithms are named according to PRNG used in it. State of PRNG is considered as secret key of the cipher. The encryption schemes have be...

The history of integral cryptanalysis is a little complicated, and the most important papers to study regarding it are not in fact the ones in which it was first defined. We give a brief recap here: In 1997, Daemen, Knudsen, and Rijmen published a paper [3] describing a new cipher. This cipher, SQUARE, was a forerunner of Rijndael [10], the eventual AES, and was designed using the same wide tra...