From power series expansions of functions on curves over finite fields, one can obtain sequences with perfect or almost perfect linear complexity profile. It has been suggested by various authors to use such sequences as key streams for stream ciphers. In this work, we show how long parts of such sequences can be computed efficiently from short ones. Such sequences should therefore considered t...

The autocorrelation of a key stream sequence in a stream cipher is an important cryptographic property. This paper proposes two constructions of binary interleaved sequences of period 4N by selecting appropriate shift sequences, subsequences and complement sequences. And the autocorrelation functions of new sequences are given. The results show that these sequences have low autocorrelation unde...

Trivium is a bit-based stream cipher in the final portfolio of the eSTREAM project. In this paper, we apply the algebraic attack approach of Berbain et al. to Trivium-like ciphers and perform new analyses on them. We demonstrate a new algebraic attack on Bivium-A. This attack requires less time and memory than previous techniques to recover Bivium-A’s initial state. Though our attacks on Bivium...

We present a cryptographic module that can be used both as a cryptographic hash function and as a stream cipher. High performance is achieved through a combination of low work-factor and a high degree of parallelism. Throughputs of 5.1 bits/cycle for the hashing mode and 4.7 bits/cycle for the stream cipher mode are demonstrated on a commercially available VLIW micro-processor.

We present a practical attack on the Panama hash function that generates a collision in 2 evaluations of the state updating function. Our attack improves that of Rijmen and coworkers that had a complexity 2, too high to produce a collision in practice. This improvement comes mainly from the use of techniques to transfer conditions on the state to message words instead of trying many message pai...

Highly nonlinear Boolean functions occupy an important p o-sition in the design of secure block as well as stream ciphers. This paper proves two n e w l o wer bounds on the nonlinearity of Boolean functions. Based on the study of these new lower bounds, we introduce a class of highly nonlinear Boolean functions on odd dimensional spaces and show examples of such functions.

Armknecht and Mikhalev proposed a new stream cipher ‘Sprout’ based on the design specification of the stream cipher, Grain-128a. Sprout has shorter state size than Grain family with a round key function. The output of the round key function is XOR’ed with the feedback bit of the NFSR of the cipher. In this paper, we propose a new fault attack on Sprout by injecting a single bit fault after the ...

In this paper we present two new n-quasigroup stream ciphers based on new n-quasigroup encryption scheme. Also, we present a practical implementation of these ciphers that has very good cryptographic properties. The implementation is based on a design concept of mixing two ”incompatible” group operations on the set Z28 .

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...

This paper looks at the possibility of combining a block cipher and a stream cipher to get a strong hybrid cipher. It includes two specific proposals for combining AES-128 and RC4-128 to get a cipher that takes a 256-bit key and is significantly faster than AES-256, and arguably more secure. One is immune to algebraic attacks.