Binary sequences are the most fundamental random numbers and have been extensively used in several applications such as spread-spectrum CDMA communications and cryptosystems. M-sequences, Kasami sequences, and Gold sequences, all of which can be generated by linear feedback shift registers (LFSRs), are well known as conventional binary sequences [1]. It is also well known that chaos phenomena c...

The shrinking generator is a well-known keystream generator composed of two linear feedback shift registers, LFSR1 and LFSR2, where LFSR1 is clock-controlled according to regularly clocked LFSR2. A probabilistic analysis of the shrinking generator which shows that this generator can be vulnerable to a specific fast correlation attack is conducted. The first stage of the attack is based on a rec...

We propose a novel system for optical encryption based on an optical XOR and optical Linear Feedback Shift Register (oLFSRs). Though we choose LFSR for its ability to process optical signals at line rate, we consider the fact that it offers no cryptographic security. To address the security shortfall, we propose implementation of parallel oLFSRs, whereby the resulting key-stream at line rate is...

In this paper we show that an accumulator can be modified to behave as a Non-Linear Feedback Shft Register suitable for test response compaction. The hardware required for this modification is less than that required to mod& a register to a Multiple Input Linear Feedback Shgt Register, MISR. We show with experiments on ISCAS’85, ISCAS’89 benchmark circuits and various types of multipliers that ...

This paper presents Dragon, a new stream cipher constructed using a single word based non-linear feedback shift register and a nonlinear filter function with memory. Dragon uses a variable length key and initialisation vector of 128 or 256 bits, and produces 64 bits of keystream per iteration. At the heart of Dragon are two highly optimised 8 × 32 s-boxes. Dragon uses simple operations on 32-bi...

In their paper, G.Gong and S.Q.Jiang construct a new pseudorandom sequence generator by using two ternary linear feedback shift registers (LFSR). The new generator is called an editing generator which a combined model of the clock-controlled generator and the shrinking generator. For a special case (Both the base sequence and the control sequence are mm-sequence of degree n), the period, linear...

It is well known that in order to build linear scramblers and stream ciphers that are robust against correlation-based reconstruction, primitive polynomials which do not have sparse multiples of moderate degrees must be used. In this paper, the existence and density of such ‘good primitive polynomials’ are studied. Two theoretical lower bounds on the degree d of the primitive polynomial are der...

Most stream ciphers based on linear feedback shift registers (LFSR) are vulnerable to recent algebraic attacks. In this survey paper, we describe generic attacks: existence of algebraic equations and fast algebraic attacks. The generic attacks only states the existence and gives the upper bound of the complexity. Thus we should find good algebraic equations, case by case, in order to apply the ...

The authors prove that the probability of choosing a nonlinear filter of m-sequences with optimal properties, that is, maximum period and maximum linear complexity, tends assymptotically to 1 as the linear feedback shift register length increases. Pseudorandom sequence generators have multiple applications in radar systems, simulation, error-correcting codes, spread-spectrum communication syste...

We consider the problem of efficiently generating sequences in hardware for use in certain cryptographic algorithms. The conventional method of doing this is to use a counter. We show that sequences generated by linear feedback shift registers (LFSRs) can be tailored to suit the appropriate algorithms. For hardware implementation, this reduces both time and chip area. As a result, we are able t...