Clock control is one of the mechanisms employed to introduce non-linearity into key stream generators built from linear feedback shift registers. The earliest devices were built from stop-and-go registers while the most recent example, the Shrinking Generator proposed in [2], has an irregular clocking scheme where the number of steps between successive outputs is linked to the length of zero-ru...

We describe a solution for physically obfuscating the representation of a cipher, to augment chips resistance against physical threats, by combining ideas from masking techniques and Physical Obfuscated Keys (POKs). With embedded chips – like RFID tags – as main motivation, we apply this strategy to the representation of a Linear Feedback Shift Register (LFSR). The application of this technique...

Pseudorandom binary sequences are widely applied to the various engineering domains such as biology system control, spread spectrum communications and cryptography [1-3]. Particularly, the security of cryptographic systems is strongly contingent on the pseudorandomness of the key stream [3]. Depending on the cryptography application, a sequence is required to present many properties so as to be...

The main aim of this chapter is to provide a security evaluation method based on fuzzy logic “for a pseudo-random sequences used (mainly) in stream cipher systems. The designed Fuzzy rules consider two main parameters, which are the length of the maximum period of the key sequence obtained from Linear Feedback Shift Register (LFSR) and the entropy of the result in sequences obtained from differ...

In spread spectrum systems, pseudo-random (PN) sequences are used to spread the data bits. There are various type of PN sequences are available with good correlation properties, most of which are generated by Linear Feedback Shift Register (LFSR). In this paper we describe the generation pseudo chaotic sequences (PCS) and conventional PN sequences and its correlation properties. Here, pseudo-ch...

KATAN and KTANTAN are two lightweight families of hardware oriented block ciphers proposed by Cannière et al. at CHES 2009. They have different versions of 32-, 48and 64-bit state, all of which work with an 80-bit key. Inspired by the Trivium stream cipher, these families have an innovative structure based on two non-linear feedback shift registers. Such a structure attracts the attention of cr...

SUMMARY Spreading sequences with appropriate negative auto-correlation can reduce average multiple access interference (MAI) in asyn-chronous DS/CDMA systems compared with the conventional Gold Sequences generated by linear feedback shift registers (LFSRs). We design spreading sequences with negative auto-correlation based on Gold sequences and the chaos theory for the Bernoulli map. By compute...

We give the results of a computer search for maximally equidistributed combined linear feedback shift register (or Tausworthe) random number generators, whose components are trinomials of degrees slightly less than 32 or 64. These generators are fast and have good statistical properties.

In this paper, a lemma in algebraic coding theory is established, which is frequently appeared in the encoding and decoding for algebraic codes such as Reed–Solomon codes and algebraic geometry codes. This lemma states that two vector spaces, one corresponds to information symbols and the other is indexed by the support of Gröbner basis, are canonically isomorphic, and moreover, the isomorphism...

Many proposals of pseudorandom sequence generators and stream ciphers employ linear feedback shift registers with dynamic feedback (DLFSR) as the main module to increase the period and linear span of the involved msequences. In this paper, we present a theoretical model that allows the design of longer sequences with higher linear span than in previous DLFSR schemes. The model determines the co...