We study the asymptotic behavior of stream cipher security measures associated with classes of sequence generators such as linear feedback shift registers and feedback with carry shift registers. For nonperiodic sequences we consider normalized measures and study the set of accumulation points for a fixed sequence. We see that the the set of accumulation points is always a closed subinterval of...

A d-feedback-with-carry shift register (d-FCSR) is a finite state machine, similar to a linear feedback shift register, in which a small amount of memory and a delay (by d-clock cycles) is used in the feedback algorithm (see [4, 5]). The output sequences of these simple devices may be described using arithmetic in a ramified extension field of the rational numbers. In this paper we show how man...

1 One of the main drawbacks of the conventional reseeding architecture is the limited seed efficiency due to the variance in the number of specified bits per vector. This paper proposes a new LFSR reseeding architecture that essentially solves this problem, resulting in a significant compression ratio. The compression ratio is very close to the entropy in terms of #total bits / #specified bits....

In this paper, feedback with carry shift registers (FCSRs) are analyzed with main focus on the general case of FCSRs with arbitrary connection integer and on maximum-period FCSRs. Moreover, a keystream generator that employs the structure of the linear feedback shift register (LFSR)-based Geffegenerator is studied in connection with FCSRs as a special nonlinear combining generator. The consider...

We introduce a new kind of word-oriented linear feedback shift register called σ−LFSR which is constructed with the instructions of the modern processor and have fast software implementation. We offer an algorithm to search for good primitive σ−LFSR. In particular, we give two examples HHZ-1 and HHZ-2 and compare their efficiency and security with those of the LFSRs appearing in stream ciphers ...

A d-feedback-with-carry shift register (d-FCSR) is a finite state machine, similar to a linear feedback shift register, in which a small amount of memory and a delay (by d-clock cycles) is used in the feedback algorithm (see [4, 5]). The output sequences of these simple devices may be described using arithmetic in a ramified extension field of the rational numbers. In this paper we show how man...

Decim is a hardware oriented stream cipher submitted to the ECRYPT stream cipher project. The design of Decim is based on both a non linearly filtered LFSR and an irregular decimation mechanism called the ABSG. While the initial call for contributions required hardware-oriented stream ciphers to manage 80-bit secret keys and 64-bit public initialization, designers have been invited to demonstra...

In this paper, we present Decim, a stream cipher hardwareoriented selected for the phase 3 of the ECRYPT stream cipher project eSTREAM. As required by the initial call for hardware-oriented stream cipher contribution, Decim manages 80-bit secret keys and 64-bit public initialization vectors. The design of Decim combines two filtering mechanisms: a nonlinear Boolean filter over a LFSR, followed ...

Served as one of the most widely used wireless airlink interface, CDMA has been identified as a major technique for 3G wireless communications. The current IS-95 CDMA provides a near-satisfactory security solution to voice centric wireless communications, since generally each voice conversation only lasts a very short period of time. However, the security features provided by IS-95 CDMA are far...