Feedback with Carry Shift Registers (FCSRs) are a promising alternative to Linear Feedback Shift Registers (LFSRs) for the design of stream ciphers. The main difference between these two automata lies in the computation of the feedback. While LFSRs use simple bitwise addition, FCSRs use addition with carries. Hence, the transition function of an FCSR is non-linear, more precisely quadratic. Sin...

This paper introduces the differential cryptanalysis of additive stream ciphers, and develops its theoretical basis. The relationships between differential and other types of stream cipher analysis are presented. The conservation laws of patterns and of mutual information are derived. The cryptographic significance of pattern distribution of keystream sequences is shown. The cryptographic trans...

To produce ciphertexts, two modes of encryption are applied—block ciphers, which encrypt a fixed size block of plaintext at a time, and stream ciphers, which encrypt stream data, one or more bits at a time. As one of stream ciphers, the cipher feedback (CFB) mode is implemented by a block cipher via multiple stages, and in each stage, 1 bit or a number of bits of plaintext are encrypted at a ti...

We investigate the feasibility of using Graphics Processing Units (GPUs) for cryptographic processing by exploiting the ability for GPUs to simultaneously process large quantities of pixels to offload symmetric key encryption from the main processor. We demonstrate the use of GPUs for applying the key stream when using stream ciphers. We investigate the use of GPUs for block ciphers, discuss op...

This paper proposes the t-class of SOBER stream ciphers: t8, t16 and t32. t8, t16 and t32 offer 64-, 128and 256-bit key strength respectively. The t-class ciphers are based on the same principles as the original SOBER family: SOBER [17], SOBER-II [18], S16 and S32 [19], utilising the structure SOBER-II and S16 are based. The t-class ciphers are software stream ciphers designed for software impl...

Grain and Trivium are two hardware oriented synchronous stream ciphers proposed as the simplest candidates to the ECRYPT Stream Cipher Project, both dealing with 80-bit secret keys. In this paper we apply the linear sequential circuit approximation method to evaluate the strength of these stream ciphers against distinguishing attack. In this approximation method which was initially introduced b...

Salsa20 is a family of 256-bit stream ciphers designed in 2005 and submitted to eSTREAM, the ECRYPT Stream Cipher Project. Salsa20 has progressed to the third round of eSTREAM without any changes. The 20-round stream cipher Salsa20/20 is consistently faster than AES and is recommended by the designer for typical cryptographic applications. The reduced-round ciphers Salsa20/12 and Salsa20/8 are ...

The stream ciphers Salsa20 and Trivium are two of the finalists of the eSTREAM project which are in the final portfolio of new promising stream ciphers. In this paper we show that initialization and key-stream generation of these ciphers is slidable, i.e. one can find distinct (Key, IV) pairs that produce identical (or closely related) key-streams. There are 2 and more then 2 such pairs in Sals...