26 research outputs found
MV3: A new word based stream cipher using rapid mixing and revolving buffers
MV3 is a new word based stream cipher for encrypting long streams of data. A
direct adaptation of a byte based cipher such as RC4 into a 32- or 64-bit word
version will obviously need vast amounts of memory. This scaling issue
necessitates a look for new components and principles, as well as mathematical
analysis to justify their use. Our approach, like RC4's, is based on rapidly
mixing random walks on directed graphs (that is, walks which reach a random
state quickly, from any starting point). We begin with some well understood
walks, and then introduce nonlinearity in their steps in order to improve
security and show long term statistical correlations are negligible. To
minimize the short term correlations, as well as to deter attacks using
equations involving successive outputs, we provide a method for sequencing the
outputs derived from the walk using three revolving buffers. The cipher is fast
-- it runs at a speed of less than 5 cycles per byte on a Pentium IV processor.
A word based cipher needs to output more bits per step, which exposes more
correlations for attacks. Moreover we seek simplicity of construction and
transparent analysis. To meet these requirements, we use a larger state and
claim security corresponding to only a fraction of it. Our design is for an
adequately secure word-based cipher; our very preliminary estimate puts the
security close to exhaustive search for keys of size < 256 bits.Comment: 27 pages, shortened version will appear in "Topics in Cryptology -
CT-RSA 2007
Towards a spectral approach for the design of self-synchronizing stream ciphers
International audienceThis paper addresses the problem of characterizing the func- tions that can be used in the design of self-synchronizing stream ciphers. We propose a general framework based on a spectral characterization through correlation matrices or equivalently through Walsh matrices. Two modes of self-synchronization are discussed: the finite time one and the statistical one
A Novel Design Method of Stream Ciphers Based on Table-Element Permutation
In this paper, a new stream ciphers design method (named TEP) is proposed to base on the table-element nonlinear permutation. A number of words are generated by n-LFSRs(linear feedback shift register) input to a table. In the table, every word is dealt with by the nonlinear transforms and the several words are combined with nonlinear function to produce keystream words. The algorithm is simplicity and the secret key is generated rapidly. The result of many simulation experiments show that the keystream by TEP method generating can meet DIEHARD statistics tests. The approach is efficient to design stream ciphers
Statistical Properties of Multiplication mod
In this paper, we investigate some statistical properties of multiplication mod for cryptographic use.
For this purpose, we introduce a family of T-functions similar to modular multiplication, which we call
M-functions as vectorial Boolean functions. At first, we determine the joint probability distribution of
arbitrary number of the output of an M-function component bits. Then, we obtain the probability distribution
of the component Boolean functions of combination of a linear transformation with an M-function. After that,
using a new measure for computing the imbalance of maps, we show that the restriction of the output of an
M-function to its upper bits is asymptotically balanced
New construction of single-cycle T-function families
The single cycle T-function is a particular permutation function with complex algebraic structures, maximum period and efficient implementation in software and hardware. In this paper, on the basis of existing methods, we present a new construction using a class of single cycle T-functions meeting certain conditions to construct a family of new single cycle T-functions, and we also give the numeration lower bound for the newly constructed single cycle T- functions
New construction of single cycle T-function families
The single cycle T-function is a particular permutation function with complex algebraic structures, maximum period and efficient implementation in software and hardware. In this paper, on the basis of existing methods, by using a class of single cycle T-functions that satisfy some certain conditions, we first present a new construction of single cycle T-function families. Unlike the previous approaches, this method can construct multiple single cycle T-functions at once. Then the mathematical proof of the feasibility is given. Next the numeration for the newly constructed single cycle T-functions is also investigated. Finally, this paper is end up with a discussion of the properties which these newly constructed functions preserve, such as linear complexity and stability (k-error complexity), as well as a comparison with previous construction methods
Statistical Properties of the Square Map Modulo a Power of Two
The square map is one of the functions that is used in cryptography. For instance, the square map is used in Rabin encryption scheme, block cipher RC6 and stream cipher Rabbit, in different forms. In this paper we study a special case of the square map, namely the square function modulo a power of two. We obtain probability distribution of the output of this map as a vectorial Boolean function. We find probability distribution of the component Boolean functions of this map. We present the joint probability distribution of the component Boolean functions of this function. We introduce a new function which is similar to the function that is used in Rabbit cipher and we compute the probability distribution of the component Boolean functions of this new map