795 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
A fast and light stream cipher for smartphones
We present a stream cipher based on a chaotic dynamical system. Using a
chaotic trajectory sampled under certain rules in order to avoid any attempt to
reconstruct the original one, we create a binary pseudo-random keystream that
can only be exactly reproduced by someone that has fully knowledge of the
communication system parameters formed by a transmitter and a receiver and
sharing the same initial conditions. The plaintext is XORed with the keystream
creating the ciphertext, the encrypted message. This keystream passes the NISTs
randomness test and has been implemented in a videoconference App for
smartphones, in order to show the fast and light nature of the proposed
encryption system
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