Keywords : cipher
Engineering and Technology Journal,
2015, Volume 33, Issue 3, Pages 427-442
A stream cipher is a symmetric cipher which operates with a time-varying transformation onIndividual plaintext digits. By contrast, block ciphers operate with a fixed transformation on large blocks of plaintext digits. Where in the operation of Key generator is using the LFSR to generate random keys where the shift register is controlled by an external clock. At each time unit, each digit is shifted one stage to the right. The content of the rightmost stage is output. The new content of the leftmost stage is the feedback bit, st+L.
this paper presents design and implementation system of keys generator with nonlinear random of output keys and large moment bits, this system consists of three part from registers , logical circuits and search algorithm using AI work in parallel time to find the result, the LFSRs in registers part (left and right of system)can generate huge moment of bits and pass in randomness test, those bits by the logical circuit and search algorithm convert from linear to nonlinear to get more difficult in break secret keys, finally, the keys can be used in stream cipher or in block cipher methods.