Abstract

Cipher is an algorithm for transforming the message. Stream ciphers are light weight symmetric key cryptosystems. These ciphers encrypt a plain-text or decrypt a cipher-text by adding the plain-text or cipher-text bit by bit with the generated keystream bits. Welch-Gong (WG) stream cipher is a cryptographically secure stream cipher. The keystream necessary for generating the WG stream cipher is generated using Welch-Gong keystream generator. The architecture is designed in such a way to reduce the computational complexity by reducing the number of multipliers. The WG design uses the properties of the trace function by using type II optimal normal basis (ONB) representation to optimize the hardware cost in the WG transformation. In-order to reduce the complexity, some necessary signals needed to generate the initial feedback signal is eliminated and further recovered through a new module called Serialized Key Initialization Module (SKIM). The area overhead can be reduced and the performance can be increased by replacing the finite field multiplier used in the WG transformation by high speed Vedic multiplier. The architecture is synthesized using Xilinx ISE Design Suite13.2 and simulated using Xilinx ISim.

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