Author : Surya Rajan and Rincy Merin Varkey

Large integer multiplication is one of the most resource and time consuming operation in cryptographic applications. So, efficiency in multiplication is very important. In this paper, architecture for high performance Welch-Gong(WG) cipher is explained. WG cipher is synchronous stream cipher based on WG transformations. These ciphers encrypt a plaintext or decrypt a cipher-text by adding the plain-text or cipher-text bit by bit with the generated key stream bits. The performance of the WG Cipher is increased by using high speed Karatsuba Multiplier. This multiplier works based on Karatsuba Algorithm which reduces the multiplication of two n-digit numbers to at most nlog23≈n 1.585 single-digit multiplications in general. It is therefore faster than other algorithms. The WG cipher has been designed to produce key-stream with guaranteed randomness properties and is resistant to Time/Memory/Data trade-off attacks, algebraic attacks and correlation attacks. The architecture is synthesized using Xilinx ISE Design Suite14.2 and simulated using Xilinx ISim.

Keywords: Welch-Gong transformation, Galois Field, Optimal Normal Basis (ONB), Karatsuba Algorithm, Stream Ciphers.

Article published in International Journal of Current Engineering and Technology, Vol.5, No.6 (Dec-2015)