Patent ID: 8369516
Filing Date: 2013-02-05
Classification: H04L

Abstract:
1. A common key block encryption apparatus for computing 8-bit output data U −1 ∘f r from 8-bit input data U∘g r , where U is arbitrary 8-bit data, in a composite field GF(( . . . (2 β1 ) . . . ) βγ ) that satisfies βγ=2 by using 4-bit c r , 8-bit g r , 4-bit d r and 8-bit f r as fixed mask values selected with a random number r, and by using 8-bit R and R′ as random mask values, comprising: a masked U a 4-bit-to-4-bit transformation table circuit that is selected with a random number r, and configured to calculate 4-bit U a masked U