Patent ID: 8295479

Claim:
A data conversion function processor for performing a process of a data conversion function in a non-uniform MISTY structure which includes an n-bit data path and an m (m<n)-bit data path and to which the two data paths are connected by zero-extend conversion or truncate conversion in each stage, comprising: a zero-extend conversion unit provided on a route connecting between the two data paths, to convert m bits branched and inputted from the data path of the m bits to n bits by zero-extend conversion; a first exclusive OR calculator provided on a route connecting between the two data paths, to calculate an exclusive OR of n bits outputted from the zero-extend conversion unit and an n-bit round key KIij 2 ; a second exclusive OR calculator to calculate an exclusive OR of lower-order m bits of the round key KIij 2 and an m-bit round key KIij 1 ; and a third exclusive OR calculator provided on the m-bit data path, to calculate an exclusive OR of m bits outputted from the second exclusive OR calculator and m bits inputted from the m-bit data path.