Patent ID: 7760870

Claim:
A data transformation apparatus having a data processing unit performing at least one of encryption of data and decryption of data based on key data inputted thereto, wherein the data processing unit comprises: a subfield transformation unit configured to transform input data inputted thereto by an inverse element circuit using a subfield of a field by treating the input data as an element of the field, and output the transformed data; and an affine transformation unit for vector space GF(2) n on GF(2) configured to transform data on GF(2 n ) inputted thereto into data on GF(2) n by treating the data on GF(2 n ) as an element of GF(2) n , the affine transformation unit being connected in series with the subfield transformation unit, wherein the affine transformation unit is implemented using at least one of a computer processor and a logical operation circuit.