Block cipher apparatus using auxiliary transformation
AssigneesMitsubishi Denki Kabushiki Kaisha, Nippon Telegraph and Telephone Corporation
InventorsMitsuru Matsui, Toshio Tokita, Junko Nakajima, Masayuki Kanda, Shiho Moriai, Kazumaro Aoki
Life of this patent
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Abstract
It is desired to share one circuit by an encryption unit 200 and a decryption unit 500. A normal data transformation unit (FL) 251 and an inverse data transformation unit (FL−1) 273 are located at point symmetry on a non-linear data transformation unit 220, and a normal data transformation unit (FL) 253 and an inverse data transformation unit (FL−1) 271 are located at point symmetry on the non-linear data transformation unit 220. Therefore, the encryption unit 200 and the decryption unit 500 can be configured using the same circuits.
Claims4
A data transformation apparatus having a data processing unit for inputting key data and performing at least one of encryption of data and decryption of data, wherein the data processing unit comprises:
- a subfield transformation unit for inputting data to be transformed, assuming the data as an element of a field, transforming the data by an inverse element circuit using a subfield of the field, and outputting transformed data;
- and
- an affine transformation unit for vector space GF(2)n on GF(2), provided at at least one of a former round and a latter round of the subfield transformation unit, for assuming data on GF(2)n to be transformed as an element of GF(2)n which corresponds naturally.
A data transformation method for executing a data processing process for inputting key data and performing at least one of encryption of data and decryption of data, wherein the data processing process comprises:
- a subfield transformation process for inputting data to be transformed, assuming the data as an element of a field, transforming the data by an inverse element circuit using a subfield of the field, and outputting transformed data;
- and
- an affine transformation process for vector space GF(2)n on GF(2), provided at at least one of a former round and a latter round of the subfield transformation unit for assuming data on GF(2)n to be transformed as an element of GF(2)n which corresponds naturally.
Dependencies are inferred from the claim text.