Encryption processing method, apparatus, and computer program utilizing different types of S-boxes

An encryption processing method of performing encryption processing in an encryption processing apparatus, the method comprising:

• an encryption processing step of performing, in an encryption processing part, data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a
• wherein the encryption processing step is configured to include different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function;
• wherein the encryption processing step is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

A non-transitory computer-readable medium encoded with a computer program that causes an encryption processing apparatus to perform encryption processing, the encryption processing comprising:

• an encryption processing step of performing, in an encryption processing part, data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the encryption processing step is a step of performing data transformation processing using different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the encryption processing step is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

A decryption processing apparatus comprising:

• a decryption processor that performs data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the decryption processor is configured to include different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the decryption processor is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

A decryption processing method of performing decryption processing in a decryption processing apparatus, the method comprising:

• a decryption processing step of performing, in an encryption processing part, data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the decryption processing step is a step of performing data transformation processing using different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the decryption processing step is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

A non-transitory computer-readable medium encoded with a computer program that causes a decryption processing apparatus to perform decryption processing, the decryption processing comprising:

• a decryption processing step of performing, in an encryption processing part, data transformation processing using an F-function a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the decryption processing step is a step of performing data transformation processing using different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the decryption processing step is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

An information processing apparatus comprising:

• at least one processor,
• at least one memory device storing instructions that cause the apparatus to encrypt data by performing data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the apparatus is configured to include different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the apparatus is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.

An information processing apparatus comprising:

• at least one processor,
• at least one memory device storing instructions that cause the apparatus to decrypt data by performing data transformation processing using a plurality of F-functions including S-boxes as a round function on individual data lines obtained by dividing input data by a number greater than or equal to three,
• wherein the apparatus is configured to include different types of S-boxes in the plurality of F-functions that have the same input data line and output data line and that are vertically adjacent to one another, the different types of S-boxes in the plurality of F-functions having the same bit configuration, the data input to each of the plurality of F-functions being the result of an exclusive-OR operation on the data input to a previous F-function, and
• wherein the apparatus is further configured to perform non-linear transformation processing, using at least two different s-bit input/output types of S-boxes, wherein the at least two different types of S-boxes are:
• (1) type 1:
• an S-box using an inverse map:
• Y=X−1 or a power function Y=Xq over an extension field GF(2s);
• (2) type 2:
• an S-box generated by combining a plurality of small t-bit S-boxes, where t<s;
• and
• (3) type 3:
• an S-box selected at random.