Cryptographic processing apparatus, cryptographic processing method, and computer program therefor

An information processing apparatus, comprising:

• means for storing key data necessary for cryptographic processing;
• a processor configured to execute various programs and to control starting and ending of the cryptographic processing;
• and
• an encryption processing apparatus configured to perform the cryptographic processing, the encryption processing apparatus including
• a first encryption processing section including first nonlinear transformation means for transforming first input information into first nonlinear transformed information, and first linear transformation means for transforming the first nonlinear transformed information into first linear transformed information;
• a second encryption processing section including second nonlinear transformation means for transforming second input information into second nonlinear transformed information, and second linear transformation means for transforming the second nonlinear transformed information into second linear transformed information;
• means for performing an exclusive-or operation based on the second linear transformed information and the first linear transformed information,
• wherein when the first nonlinear transformed information is expressed as a first sequence vector, the first linear transformed information is expressed as a second sequence vector, the second nonlinear transformed information is expressed as a third sequence vector, and the second linear transformed information is expressed as a fourth sequence vector, then (1) a first row vector chosen from a first inverse matrix of a first matrix that transforms the first sequence vector to the second sequence vector, and (2) a second row vector chosen from a second inverse matrix of a second matrix that transforms the third sequence vector to the fourth sequence vector, are linearly independent.

An information processing apparatus, comprising:

• a tangible memory unit that stores key data necessary for cryptographic processing;
• a processor configured to execute various programs and to control starting and ending of the cryptographic processing;
• and
• an decryption processing apparatus configured to perform the cryptographic processing, the decryption processing apparatus including
• a first decryption processing section, including a first nonlinear transformation unit configured to transform first input information to first nonlinear transformed information, and a first linear transformation unit configured to transform from said nonlinear transformed information to first linear transformed information;
• a second decryption processing section, including a second nonlinear transformation unit configured to transform second input information to second nonlinear transformed information, and a second linear transformation unit configured to transform from said nonlinear transformed information to second linear transformed information;
• and
• an exclusive-or section configured to perform an exclusive-or operation based on said second linear transformed information and said first linear transformed information,
• wherein when said first nonlinear transformed information is expressed as a first sequence vector, said first linear transformed information is expressed as a second sequence vector, said second nonlinear transformed information is expressed as a third sequence vector, and said second linear transformed information is expressed as a fourth sequence vector, a first row vector chosen from an inverse matrix of a first matrix, which indicates transformation from said first sequence vector to said second sequence vector, and a second row vector chosen from an inverse matrix of said second matrix, which indicates a transformation from said third sequence vector to said fourth sequence vector, are linearly independent.