Information Processing System, Information Processing Method, and Information Processing Program

An information processing system that performs authentication using hash calculation, wherein

• said system is configured to:
• divide a plain text to be encrypted into n (n is a natural number) plain text blocks;
• set a first set value, which differs for each plain text, in the plain text to be encrypted;
• perform a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation result;
• output a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• perform a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th hash calculation result and encryption key to output an (i+1)th hash calculation result.

An information processing system that performs authentication using hash calculation, wherein

• said system is configured to:
• divide a plain text to be encrypted into n (n is a natural number) plain text blocks;
• set a first set value, which differs for each plain text, in the plain text to be encrypted;
• perform a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation result;
• output a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• perform a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th cipher text block and encryption key to output an (i+1)th hash calculation result.

The information processing system according to claim 21, comprising:

• block encryption mode use means for performing a hash calculation for a second calculation result obtained as the first calculation performed for the i-th hash calculation result and encryption key or i-th cipher block and encryption key to output an (i+1)th hash calculation result and selecting/setting an operand to be calculated by the first calculation at the time when the (i+1)th hash calculation result is output;
• one-way hash calculation means for performing a hash calculation in the block encryption mode use means;
• and
• parameter storage means for retaining the first set value which differs for each plain text and encryption key used for encryption processing.

An information processing method that performs authentication using hash calculation, comprising:

• dividing a plain text to be encrypted into n (n is a natural number) plain text blocks;
• setting a first set value, which differs for each plain text, in the plain text to be encrypted;
• performing a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation result;
• outputting a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• performing a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th hash calculation result and encryption key to output an (i+1)th hash calculation result.

An information processing method that performs authentication using hash calculation, comprising:

• dividing a plain text to be encrypted into n (n is a natural number) plain text blocks;
• setting a first set value, which differs for each plain text, in the plain text to be encrypted;
• performing a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation result;
• outputting a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• performing a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th cipher text block and encryption key to output an (i+1)th hash calculation result.

An information processing program that performs authentication using hash calculation, allowing a computer to execute processing of:

• dividing a plain text to be encrypted into n (n is a natural number) plain text blocks;
• setting a first set value, which differs for each plain text, in the plain text to be encrypted;
• performing a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation value;
• outputting a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• performing a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th hash calculation result and encryption key to output an (i+1)th hash calculation result.

An information processing program that performs authentication using hash calculation, allowing a computer to execute the processing of:

• dividing a plain text to be encrypted into n (n is a natural number) plain text blocks;
• setting a first set value, which differs for each plain text, in the plain text to be encrypted;
• performing a hash calculation for a first calculation result which is obtained as a result of a first calculation performed for the first set value and an encryption key to output a first hash calculation value;
• outputting a result which is obtained as a result of a second calculation performed for an i-th (i is a natural number satisfying i≦n) hash calculation result and an i-th plain text block as an encrypted i-th cipher text block;
• and
• performing a hash calculation for a second calculation result which is obtained as a result of the first calculation performed for the i-th cipher text block and encryption key to output an (i+1)th hash calculation result.