| 摘要 |
Realized are an efficient pseudo-random function and an efficient number-limited anonymous authentication system using that function. A pseudo-random function calculation device comprises key creating means and pseudo-random function calculating means. The key creating means creates a public key made of a group having first and second elements as components composing the elements of a finite group, and a secret key made of an integer, and the secret key is secretly stored in a secret key storage unit whereas the public key is laid open. The pseudo-random function calculating means outputs, when an integer is inputted, elements of finite groups as the function values of the pseudo-random function. At this time, the output is the product of a first element having a value obtained by calculating a power-residue with the first element of the public key as a base and with the inputted integer as an exponent, and a second element obtained by calculating a power-residue with a second element of the public key as a base and with a reciprocal of a finite of a sum of the secret key and the inputted integer as an exponent. |
