| 摘要 |
An efficient pseudo-random function and an efficient limited number of times authentication systemusing such a function are realized. A pseudo-random function calculating device comprises a key creating means and a pseudo-random function calculating means. The key creating means creates a public key made of a set of at least a first component and a second component as components constituting an element of a finite group and a secret key made of an integer and secretly saves the created secret key in a secret key memory section but makes the public key public. The pseudo-random function calculating means outputs the element of a finite group as function value of the pseudo-random function upon receiving an integer as input. The pseudo-random function calculating means outputs the product of multiplication of the first element of the value obtained by calculating the modular exponentiation, using the first component of the public key and the input integer respectively as base and exponent, and the second element of the value obtained by calculating the modular exponentiation, using the second component of the public key and the reciprocal of the sum of the secret key and the input integer in a finite field respectively as base and component. |
