Patent ID: 8121290

Claim:
A pseudo-random function calculating device comprising: key creating means for creating 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, secretly saving the generated secret key in a memory device and opening the public key; and pseudo-random function calculating means for outputting the element of a finite group as function value of the pseudo-random function upon receiving an integer as input, wherein the pseudo-random function calculating means outputs as the element of a finite group 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 exponent.