Patent ID: 6910130

Claim:
A center computer in a digital signature system, comprising: first generating means for generating a signing-key for a signer; second generating means for generating a verification-key for a verifier; a first output device outputting the signing-key generated by the first generating means; and a second output device outputting the verification-key generated by the second generating means, wherein: the first generating means comprises means for generating a first multivariate function, and means for generating a second multivariate function obtained by substituting the signer's identification code into a first variable of the first multivariate function; the first output device outputs the second multivariate function as the signing-key for the signer; the second generating means comprises means for generating a random number, a third multivariate function obtained by substituting the random number to a second variable of the first multivariate function; and the second output device outputs the random number and the third multivariate function as the verification-key for the verifier.