Patent ID: 8370633

Claim:
An information processing apparatus comprising: a signature generating section that generates an electronic signature σ by using a signature key KS associated with a verification key KV; and a substitute-key generating section that generates, with respect to an electronic document m to which the electronic signature σ is attached by the signature generation section, a substitute verification key KV', where KV′≠KV, that is capable of verifying a validity of the electronic signature σ and a substitute signature key KS′, where KS′≠KS, associated with the substitute verification key KV′; wherein, in a predetermined case, the verification key KV and the signature key KS are updated to the substitute verification key KV′ and the substitute signature key KS′ wherein when the signature generating section generates N electronic signatures σ j , where j=1, . . . , N, and N≧2, with respect to N electronic documents m j , the substitute-key generating section generates the substitute verification key KV′ that is capable of verifying the validity of the electronic signatures with respect to M combinations, where 2≦M≦N, of the N combinations m j and σ j of the electronic documents and the electronic signatures and the substitute signature key KS′ associated with the substitute verification key KV′, wherein the information processing apparatus includes a processor and memory.