Signature verification apparatus capable of obtaining information required for a document recipient by using an apparatus's verification key alone

摘要

In apparatus for performing signature verification for an input document on which at least one digital signature is put by at least one signer assigned with a signer's user ID code, an inputting section inputs the signature document. A user ID identifying section identifies the signer's user ID code in the input document to produce an identified user ID code indicative of the signer's user ID code. A user verification key holding unit preliminarily holds user verification keys for respective user ID codes to produce an identified verification key which is one of the user verification keys that corresponds to the identified user ID code. A signature verifying unit verifies the digital signature in the input document by using the identified verification key to produce a signature verification result. A verification result indicator message creating unit creates the verification result indicator message indicative of the signature verification result. An apparatus's signature key holding section holds an apparatus's signature key assigned to said apparatus. A signing section signs at least the verification result indicator message by using the apparatus's signature key to produce a signed document. An outputting section outputs the signed document as an output document.