Patent ID: 7533269

Claim:
An information processor for supporting an exchange of a digital-signed digital document, the processor comprising: communication means connected to a network; and processing means for, when the communication means receives a sign request including a first digital document from a first computer on the network, canonicalizing the first digital document by a method of implementing a canonicalization process, calculating a digest value of the canonicalized first digital document, and causing the communication means to output the digest value to the first computer, wherein the processing means is further adapted to perform the steps of: when the communication means receives a sign request including a second digital document from a second computer on the network, canonicalizing the second digital document by the same method of implementing the canonicalization process, calculating a digest value of the canonicalized second digital document, and causing the communication means to output the digest value to the second computer, and when the communication means receives from one of the first and second computers on the network a validation request including a public key for validating a digital document with a digital sign and the digital document with the digital sign has been received from the other one of the first and second computers, canonicalizing the digital document by the same method of implementing the canonicalization process, calculating a digest value of the canonicalized digital document, comparing a value obtained by decrypting the digital sign with the public key and the calculated digest value, and causing the communication means output the result of the comparison to the computer which sent the validation request.