A Digital Signature and Message Hash Value Restoration and Signature Verification Method

Abstract

Aiming at a digital signature algorithm not supporting that a message hash value, when signature operation is carried out, is recovered from a signature value, the invention provides a digital signature and message hash value recovery method. When signature operation is carried out, a cryptographic module takes the message hash value as filling or additional data, and fills or adds the message hash value into the signature value after signature operation of the message hash value is carried out by using a private key, such that a final signature value is formed; when a digital signature application program requests for recovering the message hash value, when the digital signature operation is carried out, from the signature value by using a public key of a signer, the cryptographic module obtains or separates the filled or added message hash value after signature operation from the signature value; then, the signature value after cryptographic operation by using the private key of the signer is subjected to signature verification by using the obtained message hash value and the public key of the signer; if verification is passed, the message hash value obtained or separated from the signature value is used as the recovered message hash value and returned; and otherwise, a fixed value or a random value is used as the recovered message hash value and returned.

Description

technical field [0001] The invention belongs to the technical field of cryptography, in particular to a method for recovering digital signatures and message hash values. Background technique [0002] There are currently two types of digital signature schemes. [0003] A kind of digital signature, using the signer's private key to sign the message (message) hash value (hash value) (referred to as the message hash value) to perform encrypted cryptographic operations, that is, signature operations, and the result of the operation is used as a message signature The signature value (signature value); in digital signature verification, use the signer's public key to perform decryption cryptographic operations on the signature value, decrypt and obtain the hash value of the message during the signature operation, and then use the hash value of the message to verify the signature Perform a comparison (direct comparison of the hash values), if the two are the same, the digital signa...

AI Technical Summary

Problems solved by technology

However, there will be such a problem in practical applications: the digital signature application program uses the method of recovering the hash value of the message during the signature operation from the signature value to perform signature verification, while the digital signature application program calls the cryptographic module to digitally sign the message. The digital signature algorithm does not support the recovery of the hash value of the message from the signature value, so the digital signature application program will not be able to call the interface function of the cryptographic module to recover the hash value of the message from the signature value, and the signature value to be verified The hash value of the message when the signature operation is restored to complete the digital signature verification