Patent ID: 8356182
Filing Date: 2013-01-15
Classification: H04L

Abstract:
1. An electronic signature system for verifying the legitimacy of a target message with an electronic signature generated for the target message, comprising: a key generating apparatus for generating a first public key and a first secret key according to a key generating algorithm of an electronic signature scheme which satisfies an unforgeability, using a predetermined security parameter as an input, and generating a second public key and a second secret key according to a GenCam algorithm of a chameleon commitment scheme, using the predetermined security parameter as an input; a signature apparatus for generating a commitment and a first random number according to a Com algorithm of said chameleon commitment scheme, using said second public key generated by said key generating apparatus and an arbitrary message as inputs, generating a first signature according to a signature algorithm of the electronic signature scheme which satisfies the unforgeability, using said first secret key generated by said key generating apparatus as an input, generating a second random number according to a Cam algorithm of said chameleon commitment scheme, using a signature-affixed message which comprises said target message with said first signature affixed thereto, said second public key, said second secret key, said commitment, and said first random number as inputs, and generating an electronic signature for said target message, which includes said first signature and said second random number; and a verification apparatus for generating a commitment according to a ComVer algorithm of said chameleon commitment scheme, using the signature-affixed message which comprises said target message with said first signature affixed thereto that is included in said electronic signature, said second random number included in said electronic signature, and said second public key as inputs, verifying the legitimacy of the first signature according to a verification algorithm of the electronic signature scheme which satisfies the unforgeability, using the generated commitment, said first signature, and said first public key as inputs, and regarding a verified result as a verified result of said electronic signature.