LIGHTWEIGHT GROUP SIGNATURE SYSTEM AND SCHEMES WITH SHORT SIGNATURES

摘要

PURPOSE: A lightweight group signature system with short signatures and a method thereof are provided to improve operation efficiency in signature generation, signature verification, and revocation on smart terminals, while providing security characteristics at a similar level with group signature mechanisms which provide controllable linkability. CONSTITUTION: A key issuing unit(110) initially generates a group public key as a trusted subject and generates a master issuing key(mik), a master opening key(mok), and a master linking key(mlk) corresponding thereto. The key issuing unit performs an interactive protocol, when receiving a join request from a new user device(140), and issues a signature key to the user device. A key revocation identifying unit(120) identifies whether revocation is performed using the updated revocation list and the master opening key when the revocation identification request is received from the signature verifying unit(150) and then, returns the identified results to the signature verifying unit. The key revocation identifying unit uses the master opening key to output the verification information for identifying a signer when a valid signature is given. A signer identification proof evaluating unit(160) evaluates the validity of the signer identification proof generated from a signature control unit(100). [Reference numerals] (100) Control unit; (110) Key issuing unit; (120) Key revocation identifying unit; (130) Signature connecting unit; (140) User device; (150) Signature verifying unit; (160) Signer identification proof evaluating unit; (AA) Generating a group public key; (BB) Master issuing key; (CC) Master identifying key; (DD) Master connecting key; (EE) Confirming signature connection information; (FF) Requesting confirmation of signature connection; (GG) Confirming key revocation; (HH) Requesting confirmation of key revocation; (II) Requesting identification of a signer; (JJ) Issuing a signature key; (KK) Generating a signature; (LL) Generating signer identification proof; (MM) Confirming signer identification proof;