Unlinkable Concurrent Signcryption Scheme with Innocent Signer Protection

• Main Authors: Yen-Shih Lee, 李彥賜
• Other Authors: 黃心嘉
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/96808089771290769608

碩士 === 淡江大學 === 資訊工程學系資訊網路與通訊碩士班 === 102 === Concurrent signature schemes can be classified into two classes: linkable concurrent signatures and unlinkable concurrent signatures. To protect the transaction privacy, the unlinkable concurrent signatures are better than the linkable ones. However, the unlinkable concurrent signatures cannot used as innocence clarification since no link between the exchanged message and concurrent signature pairs can be used to prove their concurrent signatures have legal and valid usages. To prevent this flaw, the concept of designated verifier commitment is proposed first. By adopting our designated verifier commitment, an unlinkable concurrent signcryption scheme with innocent signer protection is proposed to provide privacy protection and innocence classification at the same time. Moreover, our scheme efficiently provides the message confidentiality for complete privacy protection. Besides, a cheating attack is proposed to show that Zhang and Xu’s scheme is unfair, since the initial signer can obtain a concurrent signature on messages without the matching signer’s agreement while the matching signer cannot obtain his/her desired concurrent signature.