An Integrated Blind and Weakly Undeniable Multisignature Scheme and a Multiauthority Internet Bidding System

• Main Authors: Chun-Nan Huang, 黃俊南
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/8vks43

碩士 === 逢甲大學 === 電子工程所 === 90 === Abstract Digital signature is the most important service that contemporary cryptography provides. It is the foundation of mutual trust in the Internet; also, it is the key technique of putting e-Government and e-commerce into practice successfully and generally. Electronic signature is extensively applicable in various surroundings and ways. Accordingly, many different types of signatures have been developed to apply to varied application surroundings and ways during the past two decades. However, ways and structures of Internet communication become more and more complicated. Therefore, there are more and more cryptographic services each of which needs the aid of several different types of signatures. For example, in a robust electronic payment system, blind signature, undeniable signature, and multisignature should be all indispensable. In this situation, if independently different signature schemes are used, it may cause extremely enormous computation cost, for the parameters and modulus used in different schemes could be quite different. In addition, it may lower the practical efficiency of the system, and make people who are not familiar with cryptography feel inconvenient and awed. Accordingly, the problem of designing an integrated system that will simultaneously provide services of several different types of signatures is the very significant research issue to contemporary cryptography, and needed to solve it as soon as possible. Unfortunately, there has been no such a scheme proposed to date. In this thesis, we propose the first concept of integrated signature and concentrate ourself on the design of an integrated signature scheme that has the following engaging properties: (1) It is a distributed RSA type. (2) It is both a blind signature and a weakly undeniable signature. (3) The modulus used by each participant cosigner is identical. (4) It is identical in form to a standard RSA signature. (5) The length of the signature is independent of the number of participant cosigners. (6) The unforgeability of the scheme is equivalent to an ordinary RSA signature scheme. Being a multisignature, the power and responsibility of the signer can be distributedly shared by a set of cosigners. Being blind and unlinkable, the privacy as well as anonymity of the signature requester is protected. Further, being weakly undeniable, it protects the signers and gives them more control over the verification of the signature. Accordingly, the suggested scheme is more suitable for many important cryptographic services, such as secure electronic voting service, electronic payment service and other electronic commerce service etc, than an ordinary signature scheme. Therefore, based upon the suggested weakly undeniable and blind multisignature scheme, we also develop a secure multiauthority Internet bidding system in order to prevent possible cheating from a single authority system.