一个门限代理签名方案的改进

1996年Mambo,Usuba和Okamoto提出了代理签名的概念，即在一个代理签名方案中，一个被指定的代理签名人可以代表原始签名人生成有效的代理签名，Mambo,Usuda和Okamoto指出代理签名方案应满足不可否认性，可验证性，不可伪造性，可区分性等性质并给出3种类型的代理签名：完全代理签名，部分代理签名和带有授权证书的代理签名，Sun,Lee和Hwang提出了一个门限代理签名方案（记为S－L－H方案），分析克服了由Zhang和Kim等提出的门限代理签名方案的缺点并给出了一个改进方案，这里指出S－L－H方案不能抵抗公钥替换攻击，并给出了一个改进的门限代理签名方案，进一步利用零知识的思想给出了抵抗公钥替换攻击的一般方法，改进后的方案除具有S－L－H方案的安全性外，还具有不可否认性，不使用安全信道，能抵抗公钥替换攻击和全谋攻击等特点。     

Convertible Proxy Signcryption Scheme

In 1996, Mambo et al introduced the concept of proxy signature. However, proxy signature can only provide the delegated authenticity and cannot provide confidentiality. Recently, Gamage et al and Chart and Wei proposed different proxy signcryption schemes respectively, which extended the concept of proxy signature.However, only the specified receiver can decrypt and verify the validity of proxy signcryption in their schemes.To protect the receiver‘ s benefit in case of a later dispute, Wu and Hsu proposed a convertible authenticated encryption scheme, which can enable the receiver to convert signature into an ordinary one that can be verified by anyone. Based on Wu and Hsu‘ s scheme and improved Kim‘ s scheme, we propose a convertible proxy signcryption scheme. The security of the proposed scheme is based on the intractability of reversing the one-way hash function and solving the discrete logarithm problem. The proposed scheme can satisfy all properties of strong proxy signature and withstand the public key substitution attack and does not use secure channel. In addition, the proposed scheme can be extended to convertible threshold proxy signcryption scheme.     

电子商务协议研究综述

电子商务协议是电子商务实施的技术基础.对电子商务协议研究进行综述,包括电子商务协议设计的原则(如安全性、匿名性、原子性、不可否认性和交易规模)以及对若干著名电子商务协议的描述和分析.     

一种基于PKI的安全电子邮件协议的设计

针对目前电子邮件的安全问题，提出了一种新型的基于PKI(Public Key Infrastructure)的安全电子邮件协议模型，并给出了具体的实现过程，该协议主要解决了邮件传输和接受过程中的身份认证、发送者和接受者的不可否认性、数据的完整性和保密性等问题。     

SIPmsign: a lightweight mobile signature service based on the Session Initiation Protocol

The development of mobile signatures could increase the spread and adoption of mobile services based on electronic signatures, such as mobile payments, mobile business transactions, and mobile government services. A Mobile Signature Service (MSS) means that a user in any of the scenarios mentioned can attach an electronic signature, anywhere, anytime, as with a handwritten signature with a device that is almost always on him or her. Several solutions have appeared, such as using the European Telecommunications Standard Institute MSS, the Mobile Signature Application Unit, and the Mobile Network Operator‐independent MSS. These solutions present two kinds of drawbacks. On the one hand, some of them require the service to be developed by all mobile network operators, whereas others are not based on efficient communications. In this paper, we present a new MSS named SIPmsign that solves these problems. Our proposal is based on the Session Initiation Protocol and defines how to exchange the information in a secure and more efficient way than previously. Thanks to Session Initiation Protocol, we provide the adoption of our proposal as a MSS for the new generation of mobile communications. In this paper, we also present the prototype we have developed as a proof of its feasibility as well as an evaluation of the performance of our solution. Copyright © 2012 John Wiley & Sons, Ltd.     

代理签名的现状与进展

首先描述了代理签名产生的背景、现状与进展。然后，介绍了代理签名的概念、要求、分类与述评，给出了几种典型的代理签名方案，并进行相应的分析与述评。最后，指出了目前代理签名方案存在的问题，并且对未来的研究方向进行了展望。     

Demonstrating the Elements of Information Security with Loss Scenarios

ABSTRACT

Nonrepudiation is currently legally supported by digital signatures. However, problems with digital signatures have been analyzed in several papers, which consequently create doubts for the signatures' ability to support nonrepudiation. The addressing of weaknesses of digital signatures through the use of biometrics has also been considered. The scope of this paper is the identification of the most suitable biometric technology to be used for nonrepudiation purposes.     

具有已知代理人的不可否认门限代理签密方案

1996年,Mambo等人提出了代理签名概念.但是,代理签名仅能提供授权的认证而不能提供保密性.Chan和Wei提出一个门限代理签密方案(记为Chan-Wei方案),扩展了代理签名的概念.指出他们的方案不满足强不可伪造性、强不可否认性和强识别性.基于Chan-Wei方案,提出一个能够克服Chan-Wei方案缺点的不可否认门限代理签密方案.给出方案的完备性证明和安全性分析.此外,与Chan-Wei方案相比,所提出的方案能够确切地发现哪些代理人提供假子密钥或篡改子密钥.     

An Efficient Quantum Mechanism Based Fair Non-Repudiation Protocol

In this paper, an efficient quantum public key signature based fair non-repudiation message exchanging protocol is proposed. This protocol could guarantee fairness which means both the receiver and the sender could get the evidences of each other at the end of message transmission. Compared with the traditional nonrepudiation protocols, this protocol provides higher security because of the superiority of quantum cryptography as well as enhances the running time efficiency and reliability since it avoids the involvement of TTP （Trusted third party）.