【作者】 陈春华；

【导师】 徐秋亮；

【作者基本信息】 山东大学 ， 计算机应用技术， 2007， 硕士

【摘要】 随着计算机通信网络的迅速发展，数字签名已在信息安全、身份认证、数据完整性、不可否认性等方面发挥了重要作用。指定接收者签名和代理签名是两种特殊形式的签名，在一个指定接收者签名体制中，只有指定的接收者才能验证签名的有效性；在一个代理签名体制中，一个原始签名人可以将他的签名权力委托给一个代理签名人，由代理签名人代表他去行使签名权。由于这两种签名体制的特殊性质，使得它们可以广泛地应用于电子商务等活动中。然而，目前已经提出的大多数指定接收者签名方案和代理签名方案在安全性和灵活性方面还不够理想，无法满足现实中对这两种体制的需要。因此，设计安全、灵活的签名方案具有重要的意义。本人在这几方面作了一些有益的尝试，分别提出了几个新的代理签名方案和指定接收者签名方案。本文的研究方法基于如下思想：安全性是衡量一个签名方案有没有实用价值的最重要的标准，一个没有安全性的签名方案将失去它存在的意义。因此在我们设计一些签名方案时把安全性放在了第一位，同时也考虑了方案的灵活性。在设计指定接收组签名方案时，在签名阶段是基于Schnorr签名的，因此它的安全性是建立在离散对数困难问题上的。而通过将签名的接收人与验证人设为一个群体，增加了在实际应用中的灵活性；我们在研究代理盲签名时发现，现有的很多代理盲签名方案在代理签名人和签名请求人会话阶段很容易受到恶意用户的攻击，文中通过身份认证等措施加强了代理盲签名的安全性，使之能更好地应用于实际环境中：多级代理签名有很重要的应用价值，可是我们发现研究者们对它的研究却很少，而现有的多级代理签名方案的安全等特性也不够理想。因此我们对多级代理签名的安全性重新做了界定，并提出了一强壮的多级代理签名方案，较之以前的签名方案的安全性有了很大的提高，同时也能使参与者灵活地掌握签名权的转移过程等。我们的研究由于主要是围绕安全性而展开的，因此有很重要的理论意义及很好的应用前景。本文研究内容与研究结果：1．对基本的数字签名体制及它们的安全性作了介绍和分析，并讨论了对数字签名体制的一些攻击方法；2．介绍指定证实者签名体制，介绍了一种构造指定证实者签名体制的方法，介绍了指定接收者签名体制，并新提出了两个指定接收者签名体制；3．介绍了几个常见的代理签名体制，分析了它们具有的安全性。对几种签名体制与代理签名体制的结合进行了研究，提出了在实际应用中对代理盲签名体制的一种攻击方法并给出了相应的抵御这种攻击的措施；结合指定接收者签名体制提出了两个指定接收者代理签名方案。最后提出了一个强多级代理签名方案，在这一方案中可以清晰地看出签名权的转移过程，使之能够很好地应用于实际。更多还原

【Abstract】 With the fast development of the intelcommunication and internet, digital signature plays an important role in information security, identity authentication, data integrality, undeniability and non-repudiation. Designated-receiver signature scheme and proxy signature scheme are two different types of special signatures. Designated -receiver signature scheme enables the receiver to verify the validity of signature, while proxy signature scheme allows a desinated person, called a proxy signer, to sign on behalf of an original signer. The property and charateristics of these two types of signature make them widely used in electronic business and other fields. However, most designated-receiver signature schemes and proxy signature schemes propoesed at present are not ideal in security and flexibility, which can not meet the need of reality. So it is important to design secure and flexible signature schemes. In this paper, some explorations have been made and several new designated-receiver signature schemes and proxy signature schemes are given respectively.The research approach in this paper is based on the thought that security is the most important standard to evaluate the practical value of a signature scheme and a signature scheme without security will lose the meaning on which it exists, so security should be placed on the first place and then the flexibility is taken into account, when some signature schemes are designed. When the assigned group-receiver signature scheme is designed, its security is established in the difficult question of separate logarithm, as its signature stage is based on Schnorr. The flexibility in application is strengthened through assigning the receiver and confirmer as a group; When we study the proxy blind signature we discovered that a lot of existing proxy blind signature schemes are easy to be attacked by the malicious user in the phase of conversation. In this paper several measures are proposed to strengthen the security of the proxy blind signature to enable it to be applied well in the actual environment; The multiple grade proxy signature is very important in application, but we discovered few researchers had done any research on it and the security and other characteristics of the existing multiple grade proxy signature schemes were not good enough. So in this paper the security of multiple grade proxy signature is redefined and a new strong multiple grade proxy signature is given, whose security is greatly promoted compared with the previous ones and which enable the involver in different grade have a good command of the transferred procedure of the signature. The studies in this paper are conducted focusing on the security of various schemes, therefore they are significant in theory and have good prospect in application.What have been studied in this paper and the main results that the author obtained are as follows:1. Some basic digital signature scheme and their security are analyzed and the possible attacks to digital signature schemes are discussed.2. Designated-verifier signature scheme and the way to construct the designated -verifier signature scheme are introduced. The designated-receiver signature schemes are discussed and two new the designated-receiver signature schemes are presented.3. Several common proxy signature schemes are introduced and their securities are analyzed. A couple of combination between signature schemes and proxy signature scheme are studied. A way of attacking to proxy blind signature scheme in reality is presented and the solution to the attacking problem is given at the same time. On the basis of the designated-receiver signature scheme, two new designated-receiver signature schemes are given in the paper. Finally a new multiple grade proxy signature scheme is given, in which the process of transfer from the signature verifers can be understood clearly and which can be easily applied in reality.更多还原