【作者】 杜秋双；

【导师】 王国军；

【作者基本信息】 中南大学 ， 计算机科学与技术， 2011， 硕士

【摘要】 在信息技术朝着高性能、多样化、普适化和智能化等主要方向持续发展的今天,因特网上的多媒体业务变得多种多样。组播通信能够很好地解决多个用户的接收问题,其实质就是针对个性化需求,高效组织计算资源,构造可以适应用户需求的安全网络应用环境。随着组播通信开始从理论研究走向实际应用,其安全问题越来越突出。特别是多权限组播通信中的安全问题,比传统(单一权限)组播通信中的安全问题更难解决。本论文首先介绍了组播通信技术中已有的群组密钥管理协议,并针对这些协议中的密钥树都是二叉树、不利于系统扩展的局限,提出了基于单向函数和多叉树的群组密钥管理协议(One-Way Function and Multiway Tree-Based Group Key Management Protocol,简称OMGM)。该协议将多叉树作为密钥图的构造基础,有效降低了密钥树高度,进而减少了群组管理者和用户的密钥存储、密钥更新和网络开销。同时,该协议采用随机数辅助密钥更新,可以大大降低因广播更新密钥而引起的网络带宽消耗。另外,本论文在基于属性加密的基础上提出了一种适用于多权限组播通信的安全加密方案(A Scalable Encryption Scheme for Multi-Privileged Group Communications,简称EMGC)。该方案采用属性标记数据流,同时将合法用户信息融入密文,这样通过属性和ID的双重限制来保证组播通信的前向和后向安全性。针对不同的应用环境,本论文给出了两种加密方法：方法一适用于用户在不同服务组之间转移频率较高的情况,并且公钥长度较小；方法二对公钥和密文长度进行了折中,而且保证了在组播消息过程中,群组管理者和用户具有较少的计算开销。总之,本论文解决了多权限组播通信中的若干安全问题,包括密钥管理协议和加密方案的设计。从而保证了组播通信中的安全性,解决了密钥的分发和更新问题,减少了群组管理者和成员的计算、存储开销,降低了占用的网络带宽等。这些研究成果将应用到实际中去,改变多权限组播通信“研究多、应用少”的现状。更多还原

【Abstract】 With the rapid development of network technologies, more and more multimedia applications and services are provided over the Internet. Group communications were proposed to adapt the demand for individuation, organizing computing resources efficiently, and constructing secure network applications which could meet users’needs. As group communications began to be used in practical application other than theory, security issues in them are increasingly prominent. Especially for multi-privileged group communications, they are more difficult to solve than those in traditional group communications.This thesis first introduces some existing group key management schemes. As the key graphs in these schemes are binary trees, which are not good for scalability, we propose a one-way function and multiway tree-based group key management protocol (OMGM). It is based on multiway tree, which could reduce the height of key tree effectively. Thereby the scheme can reduce the key storage overhead of server and users. What’s more, it uses a random number to support key updating, which can greatly reduce the overhead of network bandwidth caused by broadcasting new keys during key updating.In addition, this thesis also proposes a scalable encryption scheme for multi-privileged group communications (EMGC) based on Attribute-Based Encryption (ABE). It uses attributes to describe data streams in group communications, and ciphertexts are labeled with an access control structure and the set of legal users’IDs. The forward and backward secrecy are ensured by the attributes and users’ID set. Moreover, based on the features of different multi-privileged group communication systems, it proposes two constructions for EMGC scheme. Construction 1 can benefit users’switching and has a small size of public key, while the other makes a tradeoff between the size of public key and ciphertext, and also reduces the computational overhead of server and users.This thesis studies and solves some security issues in multi-privileged group communications, including the designing of group key management protocol and encryption scheme. They can be used to ensure the security in multi-privileged group communications, achieve key distribution and updating, reduce the computational and storage overhead of servers and users, reduce the overhead of network bandwidth, and so on. These achievements can be well applied to applications, and change the "research more, while applied less" status of multi-privileged group communications.更多还原