一类基于数字签名的密钥认证方案

 本文基于文献[1]中提出的数字签名方案,产生一种新的密钥认证方案,同时给出基于一般的ElGamal数字签名方案的密钥认证方案.在这种新的密钥认证方案中,认证信息由用户独立产生,不通过TC或KAC,认证过程没有应用Hash函数.     

基于Diffie—Hellman的一次性口令认证方案

针对目前一次性口令的不足,借鉴质询/响应方案的思想设计了一种基于Diffie-Hellman的一次性口令认证方案.与传统方案相比,该方案不仅能够提供通信双方的相互认证,而且能够抵抗重放攻击、离线口令猜测攻击和假冒攻击,极大地增强了应用系统的安全性.     

报文摘要算法MD5的分析与改进

MD5算法在数据加密方面有着广泛的应用,但是它无法抵御查字典攻击和差分等攻击。为此本文介绍了报文摘要算法MD5和Base64算法,以及在两种算法的基础上提出了MD5的改进算法,以应对以上被攻击的缺陷。     

CDMA2000下载业务系统中Download协议监测技术的研究与实现

增值业务的产生,丰富了通信网络,同时也增加了网络负荷.为保证通信质量,对增值业务关键接口进行监测的研究显得尤为重要.以CDMA2000网络作为承载网络,以增值业务网络中的下载业务系统作为切入点,对该系统与WAP网关相连接口下的Download协议进行监测研究;通过构造合理的哈希函数优化了CDR（calling de-tail record）合成处理速度.将此方法推广至增值业务中的其他关键接口,通过现网数据测试,运行效果良好.     

A localized certificate revocation scheme for mobile ad hoc networks

The issue of certificate revocation in mobile ad hoc networks (MANETs) where there are no on-line access to trusted authorities, is a challenging problem. In wired network environments, when certificates are to be revoked, certificate authorities (CAs) add the information regarding the certificates in question to certificate revocation lists (CRLs) and post the CRLs on accessible repositories or distribute them to relevant entities. In purely ad hoc networks, there are typically no access to centralized repositories or trusted authorities; therefore the conventional method of certificate revocation is not applicable.In this paper, we present a decentralized certificate revocation scheme that allows the nodes within a MANET to revoke the certificates of malicious entities. The scheme is fully contained and it does not rely on inputs from centralized or external entities.     

基于最大秩距离码的Niederreiter公钥密码体制的改进

为提高基于最大秩距离码的Niederreiter公钥密码体制的性能,对该体制进行了修改.利用双公钥及哈希函数来改进基于最大秩距离码的Niederreiter公钥密码体制,增加该体制的攻击复杂度;利用目前攻击Niederreiter公钥密码体制的方法对其进行安全性测试和分析,证明了该体制的安全性;对公开密钥的校验矩阵进行初等变换,从而减少体制的公开密钥量,提高了体制的纠错能力.     

一种新型的具有可变散列输出的Hash函数

给出一种具有可变散列输出的Hash算法.该算法可以把任意长的消息散列成160,192,224或256比特的消息摘要.算法采用了分段式非线性码字扩展方案,通过整数帐篷映射拉伸与折叠的非线性本质实现消息的非线性扩展,将整数帐篷映射与传统的逻辑函数相结合,作为压缩函数迭代过程的非线性部件,具有较为理想的混淆与扩散特性.压缩函数内部采用了并行迭代结构,有利于软硬件高速并行实现.     

基于Δ调制反馈离散时间系统的Hash函数研究

Δ调制反馈离散时间系统在一定的参数范围内出现混沌运动,其产生的混沌序列具有良好的伪随机性、遍历性和初值敏感性。文中基于该系统建立了一个带秘密密钥的Hash函数算法,算法以迭代初始点作为秘密密钥。实验表明:该方法简单,具有良好的单向散列性能,并能满足一定的安全性要求。     

集成加密方案ECIES的设计与验证

椭圆曲线密码（ECC,elliptic curve cryptograph）是密码学的重要分支之一,它可以用来加密数据,进行数字签名或者在安全通信的开始阶段进行密钥交换。在加密方面,基于ECC最有名的就是综合加密方案（ECIES,elliptic curve integrate encrypt scheme）。ECIES是Certi-com公司提出的公钥加密方案,可以抵挡选择明文攻击和选择密文攻击。ECIES各个步骤的实现可以用不同的算法,在软件中是可以配置的。而它实现的多样性也验证了它的灵活性以及可靠性。     

Low-complexity video coding via power-rate-distortion optimization

Wireless multimedia sensor networks (WMSNs) have been potentially applicable for several emerging applications. The resources, i.e., power and bandwidth available to visual sensors in a WMSN are, however, very limited. Hence, it is important but challenging to achieve efficient resource allocation and optimal video data compression while maximizing the overall network lifetime. In this paper, a power-rate-distortion (PRD) optimized resource-scalable low-complexity multiview video encoding scheme is proposed. In our video encoder, both the temporal and interview information can be exploited based on the comparisons of extracted media hashes without performing motion and disparity estimations, which are known to be time-consuming. We present a PRD model to characterize the relationship between the available resources and the RD performance of our encoder. More specifically, an RD function in terms of the percentages for different coding modes of blocks and the target bit rate under the available resource constraints is derived for optimal coding mode decision. The major goal here is to design a PRD model to optimize a “motion estimation-free” low-complexity video encoder for applications with resource-limited devices, instead of designing a general-purpose video codec to compete compression performance against current compression standards (e.g., H.264/AVC). Analytic results verify the accuracy of our PRD model, which can provide a theoretical guideline for performance optimization under limited resource constraints. Simulation results on joint RD performance and power consumption (measured in terms of encoding time) demonstrate the applicability of our video coding scheme for WMSNs.