密码分析学

The cryptanalysis and design of block ciphers are one of the hotspots in modern cryptography.

分组密码的设计与分析是当前密码学研究的热点课题之一。

Design and cryptanalysis on group signature is always the hotspot in the field of cryptography.

对群签名的设计与分析始终是密码学领域的一大热点。

Source code for all these algorithms is in the public domain and has undergone years of cryptanalysis.

为所有这些算法的来源代码在公众领域里和经受了密码学分析。

On the other hand,some cryptanalysis can be reduced to lattice reduction problems.

在密码学应用中，对一些密码方案的分析最终都可以等价成一个格基规约问题。

At last, the requests and best choices of cryptographic algorithms is concluded.

最后分析了协议中的密码学算法要求和最佳选择。

The contributions of the dissertation are as follows.1 Cryptology is the foundation of authentication.

论文的主要工作包括以下几个方面： 1身份认证的密码学理论基础分析。

Methods in discrete mathematics, such as finite difference equation, simulation, coding, etc. The related cases are "Mortgage loan and other financial problems","Simulation of inventory problem","Adding cipher and extricating for Hill code", and "Input-output analysis".

某些离散问题的数学方法(差分方程问题，仿真方法，密码学等)，这部分内容相应的教学案例是"个人住房抵押贷款与其他金融问题"，"库存问题的仿真方法"，"Hill密码的加密、解密和破译"和"投入产出分析"等

Because the implanted hash function of HMAC is implemented as an individual function block, this block could be replaced easily according to the security request. The high capability of withstanding attacks of HMAC-ECDSA algorithm is proved by using modular arithmetic.

从密码学理论分析，HMAC可以使用密钥且HMAC算法的验证只在当时有效；在程序设计中实现HMAC时，可以将嵌入的哈希算法作为一个独立的模块，根据安全强度的需求替换哈希算法模块；在对攻击高抵抗性的证明中，利用模运算对HMAC-ECDSA算法的安全强度进行了验证。

Finally this thesis analyses the efficient revocable group signature scheme with forward security proposed by Chen Shaozhen and Li Daxirig. An adversary can personate a legal group member by forge a group membership certificate, and then can forge group signatures that can be verified by a verifier. And the group manager can also forge group signatures that can be verified by a verifier. So the scheme is insecure. Meanwhile, there are redundancy steps in the scheme, thus the efficiency is low.

接着，对陈少真和李大兴提出的一种有效取消的前向安全群签名方案进行了密码学分析，一方面，攻击者可以通过伪造群成员证书来伪造能够通过验证的群签名；同时，群管理员也可以伪造一个可以通过验证的群签名，因此，该群签名体制是不安全的；另一方面，该体制存在冗余数据。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失