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1、数学与信息安全Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.怎样设计密码?Evaluation only.Evaluation only. Created with Aspose.Sli
2、des for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.第1阶段古典密码 密码学还不是科学,而是艺术 出现一些密码算法和加密设备 密码算法的基本手段出现，针对的是字符 简单的密码分析手段出现 主要特点：数据的安全基于算法的保密数学与密码技术的三个发展阶段数学与密码技术的三个发展阶段Evaluation on
3、ly.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.古典加密主要技术n代替密码：明文中的每个字符被替 换成密文中的另一个字符。n置换密码：不改变明文字母，只 改变了这些字母的出现顺序。 Evaluation only.
4、Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.古典密码用到的数学n变换n置换n整数的模运算n统计学（破解时）用得不多Evaluation only.Evaluation only. Created with Aspos
5、e.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd. 计算机使得基于复杂计算的密码成为可能 相关技术的发展1949年Shannon（香农）的“The Communication Theory of Secret Systems” 1971-73年IBM Watson实验室的Horst Feis
6、tel等几篇技术报告 主要特点：数据的安全基于密钥而不是算法的保密 第2阶段 近代密码阶段（19491975）Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.l Shannon：美国工程师
7、 u 1948年发表 “A Mathematical Theory of ommunication”，标志信息论的诞生u 1949年发表 “Communication Theory of Secrecy system”，以信息论为基础，用概率统计为数学手段对保密通信问题进行了分析。u由香农提出的保密系统模型目前仍然是现代密码学的基本模型.Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NE
8、T 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.Shannon通信系统模型n信源：消息的来源n编码器：把消息变换成信号n信道：传递信号的媒介,在物 理线路上划分的逻辑通道。n译码器：把信道输出的信号 反变换n信宿：信息的接受端n噪声：信道中的干扰Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Creat
9、ed with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.Shannon保密通信系统模型 公开信道密钥信道Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Prof
10、ile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.香农信息论信源熵信道容量无失真信源 编码定理率失真函数信源编码信道编码限失真信源 编码定理信道 编码定理密码u概括:u信息的测度u信道容量u信源和信道编 码理论用到的数学概率论与数理 统计Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides
11、for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.1976年：Diffie & Hellman 的 “New Directions in Cryptography” 提出了公钥密码学思想； 1977年Rivest,Shamir & Adleman提出了RSA公钥算法； 90年代逐步出现椭圆曲线等其他公钥算法； 主要特点：公钥密码使得发送端和接收端无密钥传输的保密通信成为可能第3阶段 现代密码后期阶段（1976）Evaluation
12、only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.q对称密码体制： 加密密钥和解密密钥相同. 密钥分发与管理困难。q非对称密码体制(也称公钥密码体制): 加密密钥 （public key）和解密密钥（privat
13、e key)不相同， 从一个密钥导出另一个密钥是计算上不可行的， 加密能力和解密能力是分开的，开放性好。密钥 分发与管理相对容易.密码体制分类Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd
14、.加密与解密的密钥相同，即：P=D(K,E(K,P)对称密码体制模型Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.加密与解密的密钥不同，则：P=D(KD,E(KE,P)非对称密码体制模型
15、Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.如何设计公钥密码u最基本思想:利用数学难解问题.u设计工具:数论、代数Evaluation only.Evaluation only. Cr
16、eated with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.数论的游戏之美n数论就是一门研究整数性质的学科 n数论的很多问题最能体现数学之美数学皇冠Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose
