The Ansewer of Problem 4.7
2017-10-11 23:31
387 查看
DES算法加密过程:
Ri+1=Li
Li+1=Li⊕F(Ri,Ki)
经过16轮次后，得到L16和R16，将其置换得到R16L16，输出密文。
在解密过程中，将Ri+1,Li+1代入上述式得：
Ri-1=Li
Li+1⊕F(Ri,Ki)=Li⊕F(Ri,Ki)⊕F(Li+1,Ki)=Li⊕F(Ri,Ki)⊕F(Ri,Ki)=Li
代入后左右两边得到的结果是加密过程之中的上一轮的左右部分
经过16轮次后，得到R0和L0，将其置换得到L0R0，输出密文。
DES算法的加密与解密其实逻辑相同，只是加密与解密密钥的顺序互逆
因此DES的解密算法是加密算法的逆运算
Ri+1=Li
Li+1=Li⊕F(Ri,Ki)
经过16轮次后，得到L16和R16，将其置换得到R16L16，输出密文。
在解密过程中，将Ri+1,Li+1代入上述式得：
Ri-1=Li
Li+1⊕F(Ri,Ki)=Li⊕F(Ri,Ki)⊕F(Li+1,Ki)=Li⊕F(Ri,Ki)⊕F(Ri,Ki)=Li
代入后左右两边得到的结果是加密过程之中的上一轮的左右部分
经过16轮次后，得到R0和L0，将其置换得到L0R0，输出密文。
DES算法的加密与解密其实逻辑相同，只是加密与解密密钥的顺序互逆
因此DES的解密算法是加密算法的逆运算
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
相关文章推荐
- hdu 2740 Root of the Problem （水）
- Problem 1046 Tempter of the Bone， from http://acm.fzu.edu.cn/problem.php?pid=1046
- POJ 2151--Check the difficulty of problem
- POJ 3100 Root of the Problem（简单题）
- The problem of the user is not associated with a trusted sql server connection 混合登录选项设置的问题
- rules for tracking down the cause of a problem
- TF80012: The document cannot be opened because there is a problem with the installation of the Microsoft Visual Studio v
- Error:Unable to start the daemon process. This problem might be caused by incorrect configuration of
- 打包出现这个错误Error:A problem was found with the configuration of task ':app:packageRelease'.
- the railway problem(the example of stack)
- Visualisation of Genetic Algorithms for the Traveling Salesman Problem in Java --by Johannes Sarg
- poj 3100 Root of the Problem
- The Overview of Rule Placement Problem in SDN（规则放置问题的概述）
- 机器学习(四)正则化与过拟合问题 Regularization / The Problem of Overfitting
- Problem 11 of What is the greatest product of four adjacent numbers
- 7 - 1 - The Problem of Overfitting (10 min)
- Flex Builder cannot locate the required debug version of the Flash Player problem
- 5 Whys Quickly Getting to the Root of a Problem
- The problem of Memory Leak
- Error:Unable to start the daemon process. This problem might be caused by incorrect configuration of