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实验一
1、实验题目
利用C/C++编程实现DES加密算法或MD5加密算法。我选择的是用C++语言实现
DES的加密算法。 2、实验目的
通过编码实现DES算法或MD5算法，深入掌握算法的加密原理，理解其实际应用 价值，同时要求用C/C++语言实现该算法，让我们从底层开始熟悉该算法的实现过程 3、实验环境
操作系统：WIN7旗舰版
开发工具：Visual Studio 2010旗舰版 开发语言：C++ 4、实验原理
DES加密流程
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如上图所示为DES的加密流程，其中主要包含初始置换，压缩换位1，压缩换位2，扩 展置换，S盒置换，异或运算、终结置换等过程。 初始置换是按照初始置换表将64位明文重新排列次序 扩展置换是将原32为数据扩展为48位数据，它主要由三个目的： 1、产生与子密钥相同的长度 2、提供更长的结果，使其在加密过程中可以被压缩
3、产生雪崩效应，使得输入的一位将影响两个替换
S盒置换是DES算法中最核心的容，在DES中，只有S盒置换是非线性的，它比DES 中其他任何一步都提供更好的安全性
终结置换与初始置换相对应，它们都不影响DES的安全性，主要目的是为了更容易将 明文与密文数据一字节大小放入DES的f算法中
DES解密流程与加密流程基本相同，只不过在进行16轮迭代元算时，将子密钥生成的 K的次序倒过来进行迭代运算 5、实验过程记录
在对DES算法有了清晰的认识后，编码过程中我将其分为几个关键部分分别进行编码，最后将整个过程按顺序执行，即可完成DES的加密，代码的主要几个函数如下： //Byte转为Bit
ByteToBit(ElemType ch,ElemType bit[8]) //Bit转为Byte BitToByte(ElemType bit[8],ElemType &ch) //初始置换
InitialEX(ElemType Inorder[64],ElemType Disorder[64]) //终结置换 AntiEx(ElemType Disorder[64]) //扩展置换
ExpandEX(ElemType RightMsg[32],ElemType ExpandMsg[48]) //16轮迭代加密
MoveLeft(ElemType C[28],ElemType D[28],ElemType L0[32],ElemType R0[32]) 3
//16轮迭代解密
mMoveLeft(ElemType C[28],ElemType D[28],ElemType L0[32],ElemType R0[32]) //生成48位子密钥
GetCD48(ElemType C[28],ElemType D[28],ElemType Secret[48]) //48位明文与子密钥进行异或运算
XOR(ElemType ExpandMsg[48],ElemType Secret[48],ElemType Result[48]) //S盒四位输出
getSOut(ElemType Result[48],ElemType Sout[32]) //直接置换
DirExchange(ElemType Sout[32],ElemType DirOut[32]) //Li与Ri进行抑或运算 XORLR(ElemType DirOut[32],ElemType Left[32],ElemType Result[32]) 函数执行次序和调用关系关系如下：
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6.源代码
// DES.cpp : 定义控制台应用程序的入口点。 //
#include \#include \#include
//置换矩阵
int IP_EX[64]= { 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 57, 49, 41, 33, 25, 17, 9, 1, 59, 51, 43, 35, 27, 19, 11, 3, 61, 53, 45, 37, 29, 21, 13, 5, 63, 55, 47, 39, 31, 23, 15, 7 };
int IP_ANTEX[64]= { 40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 41, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25 }; //扩展矩阵
int EXTEND[48]= {
32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 1, 2 }; //S
盒 int S[8][4][16]= { { {14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7}, {0, 15, 7, 4, 14,
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2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8}, {4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0}, {15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13}
}, { {15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10}, {3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 }, {0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15 }, {13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9} }, { {10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8}, {13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1}, {13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7}, {1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12} }, { { 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15}, {13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9}, {10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4}, {3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14} }, { {2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9}, {14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6}, {4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14}, {11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3} },
{ {12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11}, {10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8}, {9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6}, {4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13}
}, { {4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1}, {13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6}, {1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2}, {6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12}
}, { {13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7}, {1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2}, {7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8}, {2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11} } };
int DIREX[32]= { 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3,
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9, 19, 13, 30, 6, 22, 11, 4, 25 };
//左移移位表
int MOVELEFT[16]= { 1,1,2,2,2,2,2,2, 1,2,2,2,2,2,2,1 };
//压缩换位表2
int CutEX[48]= { 14, 17, 11, 24, 1, 5,
3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32 };
typedef char ElemType; ElemType subsec[16][48]; //Byte转bit
int ByteToBit(ElemType ch,ElemType bit[8]) {
for(int index = 7;index >= 0;index--) { bit[index] = (ch>>index)&1; //cout<<(int)bit[index]; }
return 0; } //bit转Byte
int BitToByte(ElemType bit[8],ElemType &ch) { ElemType tempch=0; ElemType tempbit[8]; for(int i=0;i<8;i++) { tempbit[i]=bit[i]; }
tempbit[7]=0;
for(int index = 7;index >=0;index--) {
tempch=tempch|(tempbit[index]<<(index)); } ch=tempch; //cout<<(char)tempch< //按64位分一组 void Get64Bit(ElemType ch[8],ElemType bit[64]) { ElemType temp[8]; int count=0; for(int i=0;i<8;i++) { ByteToBit(ch[i],temp); for(int j=0;j<8;j++) { bit[count*8+j]=temp[7-j]; } count++; } } //初始置换 void InitialEX(ElemType Inorder[64],ElemType Disorder[64]) { for(int i=0;i<64;i++) { Disorder[i]=Inorder[IP_EX[i]-1]; } } . . .
DES_加密解密算法的C++实现--实验报告
