实 验 报 告
：xxxx 学号：0XXXXX 班级：XXXXXXX 日期：2013/11/*
题目：DES算法实验
一、实验环境
1．硬件配置：
处理器：Inter(R) Core(TM) i5-2430M CPU 2.40GHz (4 CPUs) ,~2.4GHz 存：2048MB RAM 2．使用软件：
(1) 操作系统：win7 旗舰版
(2) 软件工具：Microsoft Visual c++ 6.0
二、实验涉及的相关概念或基本原理
DES是一个分组密码算法，使用64位密钥（除去8位奇偶校验，实际密钥长度为56位）对64比特的数据分组（二进制数据）加密，产生64位密文数据。DES是一个对称密码体制，加密和解密使用同意密钥，解密和加密使用同一算法（这样，在硬件与软件设计时有利于加密单元的重用）。DES的所有的性均依赖于密钥。
DES的加密过程可分为加密处理,加密变换和子密钥生成几个部分组成。 1.加密处理过程 (1)初始置换IP。加密处理首先要对64位的明文按表1所示的初始换位表IP进行变换。表中的数值表示输入位被置换后的新位置。
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(2)加密处理。上述换位处理的输出，中间要经过16轮加密变换。初始置换的64位的输出作为下一次的输入，将64位分为左、右两个32位，分别记为L0和R0，从L0、R0到L16、R16，共进行16轮加密变换。其中，经过i轮处理后的点左右32位分别为Li和Ri则可做如下定义:
Li=Ri-1
Ri=Li-1 ⊕F(Ri-1，K) 其中，F为F变换
(3)最后换位。进行16轮的加密变换之后，将L16和R16合成64位的数据，再按照表2所示的最后换位表进行IP-1的换位，得到64位的密文，这就是DES算法加密的结果。
2.加密变换过程
64位的密钥先由置换选择1减少至56六位，进行循环左移，然后通过置换选择2减少至48位。而通过扩展运算将32位按表3扩展换位表扩展为48位的右半部分通过异或操作和48位的密钥结合，并分成6位的8个分组，通过8个S-盒将这48位替代成新的32位数据。
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按此进行,输出32位,再按照表4 换位表P进行变换,这样就完成了F(R,K)的变换。
3.子密钥生成过程
密钥通常表示为64位的自然数，首先通过压缩换位Key_Exchange去掉每个字节的第8位,用作奇偶校验。因此，密钥去掉第8、16、24……64位减至56位，所以实际密钥长度为56位。而每轮要生成48位的子密钥。输入的64位密钥，首先通过压缩换位得到56位的密钥，每层分成两部分，一部分28位为C0，一部分为D0。C0和D0依次进行循环左移操作生成了C1和D1，将C1和D1合成56位，再通过压缩换位Compression输出48位的子密钥K1，再将C1和D1进行循环左移和Compression压缩换位,得到子密钥K2……以此类推，得到16个子密钥。密钥压缩换位表如表5表6所示。
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在产生子密钥的过程中左移次数如表7所示。
4.解密处理过程
从密文到明文的解密过程可采用与加密完全相同的算法。不过解密要用加密的逆变换,就是把上面的最后换位表和初始换位表完全倒过来变换。 三、实验容 流程图：
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主要代码： ①初始置换
unsigned char Initial [] = {
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 };
②逆初始置换
unsigned char Final[] = {
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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, 42, 10, 50, 18, 58, 26,33, 1, 41, 9, 49, 17, 57, 25 };
③扩展变换E
unsigned char Expansion[] = {
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, 32, 1 };
④P_盒置换
unsigned char P_Box[]= {
16, 7, 20, 21, 29, 12, 28, 17,1, 15, 23, 26, 5, 18, 31, 30,2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25 };
⑤S盒置换
unsigned char S_Box[8][4][16] = {
/* S1 */
{ {14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9,0, 7}, {0, 15, 7, 4, 14, 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}}, /* S2 */
{ {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}}, /* S3 */
{{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}}, /* S4 */
{ {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}}, /* S5 */
{{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},
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{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}}, /* S6 */
{{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}}, /* S7 */
{{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}}, /* S8 */
{{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}} };
⑥置换选择1
unsigned char Key_Exchange[56] = {
57, 49, 41, 33, 25, 17, 9,1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27,19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15,7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29,21, 13, 5, 28, 20, 12, 4 };
⑦置换选择2
unsigned char Compression[] = {
14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 9, 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 };
⑧循环左移位数
unsigned char Key_Move[]= {
1 , 1 , 2 , 2 , 2 , 2 , 2 , 2 , 1 , 2 , 2 , 2 , 2 , 2 , 2 , 1 };
⑨产生子密钥
int Key_Process(bool key[64],bool Sub_Key[16][48] ) {
int round ; bool temp[56];
Key_Transform1(key,temp); for(round=0;round<16;round++)
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{
Key_Rotate(temp,Key_Move[round]) ; Key_Transform2(temp,Sub_Key[round]); }
return 0; }
异或
int XOR(bool KR[48],bool KL[48] ,int count) {
int i;
for(i=0;i return 0; } 加密算法 int DES_Encrypt(bool Message[8],bool Sub_Key[16][48], bool Final_Result[8]) { bool Expanded_Right[48]; bool Result[64]; int round; Char8ToBit64(Message,Result); Initial_Exchange(Result); for(round=0;round<16;round++) { memcpy(Expanded_Right,Result+32,32); M_Expand(Expanded_Right); XOR(Expanded_Right,Sub_Key[round],48); S_function(Expanded_Right); P_function(Expanded_Right); XOR(Result,Expanded_Right,32); if(round!=15) Swap(Result,Result+32); } Final_Exchange(Result); Bit64ToChar8(Result,Final_Result); return 0; } 解密算法 int DES_Decrypt(bool Final_Result[8],bool Sub_Key[16][48], word资料 bool Message[8]) { bool Expanded_Right[48]; bool Result[64]; int round; Char8ToBit64(Final_Result,Result); Initial_Exchange(Result); for(round=15;round>=0;round--) { memcpy(Expanded_Right,Result+32,32); M_Expand(Expanded_Right); XOR(Expanded_Right,Sub_Key[round],48); S_function(Expanded_Right); P_function(Expanded_Right); XOR(Result,Expanded_Right,32); if(round!= 0) Swap(Result,Result+32); } Final_Exchange(Result); Bit64ToChar8(Result,Message); return 0; } 加密文件 int DES_EncryptFile(char *Final_Result) { FILE *input,*output; int count; unsigned name[30]; unsigned char key[64]; bool InputBlock[8],OutputBlock[8],keyBlock[8]; bool bKey[64]; bool Sub_Key[16][48]; printf(\"输入文件名\\n\"); scanf(\"%s\ printf(\"输入密钥\\n\"); scanf(\"%s\ getchar(); if((input=fopen(name,\"rb\")) == NULL) return 0; if((output=fopen(Final_Result,\"wb\")) == NULL) return 0; memcpy(keyBlock,key,8); Char8ToBit64(keyBlock,bKey); Key_Process(bKey,Sub_Key); while(!feof(input)) word资料 { if((count=fread(InputBlock,sizeof(char),8,input)) == 8) { DES_Encrypt(InputBlock,Sub_Key,OutputBlock); fwrite(OutputBlock,sizeof(char),8,output); } } if(count) { memset(InputBlock+ count,'\\0',7 - count); InputBlock[7] = 8 - count; DES_Encrypt(InputBlock,Sub_Key,OutputBlock); fwrite(OutputBlock,sizeof(char),8,output); } fclose(input); fclose(output); return 1; } 解密文件 int DES_DecryptFile(char *Message) { FILE *input, *output; int count,times = 0; long fileLen; unsigned name[30]; unsigned char key[64]; bool inputBlock[8],outputBlock[8],keyBlock[8]; bool bKey[64]; bool Sub_Key[16][48]; printf(\"输入文件名\\n\"); scanf(\"%s\ printf(\"输入密钥\\n\"); scanf(\"%s\ getchar(); if((output = fopen(name,\"rb\")) == NULL) return 0; if((input = fopen(Message,\"wb\")) == NULL) return 0; memcpy(keyBlock,key,8); Char8ToBit64(keyBlock,bKey); Key_Process(bKey,Sub_Key); fseek(output,0,SEEK_END); fileLen=ftell(output); rewind(output); while(1) word资料 { fread(outputBlock,sizeof(char),8,output); DES_Decrypt(outputBlock,Sub_Key,inputBlock); times += 8; if(times < fileLen) fwrite(inputBlock,sizeof(char),8,input); else break; } if(inputBlock[7]<8) { for(count=8-inputBlock[7];count<7;count++) { if(inputBlock[count]!='\\0') { break; } } } if(count == 7) fwrite(inputBlock,sizeof(char),8 - inputBlock[7],input); else { fwrite(inputBlock,sizeof(char),8,input); } fclose(input); fclose(output); return 1; } 四、实验总结分析 1、心得体会 对DES加密算法有了进一步的认识与了解，对DES算法的结构和优缺点也有了了解，相信在以后的学习与实践中，能够更好地运用这些算法。 word资料 因篇幅问题不能全部显示，请点此查看更多更全内容