实验3 对称密码算法DES.docx

1、实验3 对称密码算法DES实验3 对称密码算法DES(验证型)一、 实验目的通过用DES算法对实际的数据进行加密和解密来深刻了解DES的运行原理。二、 实验原理DES算法属于分组加密算法，即在明文加密和密文解密过程中，信息都是按照固定长度分组后进行处理的。混淆和扩散是它采用的两个最重要的安全特性。混淆是指通过密码算法使明文和密文以及密钥的关系非常复杂，无法从数学上描述或者统计。扩散是指明文和密钥中的每一位信息的变动，都会影响到密文中许多位信息的变动，从而隐藏统计上的特性，增加密码的安全。DES算法将明文分成64位大小的众多数据块，即分组长度为64位。同时用56位密钥对64位明文信息加密，最终形

2、成64位的密文。需要注意的地方是掌握DES算法的16轮加、解密流程以及子密钥的产生流程。三、 实验环境运行Windows或者Linux操作系统的PC机，具有gcc（Linux）、VC（Windows）等C语言编译环境。四、实验内容1、算法分析（1）写出DES算法的16轮加、解密流程；（2）写出子密钥的产生流程；2、下载DES算法的实现程序，并调用其程序对一个文件进行加密和解密，提交程序代码和执行结果。3、调用下载的DES算法的实现程序对输入的十六进制数加密，比较输入和输出，当改变一个位时比较输出的变化，并说明原因。五、实验步骤1、(1)、(2)、2、打开VC+，编写程序如下：#include

3、stdio.h #include memory.h /#include time.h #include stdlib.h #define PLAIN_FILE_OPEN_ERROR -1 #define KEY_FILE_OPEN_ERROR -2 #define CIPHER_FILE_OPEN_ERROR -3 #define OK 1 typedef char ElemType; /初始置换表IP int IP_Table64 = 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

4、,39,31,23,15,7, 56,48,40,32,24,16,8,0, 58,50,42,34,26,18,10,2, 60,52,44,36,28,20,12,4, 62,54,46,38,30,22,14,6; /逆初始置换表IP-1 int IP_1_Table64 = 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, 33,1,41,9,49,1

5、7,57,25, 32,0,40,8,48,16,56,24; /扩充置换表E 32-48int E_Table48 = 31, 0, 1, 2, 3, 4, 3, 4, 5, 6, 7, 8, 7, 8,9,10,11,12, 11,12,13,14,15,16, 15,16,17,18,19,20, 19,20,21,22,23,24, 23,24,25,26,27,28, 27,28,29,30,31, 0; /置换函数P int P_Table32 = 15,6,19,20,28,11,27,16, 0,14,22,25,4,17,30,9, 1,7,23,13,31,26,2,8,

6、18,12,29,5,21,10,3,24; /S盒 int S8416 =/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,

7、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,

8、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, 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,

9、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,

10、 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; /置换选择1 int PC_156 = 56,48,40,32,24,16,8, 0,57,49,41,33,25,17, 9,1,58,50,42,34,26, 18,10,2,59,51,43,35, 62,54,46,38,30,22,14, 6,61,53,45,37,29,21, 13,5,60,52,44,36,28, 20,12,4,27,19,1

11、1,3; /置换选择2 int PC_248 = 13,16,10,23,0,4,2,27, 14,5,20,9,22,18,11,3, 25,7,15,6,26,19,12,1, 40,51,30,36,46,54,29,39, 50,44,32,46,43,48,38,55, 33,52,45,41,49,35,28,31; /对左移次数的规定 int MOVE_TIMES16 = 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1; int ByteToBit(ElemType ch,ElemType bit8); int BitToByte(ElemType bit8,El

12、emType *ch); int Char8ToBit64(ElemType ch8,ElemType bit64); int Bit64ToChar8(ElemType bit64,ElemType ch8); int DES_MakeSubKeys(ElemType key64,ElemType subKeys1648); int DES_PC1_Transform(ElemType key64, ElemType tempbts56); int DES_PC2_Transform(ElemType key56, ElemType tempbts48); int DES_ROL(ElemT

13、ype data56, int time); int DES_IP_Transform(ElemType data64); int DES_IP_1_Transform(ElemType data64); int DES_E_Transform(ElemType data48); int DES_P_Transform(ElemType data32); int DES_SBOX(ElemType data48); int DES_XOR(ElemType R48, ElemType L48,int count); /异或操作int DES_Swap(ElemType left32,ElemT

14、ype right32); /交换 L分组与R分组交换.int DES_EncryptBlock(ElemType plainBlock8, ElemType subKeys1648, ElemType cipherBlock8); int DES_DecryptBlock(ElemType cipherBlock8, ElemType subKeys1648, ElemType plainBlock8); int DES_Encrypt(char *plainFile, char *keyStr,char *cipherFile); int DES_Decrypt(char *cipherF

15、ile, char *keyStr,char *plainFile); /字节转换成二进制int ByteToBit(ElemType ch, ElemType bit8) int cnt; for(cnt = 0;cnt cnt)&1; /右移cnt位,与1相与.将字节装入8位二进制数组中.倒序装入 /7=00000111,bit=11100000 /printf(%s,bit); return 0; /二进制转换成字节 int BitToByte(ElemType bit8,ElemType *ch) int cnt; for(cnt = 0;cnt 8; cnt+) *ch |= *(b

16、it + cnt)cnt; / 为*(1)+*(10)+*(100)+0000+00000+0000000.=7 return 0; /将长度为8的字符串转为二进制位串 int Char8ToBit64(ElemType ch8,ElemType bit64) int cnt; for(cnt = 0; cnt 8; cnt+) ByteToBit(*(ch+cnt),bit+(cnt3); /cnt3即为cnt*8 return 0; /将二进制位串转为长度为8的字符串 int Bit64ToChar8(ElemType bit64,ElemType ch8) int cnt; memset

17、(ch,0,8); /以ch为起点的8位空间数组置0. for(cnt = 0; cnt 8; cnt+) BitToByte(bit+(cnt3),ch+cnt); return 0; /IP置换 int DES_IP_Transform(ElemType data64) int cnt; ElemType temp64; for(cnt = 0; cnt 64; cnt+) tempcnt = dataIP_Tablecnt; memcpy(data,temp,64); /由temp所指内存区域复制64个字节到data所指内存区域,与strcpy 同. return 0; /IP逆置换 i

18、nt DES_IP_1_Transform(ElemType data64) int cnt; ElemType temp64; for(cnt = 0; cnt 64; cnt+) tempcnt = dataIP_1_Tablecnt; memcpy(data,temp,64); /由temp所指内存区域复制64个字节到data所指内存区域,与strcpy同 return 0; /密钥置换1 pc-1int DES_PC1_Transform(ElemType key64, ElemType tempbts56) int cnt; for(cnt = 0; cnt 56; cnt+) te

19、mpbtscnt = keyPC_1cnt; return 0; /密钥置换2 pc-2int DES_PC2_Transform(ElemType key56, ElemType tempbts48) int cnt; for(cnt = 0; cnt 48; cnt+) tempbtscnt = keyPC_2cnt; return 0; /E扩展置换 int DES_E_Transform(ElemType data48) /这里data两种用处,故为48位极人臣 int cnt; ElemType temp48; for(cnt = 0; cnt 48; cnt+) tempcnt =

20、 dataE_Tablecnt; /这里data下标最高为32. memcpy(data,temp,48); return 0; /P置换 int DES_P_Transform(ElemType data32) int cnt; ElemType temp32; for(cnt = 0; cnt 32; cnt+) tempcnt = dataP_Tablecnt; memcpy(data,temp,32); return 0; /循环左移 /左右两边同时循环左移相同的位数./10010循环左移1位为00101,左移2位为01010int DES_ROL(ElemType data56, i

21、nt times) ElemType temp56; /temp只保存将要循环到右边的位. /保存将要循环移动到右边的位 memcpy(temp,data,times); /保存前28位的移位 memcpy(temp+times,data+28,times); /保存后28位的移位极人臣 /前28位移动 memcpy(data,data+times,28-times); /一般移位 memcpy(data+28-times,temp,times); /循环位移动 /后28位移动 memcpy(data+28,data+28+times,28-times); memcpy(data+56-tim

22、es,temp+times,times); return 0; /生成子密钥 int DES_MakeSubKeys(ElemType key64,ElemType subKeys1648) ElemType temp56; int cnt; DES_PC1_Transform(key,temp);/PC1置换 for(cnt = 0; cnt 16; cnt+)/16轮跌代，产生16个子密钥 DES_ROL(temp,MOVE_TIMEScnt);/Ci Di 左右两边,循环左移 DES_PC2_Transform(temp,subKeyscnt);/PC2置换，产生子密钥 return 0

23、; /异或 int DES_XOR(ElemType R48, ElemType L48 ,int count) int cnt; for(cnt = 0; cnt count; cnt+) Rcnt = Lcnt; /异或即为模2加法 return 0; /S盒置换 48=8*6 32=8*4int DES_SBOX(ElemType data48) int cnt; int line,row,output; int cur1,cur2; for(cnt = 0; cnt 8; cnt+) cur1 = cnt*6; cur2 = cnt2; /计算在S盒中的行与列 b1b2b3b4b5b6

24、 b1b2 /b3b4b5b6 line = (datacur11) + datacur1+5; row = (datacur1+13) + (datacur1+22) + (datacur1+33; /取得output二进制倒数第4位为0还是1 datacur2+1 = (output&0X04)2; /output=7=0111 oxo4=0100 datacur2+2 = (output&0X02)1; /相&得到0100 右移2位得到1 datacur2+3 = output&0x01; return 0; /交换 L分组与R分组交换.int DES_Swap(ElemType lef

25、t32, ElemType right32) ElemType temp32; memcpy(temp,left,32); memcpy(left,right,32); memcpy(right,temp,32); return 0; /加密单个分组 int DES_EncryptBlock(ElemType plainBlock8, ElemType subKeys1648, ElemType cipherBlock8) ElemType plainBits64; /明文比特 ElemType copyRight48; / int cnt; Char8ToBit64(plainBlock,plainBits); /初始置换（IP置换） DES_IP_Transform(plainBits); /16轮迭代 for(cnt = 0; cnt = 0; cnt-) memcpy(copyRight,cipherBits+32,32); /这里为什么还是右半部分? /将右半部分进行扩展置换，从32位扩展到48位 DES_E_Transform(copyRight); /将右半部分与子密钥进