1、实验背景
●多表替代密码：由多个简单的替代密码构成，例如，可能有5个不同的简单替代密码，分别用于替代明文中不同位置的字符。主要学习维吉尼亚表。
●换位密码：一种早期的加密方法，明文的字母保持相同，但顺序被打乱了。
●DES加密算法工作的基本原理：其入口参数有三个:key、data、mode。 key为加密解密使用的密钥，data为加密解密的数据，mode为其工作模式。当模式为加密模式时，明文按照位进行分组，形成明文组，key用于对数据加密，当模式为解密模式时，key用于对数据解密。实际运用中，密钥只用到了位中的56位，这样才具有高的安全性。主要掌握S盒替代。
2、实验目的
1、实验课前复习DES加密、传统加密算法—多表替代（维吉尼亚表替代）、换位密码算法。
2、任选C、C++、VC++等其中一种来实现编程实现加密算法。
3、调试程序，给定一段明文，和密钥，通过加密算法，给出密文。
4、目的：掌握加密算法的基本原理及其加密方法的详细步骤。
3、实验所需设备
安装Windows9x/2000/XP/2003操作系统和Visualstudio 6.0环境的PC。
4、实验拓扑
无
5 、实验步骤
●多表替代 注意红色字体代码
1 启动VC++6.0。
2 新建Win32 Console Application。
3 在Project Name和Locate位置填上工程名weijiniya和保存位置（自选）。
4 按OK按钮。选An simple Project。
5 按Finish按钮。
6 在weijiniya.cpp中添加如下代码：
#include "stdafx.h"
#include #include #include #include void Shift() /*移位密码*/ { char c[100]; int length, i=0, key=0; //clrscr(); printf("********Shift Cipher********\\nPlease input primal sentence: "); gets(c); length = strlen(c); printf("Input the key(0~26): "); scanf("%d", &key); getchar(); if(key<0) { printf("The value of key is error!\\nPress any key to return..."); getch(); return; } for(i=0; i if(c[i]>96&&c[i]<123) c[i] = (c[i]+key-97)%26+65; else if(c[i]>&&c[i]<91) c[i] = (c[i]+key-65)%26+65; } printf("Result is: %s\\n", c); for(i=0; i if(c[i]>&&c[i]<91) c[i] = (c[i]-key-65+26)%26+97; } printf("\\nAfter translated the sentence,we can see the primal sentence as follow:\\n%s\\n", c); printf("Press any key to return..."); getch(); } int (int a, int b) /*辗转相除法求a,b的最大公因数*/ { int k = 0; do { k = a%b; a = b; b = k; }while(k!=0); return a; } int Ni(int a, int b) /*求a相对于b的逆*/ { int i = 0; while(a*(++i)%b!=1); return i; } void Affine() /*仿射密码*/ { char c[100]; int length, i=0, ka=0, kb=0, tmp; //clrscr(); printf("********Affine Cipher********\\nPlease input primal sentence: "); gets(c); length = strlen(c); printf("Input the key(2 numbers): "); scanf("%d%d", &ka, &kb); getchar(); if((ka,26)!=1) { printf("The value of the key is error!\\nPress any key to return..."); return; } for(i=0; i if(c[i]>96&&c[i]<123) c[i] = (ka*(c[i]-97)+kb)%26+65; else if(c[i]>&&c[i]<91) c[i] = (ka*(c[i]-65)+kb)%26+65; } printf("Result is: %s\\n", c); for(i=0; i if(c[i]>&&c[i]<91) { tmp = Ni(ka,26)*((c[i]-65)-kb); if(tmp<0) c[i] = tmp%26+26+97; else c[i] = tmp%26+97; } } printf("\\nAfter translated the sentence,we can see the primal sentence as follow:\\n%s\\n", c); printf("Press any key to return..."); getch(); } void Vigenere() /*维吉利亚密码*/ { char c[100], key[100]; int lenc, lenk, i=0, j=0, tmp; //clrscr(); printf("********Vigenere Cipher********\\nPlease input primal sentence: "); gets(c); lenc = strlen(c); strcpy(c, strupr(c)); printf("Input the key: "); gets(key); lenk = strlen(key); strcpy(key, strupr(key)); for(; i j = j%lenk; if(c[i]>&&c[i]<91) { c[i] = (c[i]-65+key[j]-65)%26+65; j++; } } printf("Result is: %s\\n", c); for(i=0, j=0; i j = j%lenk; if(c[i]>&&c[i]<91) { tmp = c[i]-65-(key[j]-65); if(tmp>=0) c[i] = tmp%26+97; else c[i] = (tmp+26)%26+97; j++; } } printf("\\nAfter translated the sentence,we can see the primal sentence as follow:\\n%s\\n", c); printf("Press any key to return..."); getch(); } void Permutation() /*置换密码*/ { char c[100], *q; int *key, len, m, i, j=0; //clrscr(); printf("********Permutation Cipher********\\nPlease input primal sentence: "); gets(c); strcpy(c, strupr(c)); len = strlen(c); for(i=0; i if(c[i]<65||c[i]>90) { for(j=i; j len--; } } c[len] = '\\0'; printf("Input the length of the key: "); scanf("%d", &m); //key = (int)new(m*sizeof(int)); //q = (int)new(len*sizeof(int)); printf("Input the key: "); for(i=0; i scanf("%d", key+i); key[i]--; } getchar(); for(i=0; i j = (i/m)*m; q[i] = c[*(key+i%m)+j]; } q[i] = '\\0'; printf("Result is: %s\\n", q); for(i=0, j=0; i j = (i/m)*m; c[*(key+i%m)+j] = q[i]+32; } c[len] = '\\0'; printf("After translated the sentence,we can see the primal sentence as follow:\\n%s\\n", c); printf("Press any key to return..."); free(key); free(q); getch(); } int main(int argc, char* argv[]) { char i = '0'; //clrscr(); while(i!='5') { //clrscr(); printf("********Press 1~5 to choose:********\\n"); printf("1. Shift Cipher\\n2. Affine Cipher\\n3. Vigenere Cipher\\n4. Permutation Cipher\\n5. Exit\\n"); i = getch(); if(i=='1') Shift(); else if(i=='2') Affine(); else if(i=='3') Vigenere(); else if(i=='4') Permutation(); else if(i=='5') break; } return 0; } 7 按运行按钮，看编译运行结果，如图1-1所示： 图1-1 加密运行界面 8 选择3，按如1-2所示，输入明文和密钥，调试输出对应加密密文。 图1-2 选择维吉尼亚加密方法 ●换位密码 1 启动VC++6.0。 2 新建Win32 Console Application。 3 在Project Name和Locate位置填上工程名string和保存位置（自选）。 4 按OK按钮。选An simple Project。 5 按Finish按钮。 6 在string.cpp中添加如下代码： #include "stdafx.h" #include #include int main(int argc, char * argv[])//注释加密程序，解密程序类同，不重复 { char a[80]; int k,i; printf("请输入移位值K和明文（小写字母，以'#'结束）：\n"); scanf("%d\\n",&k);//输入密码K if(k>26)//移位超出26时，相当于重复循环 k=k%26; for(i=0;i<80;i++) { scanf("%c",&a[i]);//输入明文 if(a[i]=='#')break; } printf("密文如下：\n"); for(i=0;a[i]!='#';i++) { if(a[i]<97||a[i]>122) { printf("移位值K格式出错或明文输入错误，无法显示密文！退出！\n"); return 0; } } for(i=0;a[i]!='#';i++) { if(k>0) { a[i]=a[i]-32; if(k>90-a[i]) a[i]=65+(k-(90-a[i]))-1; else a[i]=a[i]+k;//非循环情况是转换成大写后，加上移位密码即可 } else { k=-k; if(k>26)//移位超出26时，相当于重复循环 k=k%26; a[i]=a[i]-32; if(k>a[i]-65) a[i]=90-(k-(a[i]-65))-1; else a[i]=a[i]-k; k=-k; } printf("%c",a[i]); } printf("\\n"); k=0; printf("请输入移位值K和密文（大写字母，以'#'结束）：\n"); scanf("%d\\n",&k); if(k>26) k=k%26; for(i=0;i<80;i++) { scanf("%c",&a[i]); if(a[i]=='#')break; } printf("明文如下：\n"); for(i=0;a[i]!='#';i++) { if(a[i]<65||a[i]>90) { printf("移位值K格式出错或密文输入错误，无法显示明文！退出！\n"); return 0; } } for(i=0;a[i]!='#';i++) { if(k>0) { a[i]=a[i]+32; if(k>a[i]-97) a[i]=122-(k-(a[i]-97))+1; else a[i]=a[i]-k; } else { k=-k; if(k>26) k=k%26; a[i]=a[i]+32; if(k>122-a[i]) a[i]=97+(k-(122-a[i]))+1; else a[i]=a[i]+k; k=-k; } printf("%c",a[i]); } printf("\\n"); getch(); return 0; } 换位密码运行结果如图1-3所示： 加密——移位k=2,明文：abc 解密——移位K=2，密文CDE 图1-3 换位密码运行结果 ●DES加密算法——S盒替代 注意红色字体代码 步骤同多表替代密码。工程名为DESLxp,在DES.cpp中添加如下代码： #include "stdafx.h" #include "DESlxp.h" #include "DES.h" #ifdef _DEBUG #undef THIS_FILE static char THIS_FILE[]=__FILE__; #define new DEBUG_NEW #endif //////////////////////////////////////////////////////////////////// Construction/Destruction //////////////////////////////////////////////////////////////////DES::DES() { } DES::~DES() { } // initial permutation IP const static char IP_Table[] = { 58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, , 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 }; // final permutation IP^-1 const static char IPR_Table[] = { 40, 8, 48, 16, 56, 24, , 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 }; // expansion operation matrix static const char E_Table[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, 32, 1 }; // 32-bit permutation function P used on the output of the S-boxes const static char P_Table[32] = { 16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25 }; // permuted choice table (key) const static char PC1_Table[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 }; // permuted choice key (table) const static char PC2_Table[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}; // number left rotations of pc1 const static char LOOP_Table[16] = { 1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1}; // The (in)famous S-boxes const static 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, 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 }; //////////////////////////////////////////////////////////////////typedef bool (*PSubKey)[16][48]; //////////////////////////////////////////////////////////////////static void SDES(char Out[8], char In[8], const PSubKey pSubKey, bool Type);//标准DES加/解密 static void SetKey(const char* Key, int len);// 设置密钥 static void SetSubKey(PSubKey pSubKey, const char Key[8]);// 设置子密钥 static void F_func(bool In[32], const bool Ki[48]);// f 函数 static void S_func(bool Out[32], const bool In[48]);// S 盒代替 static void Transform(bool *Out, bool *In, const char *Table, int len);// 变换 static void Xor(bool *InA, const bool *InB, int len);// 异或 static void RotateL(bool *In, int len, int loop);// 循环左移 static void ByteToBit(bool *Out, const char *In, int bits);// 字节组转换成位组 static void BitToByte(char *Out, const bool *In, int bits);// 位组转换成字节组 //////////////////////////////////////////////////////////////////static bool SubKey[2][16][48];// 16圈子密钥 static bool Is3DES;// 3次DES标志 static char Tmp[256], deskey[16]; ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Code starts from Line 130 //////////////////////////////////////////////////////////////////void SetKey(const char* Key, int len) { memset(deskey, 0, 16); memcpy(deskey, Key, len>16?16:len); SetSubKey(&SubKey[0], &deskey[0]); Is3DES = len>8 ? (SetSubKey(&SubKey[1], &deskey[8]), true) : false; } void SDES(char Out[8], char In[8], const PSubKey pSubKey, bool Type) { static bool M[], tmp[32], *Li=&M[0], *Ri=&M[32]; ByteToBit(M, In, ); Transform(M, M, IP_Table, ); if( Type == ENCRYPT ){ for(int i=0; i<16; ++i) { memcpy(tmp, Ri, 32); F_func(Ri, (*pSubKey)[i]); Xor(Ri, Li, 32); memcpy(Li, tmp, 32); } }else{ for(int i=15; i>=0; --i) { memcpy(tmp, Li, 32); F_func(Li, (*pSubKey)[i]); Xor(Li, Ri, 32); memcpy(Ri, tmp, 32); } } Transform(M, M, IPR_Table, ); BitToByte(Out, M, ); } void SetSubKey(PSubKey pSubKey, const char Key[8]) { static bool K[], *KL=&K[0], *KR=&K[28]; ByteToBit(K, Key, ); Transform(K, K, PC1_Table, 56); for(int i=0; i<16; ++i) { RotateL(KL, 28, LOOP_Table[i]); RotateL(KR, 28, LOOP_Table[i]); Transform((*pSubKey)[i], K, PC2_Table, 48); } } void F_func(bool In[32], const bool Ki[48]) { static bool MR[48]; Transform(MR, In, E_Table, 48); Xor(MR, Ki, 48); S_func(In, MR); Transform(In, In, P_Table, 32); } void S_func(bool Out[32], const bool In[48]) { for(char i=0,j,k; i<8; ++i,In+=6,Out+=4) { j = (In[0]<<1) + In[5]; k = (In[1]<<3) + (In[2]<<2) + (In[3]<<1) + In[4]; ByteToBit(Out, &S_Box[i][j][k], 4); } } void Transform(bool *Out, bool *In, const char *Table, int len) { for(int i=0; i memcpy(Out, Tmp, len); } void Xor(bool *InA, const bool *InB, int len) { for(int i=0; i } void RotateL(bool *In, int len, int loop) { memcpy(Tmp, In, loop); memcpy(In, In+loop, len-loop); memcpy(In+len-loop, Tmp, loop); } void ByteToBit(bool *Out, const char *In, int bits) { for(int i=0; i } void BitToByte(char *Out, const bool *In, int bits) { memset(Out, 0, bits>>3); for(int i=0; i } bool DES::Des_Go(char *Out, char *In, long datalen, const char *Key, int keylen, bool Type) { if( !( Out && In && Key && (datalen=(datalen+7)&0xfffffff8) ) ) return false; SetKey(Key, keylen); if( !Is3DES ) { // 1次DES for(long i=0,j=datalen>>3; i } else{ // 3次DES 加密:加(key0)-解(key1)-加(key0) 解密::解(key0)-加(key1)-解(key0) for(long i=0,j=datalen>>3; i SDES(Out, Out, &SubKey[1], !Type); SDES(Out, Out, &SubKey[0], Type); } } return true; } DES运行结果如图1-4所示：（提示：本次实验解密以8位明文进行加密为例） 图1-4 DES加密运行结果 五 、思考题 1、DES算法主要有哪几部分？ 2、DES加密算法中S盒替代原理是什么？ 3、维吉尼亚多表替代算法原理是什么？ 4、写出采用维吉尼亚算法加密解密实验结果样例。（不允许跟实验指导书重复） 5、写出换位密码加密解密实验结果样例。（不允许跟实验指导书重复）
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