四种加密解密算法的源代码：移位密码、仿射密码、维吉尼亚密码以及置换密码#include <stdio.h>#include <conio.h>#include <string.h>#include <malloc.h>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<length; i++){if(c[i]>96&&c[i]<123)c[i] = (c[i]+key-97)%26+65;else if(c[i]>64&&c[i]<91)c[i] = (c[i]+key-65)%26+65;}printf("Result is: %s\n", c);for(i=0; i<length; i++){if(c[i]>64&&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 gcd(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(gcd(ka,26)!=1){printf("The value of the key is error!\nPress any key to return..."); return;}for(i=0; i<length; i++){if(c[i]>96&&c[i]<123)c[i] = (ka*(c[i]-97)+kb)%26+65;else if(c[i]>64&&c[i]<91)c[i] = (ka*(c[i]-65)+kb)%26+65;printf("Result is: %s\n", c);for(i=0; i<length; i++){if(c[i]>64&&c[i]<91){tmp = Ni(ka,26)*((c[i]-65)-kb);if(tmp<0)c[i] = tmp%26+26+97;elsec[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<lenc; i++){j = j%lenk;if(c[i]>64&&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<lenc; i++)j = j%lenk;if(c[i]>64&&c[i]<91){tmp = c[i]-65-(key[j]-65);if(tmp>=0)c[i] = tmp%26+97;elsec[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<len; i++){if(c[i]<65||c[i]>90){for(j=i; j<len-1; j++)c[j] = c[j+1];len--;}}c[len] = '\0';printf("Input the length of the key: ");scanf("%d", &m);key = (int)malloc(m*sizeof(int));q = (int)malloc(len*sizeof(int));printf("Input the key: ");for(i=0; i<m; i++)scanf("%d", key+i);key[i]--;}getchar();for(i=0; i<len; 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<len; 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();}void main(){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;}}。