C语言设计一个简单的加密解密程序如下：
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加密程序代码：
#includestdio.h
main()
{
char
c,filename[20];
FILE
*fp1,*fp2;
printf("请输入待加密的文件名:\n");
scanf("%s",filename);
fp1=fopen(filename,"r");
fp2=fopen("miwen.txt","w");
do
{
c=fgetc(fp1);
if(c=32c=126)
{
c=c-32;
c=126-c;
}
if(c!=-1)
fprintf(fp2,"%c",c);
}
while(c!=-1);
}
解密程序代码：
#includestdio.h
#includestring.h
main()
{
char
c,filename[20];
char
yanzhengma[20];
FILE
*fp1,*fp2;
printf("请输入待解密文件名:\n");
scanf("%s",filename);
printf("请输入验证码:\n");
scanf("%s",yanzhengma);
if(strcmp(yanzhengma,"shan")==0)
{
fp1=fopen(filename,"r");
fp2=fopen("yuanwen.txt","w");
do
{
c=fgetc(fp1);
if(c=32c=126)
{
c=126-c;
c=32+c;
}
if(c!=-1)
fprintf(fp2,"%c",c);
}
while(c!=-1);
}
else
{
printf("验证码错误！请重新输入:\n");
scanf("%s",filename);
}
}
C语言代码和运行结果如下：
输出符合示例，加解密均正确，望采纳~
附源码链接：字符串加解密
#include stdio.h
#include stdlib.h
#include string.h
const char *chlist = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
int encode_string(char* str, unsigned int length, char* stat) {
char s[103];
int i,j;
unsigned temp;
if(length = 0) return 1;
if(length 100) return 2;
str[length] = '\0';
strcpy(s,str);
while(strlen(s) % 3) strcat(s,"=");
for(i = 0,j = 0; s[i]; i += 3,j += 4) {
temp = s[i];
temp = (temp 8) + s[i + 1];
temp = (temp 8) + s[i + 2];
stat[j + 3] = chlist[temp 0X3F];
temp = 6;
stat[j + 2] = chlist[temp 0X3F];
temp = 6;
stat[j + 1] = chlist[temp 0X3F];
temp = 6;
stat[j + 0] = chlist[temp 0X3F];
}
stat[j] = '\0';
return 0;
}
int Index(char ch) {
int i;
for(i = 0; chlist[i]; ++i) {
if(chlist[i] == ch)
return i;
}
return -1;
}
void decode_string(char *s, char *t) {
unsigned temp;
int i,j,k,len = strlen(s);
if(len % 4) {
printf("无效数据。\n");
exit(2);
}
for(i = 0,j = 0; i = len; i += 4,j += 3) {
temp = 0;
for(k = 0; k 4; ++k)
temp = (temp 6) + Index(s[i + k]);
for(k = 2; k = 0; --k) {
t[j + k] = temp 0XFF;
temp = 8;
}
}
t[j + k] = '\0';
}
int main() {
char s[100] = "1a2a3s4dff5fj6u7M8B9P0O1U2";
char t[150],u[100];
printf("s = %s\n",s);
encode_string(s,strlen(s),t);
printf("t = %s\n",t);
decode_string(t,u);
printf("u = %s\n",u);
return 0;
}
