下面程序用异或 *** 作对文件进行加密和解密
/******************设计思路******************/
//根据用户输入的加密/机密密码，
//每次都拿原文灶困滚件和密码等长度的一个字符串和密码
//对应元素异或进行加密/解密
//另外因为是用异或方法，所以加密和解密就是同一个程序
//即按照同样的加密即是对文件的解密
#include
#include
#include
#include
#include
charfilename[256]//原文件
charpassword[256]//加密/解密密码
constcharfilenametemp[]="temp15435255435325432543.temp"//加密/解密中间文件
voidinputpass(char*pass)//密码输入以"******"显示
voidmain(){
FILE*fp//加密/解密的文件
FILE*fptemp//加密/解密过程临时文件
intpwdlen//密码长度
inti=0//计数器
charch=0//读入的字符
printf("请输入要加密/解密的文件名(全路径名):\n")
gets(filename)
if((fp=fopen(filename,"rb"))==NULL){
printf("找不到文件%s\n",filename)
exit(1)
}//if
printf("请输入要加密/解密的密码:\n")
inputpass(password)
pwdlen=strlen(password)
if(pwdlen==0){
printf("密码不能为空，加密/解密失败\n")
exit(1)
}//if
fptemp=fopen(filenametemp,"wb")//打开中间文件
while(1){
ch=fgetc(fp)//从原文件读入一个字符
if(feof(fp)){//已经读到文件尾
break//退出循环
}
ch^=password[i++]//对原字符和密码进行异或 *** 作
fputc(ch,fptemp)//将异或结果写入中间文件
if(i==pwdlen){//使得原文件每和密码长度相同的固定长度异或加密
i=0
}
}//while
fclose(fp)//关闭打开原文件
fclose(fptemp)//关闭打开中间文件
remove(filename)//删除原文件
rename(filenametemp,filename)//将隐余中间文件重命名为原文件
printf("加密/解密成功\n")//至此加密/解密成功
}
//密码输入以"******"显示
voidinputpass(char*pass){
inti=0
charc
while(isprint(c=getch())){
pass[i++]=c
//printf("*")
}
pass[i]='\0'
printf("\n")
}
C语言灶培设计一个简单的加密解密程序如下：加密程银嫌序代码：
#include<stdio.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>=32&&c<=126)
{
c=c-32
c=126-c
}
if(c!=-1)
fprintf(fp2,"%c",c)
}
while(c!=-1)
}
解密程序代码：
#include<stdio.h>
#include<string.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>=32&&c<=126)
{
c=126-c
c=32+c
}
if(c!=-1)
fprintf(fp2,"%c",c)
}
while(c!=-1)
}
else
{
printf("锋辩手验证码错误！请重新输入:\n")
scanf("%s",filename)
}
}
根据你的需要，修改了之前的代码。
#include <stdio.h>#include <string.h>
#include <stdlib.h>
#include <time.h>
const unsigned int MAX_KEY_LENGTH = 1000
int encode(char const *datafile, char const *keyfill)
int decode(char const *datafile, char const *keyfile)
int loadKey(char const *keyfile, int *keys, unsigned int size)
int saveKey(char const *keyfile, int *keys, unsigned int size)
int generateKey(int *keys, unsigned int size)
int main(int argc, char const *argv[])
{
char datafile[] = "encrypted.txt"
char keyfile[] = "key.txt"
int retcode, choice, loop = 1
char ch[5] = {'\0'}
while(1)
{
printf("1. Encryption.\n")
printf("2. Decryption.\n")
printf("3. Exit.\n")
printf("Selection (1,2,3):")
fgets(ch, sizeof(ch), stdin)
sscanf(ch, "%d", &choice)
switch(choice)
{
case 1:
retcode = encode(datafile, keyfile)
if (retcode 扒源!= 0) printf("error, %d\0", retcode)
break
case 2:
retcode = decode(datafile, keyfile)
if (retcode != 0) printf("error, %d\0", retcode)
break
case 3:
loop = 0
break
default:
纤陪
break
}
毁此蠢 if (0 == loop) break
}
return 0
}
int generateKey(int *keys, unsigned int size)
{
char str[]="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz,./\"'<>?"
size_t str_len = sizeof(str)/sizeof(str[0])
int i
srand(time(NULL))
for (i = 0 i < size ++i)
keys[i] = str[rand() % str_len]
return 0
}
int loadKey(char const *keyfile, int *keys, unsigned int size)
{
int i = 0
FILE *pfile
int retcode = 0
pfile = fopen(keyfile, "r")
if (pfile == NULL) return -1
while ( !feof(pfile) ) {
if (i < size)
fscanf(pfile, "%d ", &keys[i++])
else
break
}
fclose(pfile)
return i
}
int saveKey(char const *keyfile, int *keys, unsigned int size)
{
FILE *pfile
int i
pfile = fopen(keyfile, "w")
if (pfile == NULL) return -1
for(i = 0 i < size ++i) {
fprintf(pfile, "%d ", keys[i])
}
fclose(pfile)
return 0
}
int encode(char const *datafile, char const *keyfile)
{
char original[MAX_KEY_LENGTH] = {'\0'}
char encrypted[MAX_KEY_LENGTH] = {'\0'}
int i, size
int keys[MAX_KEY_LENGTH]
FILE *pdatafile, *pkeyfile
pkeyfile = fopen(keyfile, "w")
if (NULL == pkeyfile) return -1
fclose(pkeyfile)
puts(" input message:")
gets(original)
size = strlen(original)
if (0 != generateKey(keys, size)) return -2
if (0 != saveKey(keyfile, keys, size) ) return -3
pdatafile = fopen(datafile, "w")
if (NULL == pdatafile) return -4
for (i = 0 i < size ++i) {
encrypted[i] = original[i] + keys[i]
fputc(encrypted[i], pdatafile)
fputc(encrypted[i], stdout)
}
printf("\n")
fclose(pdatafile)
return 0
}
int decode(char const *datafile, char const *keyfile)
{
FILE *pdatafile, *pkeyfile
int keys[MAX_KEY_LENGTH] = {0}
char original[MAX_KEY_LENGTH] = {'\0'}
char encrypted[MAX_KEY_LENGTH] = {'\0'}
int i, size
pkeyfile = fopen(keyfile, "r")
if (NULL == pkeyfile) return -1
fclose(pkeyfile)
pdatafile = fopen(datafile, "r")
if (NULL == pdatafile) return -2
fscanf(pdatafile,"%s",encrypted)
fclose(pdatafile)
size = loadKey(keyfile, keys, MAX_KEY_LENGTH)
if (size < 1) return -3
for (i = 0 i < strlen(encrypted) ++i) {
original[i] = encrypted[i]-keys[i]
fputc(original[i], stdout)
}
printf("\n")
return 0
}
运行结果：
1. Encryption.
2. Decryption.
3. Exit.
Selection (1,2,3):1
input message:
this is A test!
╓┐»╞Lñ╗ù|t▄╬╢╒è
1. Encryption.
2. Decryption.
3. Exit.
Selection (1,2,3):2
this is A test!
1. Encryption.
2. Decryption.
3. Exit.
Selection (1,2,3):3
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