下面程序用异或操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操作
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")
}
main.cpp#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "md5.c"
int main(int argc, char* argv[])
{
int i
unsigned char encrypt[] = "admin"//21232f297a57a5a743894a0e4a801fc3
unsigned char decrypt[16]
MD5_CTX md5
MD5Init(&md5)
MD5Update(&md5, encrypt, strlen((char*)encrypt))
MD5Final(&md5, decrypt)
printf("加密前:%s\n加密后:", encrypt)
for (i = 0i <16i++)
{
printf("%02x", decrypt[i])
}
getchar()
return 0
}
md5.c
#include <memory.h>
#include "md5.h"
unsigned char PADDING[] = { 0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 }
void MD5Init(MD5_CTX* context)
{
context->count[0] = 0
context->count[1] = 0
context->state[0] = 0x67452301
context->state[1] = 0xEFCDAB89
context->state[2] = 0x98BADCFE
context->state[3] = 0x10325476
}
void MD5Update(MD5_CTX* context, unsigned char* input, unsigned int inputlen)
{
unsigned int i = 0, index = 0, partlen = 0
index = (context->count[0] >>3) &0x3F
partlen = 64 - index
context->count[0] += inputlen <<3
if (context->count[0] <(inputlen <<3))
context->count[1]++
context->count[1] += inputlen >>29
if (inputlen >= partlen)
{
memcpy(&context->buffer[index], input, partlen)
MD5Transform(context->state, context->buffer)
for (i = partleni + 64 <= inputleni += 64)
MD5Transform(context->state, &input[i])
index = 0
}
else
{
i = 0
}
memcpy(&context->buffer[index], &input[i], inputlen - i)
}
void MD5Final(MD5_CTX* context, unsigned char digest[16])
{
unsigned int index = 0, padlen = 0
unsigned char bits[8]
index = (context->count[0] >>3) &0x3F
padlen = (index <56) ? (56 - index) : (120 - index)
MD5Encode(bits, context->count, 8)
MD5Update(context, PADDING, padlen)
MD5Update(context, bits, 8)
MD5Encode(digest, context->state, 16)
}
void MD5Encode(unsigned char* output, unsigned int* input, unsigned int len)
{
unsigned int i = 0, j = 0
while (j <len)
{
output[j] = input[i] &0xFF
output[j + 1] = (input[i] >>8) &0xFF
output[j + 2] = (input[i] >>16) &0xFF
output[j + 3] = (input[i] >>24) &0xFF
i++
j += 4
}
}
void MD5Decode(unsigned int* output, unsigned char* input, unsigned int len)
{
unsigned int i = 0, j = 0
while (j <len)
{
output[i] = (input[j]) |
(input[j + 1] <<8) |
(input[j + 2] <<16) |
(input[j + 3] <<24)
i++
j += 4
}
}
void MD5Transform(unsigned int state[4], unsigned char block[64])
{
unsigned int a = state[0]
unsigned int b = state[1]
unsigned int c = state[2]
unsigned int d = state[3]
unsigned int x[64]
MD5Decode(x, block, 64)
FF(a, b, c, d, x[0], 7, 0xd76aa478)/* 1 */
FF(d, a, b, c, x[1], 12, 0xe8c7b756)/* 2 */
FF(c, d, a, b, x[2], 17, 0x242070db)/* 3 */
FF(b, c, d, a, x[3], 22, 0xc1bdceee)/* 4 */
FF(a, b, c, d, x[4], 7, 0xf57c0faf)/* 5 */
FF(d, a, b, c, x[5], 12, 0x4787c62a)/* 6 */
FF(c, d, a, b, x[6], 17, 0xa8304613)/* 7 */
FF(b, c, d, a, x[7], 22, 0xfd469501)/* 8 */
FF(a, b, c, d, x[8], 7, 0x698098d8)/* 9 */
FF(d, a, b, c, x[9], 12, 0x8b44f7af)/* 10 */
FF(c, d, a, b, x[10], 17, 0xffff5bb1)/* 11 */
FF(b, c, d, a, x[11], 22, 0x895cd7be)/* 12 */
FF(a, b, c, d, x[12], 7, 0x6b901122)/* 13 */
FF(d, a, b, c, x[13], 12, 0xfd987193)/* 14 */
FF(c, d, a, b, x[14], 17, 0xa679438e)/* 15 */
FF(b, c, d, a, x[15], 22, 0x49b40821)/* 16 */
/* Round 2 */
GG(a, b, c, d, x[1], 5, 0xf61e2562)/* 17 */
GG(d, a, b, c, x[6], 9, 0xc040b340)/* 18 */
GG(c, d, a, b, x[11], 14, 0x265e5a51)/* 19 */
GG(b, c, d, a, x[0], 20, 0xe9b6c7aa)/* 20 */
GG(a, b, c, d, x[5], 5, 0xd62f105d)/* 21 */
GG(d, a, b, c, x[10], 9, 0x2441453)/* 22 */
GG(c, d, a, b, x[15], 14, 0xd8a1e681)/* 23 */
GG(b, c, d, a, x[4], 20, 0xe7d3fbc8)/* 24 */
GG(a, b, c, d, x[9], 5, 0x21e1cde6)/* 25 */
GG(d, a, b, c, x[14], 9, 0xc33707d6)/* 26 */
GG(c, d, a, b, x[3], 14, 0xf4d50d87)/* 27 */
GG(b, c, d, a, x[8], 20, 0x455a14ed)/* 28 */
GG(a, b, c, d, x[13], 5, 0xa9e3e905)/* 29 */
GG(d, a, b, c, x[2], 9, 0xfcefa3f8)/* 30 */
GG(c, d, a, b, x[7], 14, 0x676f02d9)/* 31 */
GG(b, c, d, a, x[12], 20, 0x8d2a4c8a)/* 32 */
/* Round 3 */
HH(a, b, c, d, x[5], 4, 0xfffa3942)/* 33 */
HH(d, a, b, c, x[8], 11, 0x8771f681)/* 34 */
HH(c, d, a, b, x[11], 16, 0x6d9d6122)/* 35 */
HH(b, c, d, a, x[14], 23, 0xfde5380c)/* 36 */
HH(a, b, c, d, x[1], 4, 0xa4beea44)/* 37 */
HH(d, a, b, c, x[4], 11, 0x4bdecfa9)/* 38 */
HH(c, d, a, b, x[7], 16, 0xf6bb4b60)/* 39 */
HH(b, c, d, a, x[10], 23, 0xbebfbc70)/* 40 */
HH(a, b, c, d, x[13], 4, 0x289b7ec6)/* 41 */
HH(d, a, b, c, x[0], 11, 0xeaa127fa)/* 42 */
HH(c, d, a, b, x[3], 16, 0xd4ef3085)/* 43 */
HH(b, c, d, a, x[6], 23, 0x4881d05)/* 44 */
HH(a, b, c, d, x[9], 4, 0xd9d4d039)/* 45 */
HH(d, a, b, c, x[12], 11, 0xe6db99e5)/* 46 */
HH(c, d, a, b, x[15], 16, 0x1fa27cf8)/* 47 */
HH(b, c, d, a, x[2], 23, 0xc4ac5665)/* 48 */
/* Round 4 */
II(a, b, c, d, x[0], 6, 0xf4292244)/* 49 */
II(d, a, b, c, x[7], 10, 0x432aff97)/* 50 */
II(c, d, a, b, x[14], 15, 0xab9423a7)/* 51 */
II(b, c, d, a, x[5], 21, 0xfc93a039)/* 52 */
II(a, b, c, d, x[12], 6, 0x655b59c3)/* 53 */
II(d, a, b, c, x[3], 10, 0x8f0ccc92)/* 54 */
II(c, d, a, b, x[10], 15, 0xffeff47d)/* 55 */
II(b, c, d, a, x[1], 21, 0x85845dd1)/* 56 */
II(a, b, c, d, x[8], 6, 0x6fa87e4f)/* 57 */
II(d, a, b, c, x[15], 10, 0xfe2ce6e0)/* 58 */
II(c, d, a, b, x[6], 15, 0xa3014314)/* 59 */
II(b, c, d, a, x[13], 21, 0x4e0811a1)/* 60 */
II(a, b, c, d, x[4], 6, 0xf7537e82)/* 61 */
II(d, a, b, c, x[11], 10, 0xbd3af235)/* 62 */
II(c, d, a, b, x[2], 15, 0x2ad7d2bb)/* 63 */
II(b, c, d, a, x[9], 21, 0xeb86d391)/* 64 */
state[0] += a
state[1] += b
state[2] += c
state[3] += d
}
md5.h
#ifndef MD5_H
#define MD5_H
typedef struct
{
unsigned int count[2]
unsigned int state[4]
unsigned char buffer[64]
}MD5_CTX
#define F(x,y,z) ((x &y) | (~x &z))
#define G(x,y,z) ((x &z) | (y &~z))
#define H(x,y,z) (x^y^z)
#define I(x,y,z) (y ^ (x | ~z))
#define ROTATE_LEFT(x,n) ((x <<n) | (x >>(32-n)))
#define FF(a,b,c,d,x,s,ac) \
{ \
a += F(b,c,d) + x + ac\
a = ROTATE_LEFT(a,s)\
a += b\
}
#define GG(a,b,c,d,x,s,ac) \
{ \
a += G(b,c,d) + x + ac\
a = ROTATE_LEFT(a,s)\
a += b\
}
#define HH(a,b,c,d,x,s,ac) \
{ \
a += H(b,c,d) + x + ac\
a = ROTATE_LEFT(a,s)\
a += b\
}
#define II(a,b,c,d,x,s,ac) \
{ \
a += I(b,c,d) + x + ac\
a = ROTATE_LEFT(a,s)\
a += b\
}
void MD5Init(MD5_CTX* context)
void MD5Update(MD5_CTX* context, unsigned char* input, unsigned int inputlen)
void MD5Final(MD5_CTX* context, unsigned char digest[16])
void MD5Transform(unsigned int state[4], unsigned char block[64])
void MD5Encode(unsigned char* output, unsigned int* input, unsigned int len)
void MD5Decode(unsigned int* output, unsigned char* input, unsigned int len)
#endif
c语言文件加密和解密方法如下：
1、首先打开VC++6.0；
2、选择文件，新建；
3、选择C++ source file 新建一个空白文档；
4、声明头文件
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
首先写个加密函数，算法就是简介里说的
void EncryptFile(FILE *sfp,FILE *dfp,char pwd){
char ch
if(sfp==0||dfp==0)
{
printf("ERROR!\n")
return
}
while((ch=fgetc(sfp))!=EOF)
{
if((ch>='a')&&(ch<='z'))
{
ch=(ch-'a'+1)%26+'a'
ch=ch^pwd
}
if((ch>='A')&&(ch<='Z'))
{
ch=(ch-'A'+1)%26+'A'
ch=ch^pwd
}
fputc(ch,dfp)
}
}
写解密子函数：与加密的过程相反
void DecryptFile(FILE *sfp,FILE *dfp,char pwd){
char ch
while((ch=fgetc(sfp))!=EOF)
{
if((ch>='a')&&(ch<='z'))
{
ch=ch^pwd
ch=(ch-'a'+25)%26+'a'
}
if((ch>='A')&&(ch<='Z'))
{
ch=ch^pwd
ch=(ch-'A'+25)%26+'A'
}
fputc(ch,dfp)
}
}
输出函数，输出文件内容
void OutputFile(FILE *fp)
{
char ch
while((ch=fgetc(fp))!=EOF)
putchar(ch)
}
主函数，主要调用这几个函数
int main()
{
/*用户输入的要加密的文件名*/
char sfilename[20]
/*用户输入加密后保存的文件名*/
char dfilename[20]
/*用来保存密码字符*/
char pwd
FILE *sfp,*dfp
printf("\nPlease input filename to be encrypted:\n")
/*得到要加密的文件名*/
gets(sfilename)
/*得到加密后你要的文件名*/
printf("input filename to save the encrypted file:\n")
gets(dfilename)
/*得到加密字符*/
printf("Please input your Password:\n")
//scanf("%c",&pwd)
pwd=getch()
/*屏幕以*来表示输入的加密字符*/
printf("*\n")
/*以只读方式打开要加密的文件*/
if((sfp=fopen(sfilename,"r"))==0)
{
printf("Can't open the file :%s\n",sfilename)
exit(0)
}
/*输出要加密的文件*/
printf("\nThe the text of file to be encrypted is:\n")
OutputFile(sfp)
/*建立加密后的文件*/
if((dfp=fopen(dfilename,"w+"))==0)
{
printf("Can't open or create the file :%s\n",dfilename)
//exit(0)
}
/*文件加密*/
fseek(sfp,0L,SEEK_SET)
EncryptFile(sfp,dfp,pwd)
printf("\n\nEncrypted the file successfully!\n")
/*输出加密后的文件*/
printf("\nAfter encrypting the text of file is:\n")
fseek(dfp,0L,SEEK_SET)
OutputFile(dfp)
fclose(sfp)
fclose(dfp)
getch()
return 0
}
