c语言编写加密程序

#include <stdio.h>

#include <string.h>

#include "global.h"

#include "md5.h"

#define S11 7

#define S12 12

#define S13 17

#define S14 22

#define S21 5

#define S22 9

#define S23 14

#define S24 20

#define S31 4

#define S32 11

#define S33 16

#define S34 23

#define S41 6

#define S42 10

#define S43 15

#define S44 21

static void MD5Transform PROTO_LIST ((UINT4 [4], unsigned char

[64]))

static void Encode PROTO_LIST

((unsigned char *, UINT4 *, unsigned int))

static void Decode PROTO_LIST

((UINT4 *, unsigned char *, unsigned int))

static void MD5_memcpy PROTO_LIST ((POINTER, POINTER, unsigned

int))

static void MD5_memset PROTO_LIST ((POINTER, int, unsigned int))

static unsigned char PADDING[64] = {

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

}

#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) + (UINT4)(ac)(a) = ROTATE_LEFT ((a), (s))(a) += (b)}

#define GG(a, b, c, d, x, s, ac) { \

(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac)\

(a) = ROTATE_LEFT ((a), (s))\

(a) += (b)\

}

#define HH(a, b, c, d, x, s, ac) { \

(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac)\

(a) = ROTATE_LEFT ((a), (s))\

(a) += (b)\

}

#define II(a, b, c, d, x, s, ac) { \

(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac)\

(a) = ROTATE_LEFT ((a), (s))\

(a) += (b)\

}

void MD5Init (context)

MD5_CTX *context

{

context->count[0] = context->count[1] = 0

context->state[0] = 0x67452301

context->state[1] = 0xefcdab89

context->state[2] = 0x98badcfe

context->state[3] = 0x10325476

}

void MD5Update (context, input, inputLen)

MD5_CTX *context

unsigned char *input

unsigned int inputLen

{

unsigned int i, index, partLen

index = (unsigned int)((context->count[0] >>3) &0x3F)

if ((context->count[0] += ((UINT4)inputLen <<3))<((UINT4)inputLen <<3))

context->count[1]++

context->count[1] += ((UINT4)inputLen >>29)

partLen = 64 - index

if (inputLen >= partLen)

{

MD5_memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen)

MD5Transform (context->state, context->buffer)

for (i = partLeni + 63 <inputLeni += 64)

MD5Transform (context->state, &input[i])

index = 0

}

else

i = 0

MD5_memcpy((POINTER)&context->buffer[index], (POINTER)&input[i],inputLen-i)

}

void MD5Final (digest, context)

unsigned char digest[16]

MD5_CTX *context

{

unsigned char bits[8]

unsigned int index, padLen

Encode (bits, context->count, 8)

index = (unsigned int)((context->count[0] >>3) &0x3f)

padLen = (index <56) ? (56 - index) : (120 - index)

MD5Update (context, PADDING, padLen)

MD5Update (context, bits, 8)

Encode (digest, context->state, 16)

MD5_memset ((POINTER)context, 0, sizeof (*context))

}

static void MD5Transform (UINT4 state[4], unsigned char block[64])

{

UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16]

Decode (x, block, 64)

FF (a, b, c, d, x[ 0], S11, 0xd76aa478)/* 1 */

FF (d, a, b, c, x[ 1], S12, 0xe8c7b756)/* 2 */

FF (c, d, a, b, x[ 2], S13, 0x242070db)/* 3 */

FF (b, c, d, a, x[ 3], S14, 0xc1bdceee)/* 4 */

FF (a, b, c, d, x[ 4], S11, 0xf57c0faf)/* 5 */

FF (d, a, b, c, x[ 5], S12, 0x4787c62a)/* 6 */

FF (c, d, a, b, x[ 6], S13, 0xa8304613)/* 7 */

FF (b, c, d, a, x[ 7], S14, 0xfd469501)/* 8 */

FF (a, b, c, d, x[ 8], S11, 0x698098d8)/* 9 */

FF (d, a, b, c, x[ 9], S12, 0x8b44f7af)/* 10 */

FF (c, d, a, b, x[10], S13, 0xffff5bb1)/* 11 */

FF (b, c, d, a, x[11], S14, 0x895cd7be)/* 12 */

FF (a, b, c, d, x[12], S11, 0x6b901122)/* 13 */

FF (d, a, b, c, x[13], S12, 0xfd987193)/* 14 */

FF (c, d, a, b, x[14], S13, 0xa679438e)/* 15 */

FF (b, c, d, a, x[15], S14, 0x49b40821)/* 16 */

/* Round 2 */

GG (a, b, c, d, x[ 1], S21, 0xf61e2562)/* 17 */

GG (d, a, b, c, x[ 6], S22, 0xc040b340)/* 18 */

GG (c, d, a, b, x[11], S23, 0x265e5a51)/* 19 */

GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa)/* 20 */

GG (a, b, c, d, x[ 5], S21, 0xd62f105d)/* 21 */

GG (d, a, b, c, x[10], S22, 0x2441453)/* 22 */

GG (c, d, a, b, x[15], S23, 0xd8a1e681)/* 23 */

GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8)/* 24 */

GG (a, b, c, d, x[ 9], S21, 0x21e1cde6)/* 25 */

GG (d, a, b, c, x[14], S22, 0xc33707d6)/* 26 */

GG (c, d, a, b, x[ 3], S23, 0xf4d50d87)/* 27 */

GG (b, c, d, a, x[ 8], S24, 0x455a14ed)/* 28 */

GG (a, b, c, d, x[13], S21, 0xa9e3e905)/* 29 */

GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8)/* 30 */

GG (c, d, a, b, x[ 7], S23, 0x676f02d9)/* 31 */

GG (b, c, d, a, x[12], S24, 0x8d2a4c8a)/* 32 */

/* Round 3 */

HH (a, b, c, d, x[ 5], S31, 0xfffa3942)/* 33 */

HH (d, a, b, c, x[ 8], S32, 0x8771f681)/* 34 */

HH (c, d, a, b, x[11], S33, 0x6d9d6122)/* 35 */

HH (b, c, d, a, x[14], S34, 0xfde5380c)/* 36 */

HH (a, b, c, d, x[ 1], S31, 0xa4beea44)/* 37 */

HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9)/* 38 */

HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60)/* 39 */

HH (b, c, d, a, x[10], S34, 0xbebfbc70)/* 40 */

HH (a, b, c, d, x[13], S31, 0x289b7ec6)/* 41 */

HH (d, a, b, c, x[ 0], S32, 0xeaa127fa)/* 42 */

HH (c, d, a, b, x[ 3], S33, 0xd4ef3085)/* 43 */

HH (b, c, d, a, x[ 6], S34, 0x4881d05)/* 44 */

HH (a, b, c, d, x[ 9], S31, 0xd9d4d039)/* 45 */

HH (d, a, b, c, x[12], S32, 0xe6db99e5)/* 46 */

HH (c, d, a, b, x[15], S33, 0x1fa27cf8)/* 47 */

HH (b, c, d, a, x[ 2], S34, 0xc4ac5665)/* 48 */

/* Round 4 */

II (a, b, c, d, x[ 0], S41, 0xf4292244)/* 49 */

II (d, a, b, c, x[ 7], S42, 0x432aff97)/* 50 */

II (c, d, a, b, x[14], S43, 0xab9423a7)/* 51 */

II (b, c, d, a, x[ 5], S44, 0xfc93a039)/* 52 */

II (a, b, c, d, x[12], S41, 0x655b59c3)/* 53 */

II (d, a, b, c, x[ 3], S42, 0x8f0ccc92)/* 54 */

II (c, d, a, b, x[10], S43, 0xffeff47d)/* 55 */

II (b, c, d, a, x[ 1], S44, 0x85845dd1)/* 56 */

II (a, b, c, d, x[ 8], S41, 0x6fa87e4f)/* 57 */

II (d, a, b, c, x[15], S42, 0xfe2ce6e0)/* 58 */

II (c, d, a, b, x[ 6], S43, 0xa3014314)/* 59 */

II (b, c, d, a, x[13], S44, 0x4e0811a1)/* 60 */

II (a, b, c, d, x[ 4], S41, 0xf7537e82)/* 61 */

II (d, a, b, c, x[11], S42, 0xbd3af235)/* 62 */

II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb)/* 63 */

II (b, c, d, a, x[ 9], S44, 0xeb86d391)/* 64 */

state[0] += a

state[1] += b

state[2] += c

state[3] += d

MD5_memset ((POINTER)x, 0, sizeof (x))

}

static void Encode (output, input, len)

unsigned char *output

UINT4 *input

unsigned int len

{

unsigned int i, j

for (i = 0, j = 0j <leni++, j += 4)

{

output[j] = (unsigned char)(input[i] &0xff)

output[j+1] = (unsigned char)((input[i] >>8) &0xff)

output[j+2] = (unsigned char)((input[i] >>16) &0xff)

output[j+3] = (unsigned char)((input[i] >>24) &0xff)

}

}

static void Decode (output, input, len)

UINT4 *output

unsigned char *input

unsigned int len

{

unsigned int i, j

for (i = 0, j = 0j <leni++, j += 4)

output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) <<8) |(((UINT4)input[j+2]) <<16) | (((UINT4)input[j+3]) <<24)

}

static void MD5_memcpy (output, input, len)

POINTER output

POINTER input

unsigned int len

{

unsigned int i

for (i = 0i <leni++)

output[i] = input[i]

}

static void MD5_memset (output, value, len)

POINTER output

int value

unsigned int len

{

unsigned int i

for (i = 0i <leni++)

((char *)output)[i] = (char)value

}

#ifndef MD

#define MD 5

#endif

#define TEST_BLOCK_LEN 1000

#define TEST_BLOCK_COUNT 1000

static void MDString PROTO_LIST ((char *))

static void MDPrint PROTO_LIST ((unsigned char [16]))

#define MD_CTX MD5_CTX

#define MDInit MD5Init

#define MDUpdate MD5Update

#define MDFinal MD5Final

int main (int argc, char *argv[])

{

int i

if (argc >1)

{ MDString(argv[1])

return (0)

}

}

static void MDString (char *string)

{

MD_CTX context

unsigned char digest[16]

unsigned int len = strlen (string)

MDInit (&context)

MDUpdate (&context, string, len)

MDFinal (digest, &context)

printf ("MD%d (\"%s\") = ", MD, string)

MDPrint (digest)

printf ("\n")

}

static void MDPrint (unsigned char digest[16])

{

unsigned int i

for (i = 0i <16i++)

printf ("%02x", digest[i])

}

1、用一个字符数组来存密码

再用一个字符数组接收你的输入，然后用strcmp

来比较，如果返回0则密码是正确的

2、例程：

#include "stdio.h"

#include "string.h"

int main()

{

       char mima[100]="YuanShi888"

       char input[100]={0}

       printf("请输入密码:")

        gets(input)

       if(strcmp(mima,input)==0)

            printf("恭喜你，密码正确!\n")

       else

            printf("对不起，密码输入错误!\n")

  

}

这里采用加密函数是：

如果是数组，则不进行加密；

如果是字符，首先将a变成b,b变c,....依次类推，

然后再与加密字符异或

方法/步骤

首先打开VC++6.0

选择文件，新建

选择C++ source file 新建一个空白文档

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

}

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