c语言实现MD5算法的项目实践
作者：hs977986979
MD5用于确保信息传输完整一致，是计算机广泛使用的杂凑算法之一，本文主要介绍了c语言实现MD5算法，具有一定的参考价值，感兴趣的可以了解一下
MD5介绍
1。 一种单向加密算法，即对明文加密，而不能通过密文得到明文。对原数据的任何改动，哪怕是1字节，得到的MD5值都有很大的区别。可以用公式表示：密文=Md5_calc(原文数据)；
应用场景
1.密码认证；
2.数据校验：
代码分析 （基于qt5.14.2）
md5.c
#include <string.h>
#include "md5.h"
#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 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);
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 = partlen;i+64 <= inputlen;i+=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);
FF(d, a, b, c, x[ 1], 12, 0xe8c7b756);
FF(c, d, a, b, x[ 2], 17, 0x242070db);
FF(b, c, d, a, x[ 3], 22, 0xc1bdceee);
FF(a, b, c, d, x[ 4], 7, 0xf57c0faf);
FF(d, a, b, c, x[ 5], 12, 0x4787c62a);
FF(c, d, a, b, x[ 6], 17, 0xa8304613);
FF(b, c, d, a, x[ 7], 22, 0xfd469501);
FF(a, b, c, d, x[ 8], 7, 0x698098d8);
FF(d, a, b, c, x[ 9], 12, 0x8b44f7af);
FF(c, d, a, b, x[10], 17, 0xffff5bb1);
FF(b, c, d, a, x[11], 22, 0x895cd7be);
FF(a, b, c, d, x[12], 7, 0x6b901122);
FF(d, a, b, c, x[13], 12, 0xfd987193);
FF(c, d, a, b, x[14], 17, 0xa679438e);
FF(b, c, d, a, x[15], 22, 0x49b40821);
GG(a, b, c, d, x[ 1], 5, 0xf61e2562);
GG(d, a, b, c, x[ 6], 9, 0xc040b340);
GG(c, d, a, b, x[11], 14, 0x265e5a51);
GG(b, c, d, a, x[ 0], 20, 0xe9b6c7aa);
GG(a, b, c, d, x[ 5], 5, 0xd62f105d);
GG(d, a, b, c, x[10], 9, 0x2441453);
GG(c, d, a, b, x[15], 14, 0xd8a1e681);
GG(b, c, d, a, x[ 4], 20, 0xe7d3fbc8);
GG(a, b, c, d, x[ 9], 5, 0x21e1cde6);
GG(d, a, b, c, x[14], 9, 0xc33707d6);
GG(c, d, a, b, x[ 3], 14, 0xf4d50d87);
GG(b, c, d, a, x[ 8], 20, 0x455a14ed);
GG(a, b, c, d, x[13], 5, 0xa9e3e905);
GG(d, a, b, c, x[ 2], 9, 0xfcefa3f8);
GG(c, d, a, b, x[ 7], 14, 0x676f02d9);
GG(b, c, d, a, x[12], 20, 0x8d2a4c8a);
HH(a, b, c, d, x[ 5], 4, 0xfffa3942);
HH(d, a, b, c, x[ 8], 11, 0x8771f681);
HH(c, d, a, b, x[11], 16, 0x6d9d6122);
HH(b, c, d, a, x[14], 23, 0xfde5380c);
HH(a, b, c, d, x[ 1], 4, 0xa4beea44);
HH(d, a, b, c, x[ 4], 11, 0x4bdecfa9);
HH(c, d, a, b, x[ 7], 16, 0xf6bb4b60);
HH(b, c, d, a, x[10], 23, 0xbebfbc70);
HH(a, b, c, d, x[13], 4, 0x289b7ec6);
HH(d, a, b, c, x[ 0], 11, 0xeaa127fa);
HH(c, d, a, b, x[ 3], 16, 0xd4ef3085);
HH(b, c, d, a, x[ 6], 23, 0x4881d05);
HH(a, b, c, d, x[ 9], 4, 0xd9d4d039);
HH(d, a, b, c, x[12], 11, 0xe6db99e5);
HH(c, d, a, b, x[15], 16, 0x1fa27cf8);
HH(b, c, d, a, x[ 2], 23, 0xc4ac5665);
II(a, b, c, d, x[ 0], 6, 0xf4292244);
II(d, a, b, c, x[ 7], 10, 0x432aff97);
II(c, d, a, b, x[14], 15, 0xab9423a7);
II(b, c, d, a, x[ 5], 21, 0xfc93a039);
II(a, b, c, d, x[12], 6, 0x655b59c3);
II(d, a, b, c, x[ 3], 10, 0x8f0ccc92);
II(c, d, a, b, x[10], 15, 0xffeff47d);
II(b, c, d, a, x[ 1], 21, 0x85845dd1);
II(a, b, c, d, x[ 8], 6, 0x6fa87e4f);
II(d, a, b, c, x[15], 10, 0xfe2ce6e0);
II(c, d, a, b, x[ 6], 15, 0xa3014314);
II(b, c, d, a, x[13], 21, 0x4e0811a1);
II(a, b, c, d, x[ 4], 6, 0xf7537e82);
II(d, a, b, c, x[11], 10, 0xbd3af235);
II(c, d, a, b, x[ 2], 15, 0x2ad7d2bb);
II(b, c, d, a, x[ 9], 21, 0xeb86d391);
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;
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]);
#endifmain.c
#include <QCoreApplication>
extern "C"{ //添加头文件
#include "md5.h"
}
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
int i, n;
bool isfile = false;
unsigned char decrypt[16];
MD5_CTX md5;
if(argc > 1 && strlen(argv[1]) == 2 && !memcmp(argv[1], "-f", 2)) {
isfile = true;
}
if(argc == 1 || (argc == 2 && isfile)) {
fprintf(stderr, "usage:\n %s -f file ...\n %s string ...\n", argv[0], argv[0]);
return 1;
}
if(isfile) {
FILE *fp;
for(n=2; n<argc; n++) {
fp = fopen(argv[n], "rb");
if(fp == NULL) {
fprintf(stderr, "File %s not exists, errno = %d, error = %s\n", argv[n], errno, strerror(errno));
continue;
}
MD5Init(&md5);
do {
unsigned char encrypt[1024];
while(!feof(fp)) {
MD5Update(&md5, encrypt, fread(encrypt, 1, sizeof(encrypt), fp));
}
fclose(fp);
} while(0);
MD5Final(&md5, decrypt);
for(i=0; i<16; i++) {
printf("%02x", decrypt[i]); //02x前需要加上 %
}
printf(" %s\n", argv[n]);
}
} else {
for(n=1; n<argc; n++) {
MD5Init(&md5);
MD5Update(&md5,(unsigned char*) argv[n], strlen(argv[n]));
MD5Final(&md5, decrypt);
for(i=0; i<16; i++) {
printf("%02x", decrypt[i]); //02x前需要加上 %
}
printf(" %s\n", argv[n]);
}
}
return a.exec();
}测试记录 源码打包（windeployqt.exe工具），得到MD5.exe
运行测试，创建一个test.txt文件，打开文件写入：123，保存关闭，运行如下测试命令：MD5.exe -f test.txt 得到密文：202cb962ac59075b964b07152d234b70
测试准确性，利用在线工具，输入：123得到相同的密文，验证成功。
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