MD5算法的C语言实现

1

#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "md5.h"

#ifdef __cplusplus
extern "C" {
#endif

#define ROTATELEFT(value, bits) (((value) << (bits)) | ((value) >> (32 - (bits))))

#define TO_HEX_FMT_L "%02x"
#define TO_HEX_FMT_U "%02X"

/**
 * @desc: convert message and mes_bkp string into integer array and store them in w 
 */
static void md5_process_part1(uint32_t *w, const char *message, uint32_t *pos, uint32_t mes_len, const unsigned char *mes_bkp)
{
    uint32_t i; // used in for loop

    for(i = 0; i <= 15; i++)
    {
        int32_t count = 0;
        while(*pos < mes_len && count <= 24)
        {
            w[i] += (((uint32_t)message[*pos]) << count);
            (*pos)++;
            count += 8;
        }
        while(count <= 24)
        {
            w[i] += (((uint32_t)mes_bkp[*pos - mes_len]) << count);
            (*pos)++;
            count += 8;
        }
    }
}

/**
 * @desc: start encryption based on w
 */
static void md5_process_part2(uint32_t abcd[4], uint32_t *w, const uint32_t k[64], const uint32_t s[64])
{
    uint32_t i; // used in for loop

    uint32_t a = abcd[0];
    uint32_t b = abcd[1];
    uint32_t c = abcd[2];
    uint32_t d = abcd[3];
    uint32_t f = 0;
    uint32_t g = 0;

    for(i = 0; i < 64; i++)
    {
        if(i >= 0 && i <= 15)
        {
            f = (b & c) | ((~b) & d);
            g = i;
        }else if(i >= 16 && i <= 31)
        {
            f = (d & b) | ((~d) & c);
            g = (5 * i + 1) % 16;
        }else if(i >= 32 && i <= 47)
        {
            f = b ^ c ^ d;
            g = (3 * i + 5) % 16;
        }else if(i >= 48 && i <= 63)
        {
            f = c ^ (b | (~d));
            g = (7 * i) % 16;
        }
        uint32_t temp = d;
        d = c;
        c = b;
        b = ROTATELEFT((a + f + k[i] + w[g]), s[i]) + b;
        a = temp;
    }

    abcd[0] += a;
    abcd[1] += b;
    abcd[2] += c;
    abcd[3] += d;
}

/**
 * @desc: format the output, convert numbers to hexdecimal string and store them in result
 */
static void format_output(char *result, size_t size, uint32_t *abcd, uint32_t flag)
{
    uint32_t i; // used in for loop
    
    memset(result, 0, size);

    uint32_t ptr = 0;
    for(i = 0; i < 4; i++)
    {
        ptr += snprintf(result + ptr, size - ptr, (flag == 0)?TO_HEX_FMT_U:TO_HEX_FMT_L, (abcd[i] & 0x000000FF));
        ptr += snprintf(result + ptr, size - ptr, (flag == 0)?TO_HEX_FMT_U:TO_HEX_FMT_L, (abcd[i] & 0x0000FF00) >> 8 );
        ptr += snprintf(result + ptr, size - ptr, (flag == 0)?TO_HEX_FMT_U:TO_HEX_FMT_L, (abcd[i] & 0x00FF0000) >> 16);
        ptr += snprintf(result + ptr, size - ptr, (flag == 0)?TO_HEX_FMT_U:TO_HEX_FMT_L, (abcd[i] & 0xFF000000) >> 24);
    }
}


/**
 * @input: result -- store the calculation result
 *         size   -- size of result. Make sure it's at least 33 
 *                   since the result is a 32-byte hexdecimal string.
 *         message-- string to be encrypted
 *         flag   -- 0 means upper case output, 1 means lower case output
 * @return: 0 -- success
 *          1 -- result size less than 33
 *          2 -- calloc failed
 */
int32_t cal_md5(char *result, size_t size, const char *message, uint32_t flag){
    if (result == NULL || size < 33)
    {
        return 1;
    }
    
    uint32_t *w = (uint32_t *)calloc(16, sizeof(uint32_t));
    if(w == NULL)
    {
        return 2;
    }

    uint32_t i; // used in for loop

    uint32_t mes_len = strlen(message);
    uint32_t looptimes = (mes_len + 8) / 64 + 1;
    uint32_t abcd[] = {0x67452301, 0xEFCDAB89, 0x98BADCFE, 0x10325476};

    const uint32_t k[]={
        0xd76aa478,0xe8c7b756,0x242070db,0xc1bdceee,
        0xf57c0faf,0x4787c62a,0xa8304613,0xfd469501,0x698098d8,
        0x8b44f7af,0xffff5bb1,0x895cd7be,0x6b901122,0xfd987193,
        0xa679438e,0x49b40821,0xf61e2562,0xc040b340,0x265e5a51,
        0xe9b6c7aa,0xd62f105d,0x02441453,0xd8a1e681,0xe7d3fbc8,
        0x21e1cde6,0xc33707d6,0xf4d50d87,0x455a14ed,0xa9e3e905,
        0xfcefa3f8,0x676f02d9,0x8d2a4c8a,0xfffa3942,0x8771f681,
        0x6d9d6122,0xfde5380c,0xa4beea44,0x4bdecfa9,0xf6bb4b60,
        0xbebfbc70,0x289b7ec6,0xeaa127fa,0xd4ef3085,0x04881d05,
        0xd9d4d039,0xe6db99e5,0x1fa27cf8,0xc4ac5665,0xf4292244,
        0x432aff97,0xab9423a7,0xfc93a039,0x655b59c3,0x8f0ccc92,
        0xffeff47d,0x85845dd1,0x6fa87e4f,0xfe2ce6e0,0xa3014314,
        0x4e0811a1,0xf7537e82,0xbd3af235,0x2ad7d2bb,0xeb86d391
    };

    const uint32_t s[]={
        7,12,17,22,7,12,17,22,7,12,17,22,7,
        12,17,22,5,9,14,20,5,9,14,20,5,9,14,20,5,9,14,20,
        4,11,16,23,4,11,16,23,4,11,16,23,4,11,16,23,6,10,
        15,21,6,10,15,21,6,10,15,21,6,10,15,21
    };

    uint32_t pos = 0; // position pointer for message string
    uint32_t bkp_len = 64 * looptimes - mes_len;
    unsigned char *bkp_mes = (unsigned char *)calloc(1, bkp_len);
    if(bkp_mes == NULL)
    {
        free(w);
        return 2;
    }

    bkp_mes[0] = (unsigned char)(0x80);
    uint64_t mes_bit_len = ((uint64_t)mes_len) * 8;
    for(i = 0; i < 8; i++)
    {
        bkp_mes[bkp_len-i-1] = (unsigned char)((mes_bit_len & (0x00000000000000FF << (8 * (7 - i)))) >> (8 * (7 - i)));
    }
    
    for(i = 0; i < looptimes; i++)
    {
        memset(w, 0, 16 * sizeof(uint32_t));
        
        md5_process_part1(w, message, &pos, mes_len, bkp_mes); // compute w
        
        md5_process_part2(abcd, w, k, s); // calculate md5 and store the result in abcd
    }
    
    free(w);
    free(bkp_mes);

    format_output(result, size, abcd, flag);

    return 0;
}

#ifdef __cplusplus
}
#endif

2

/**
 * @author Horst Xu
 * @date 2015-07-10
 * @contact 271021733@qq.com
 */
#ifndef __MD5_H__
#define __MD5_H__

#include <stdint.h>
#include <stddef.h>

#ifdef __cplusplus
extern "C" {
#endif

/**
 * @input: result -- store the calculation result
 *         size   -- size of result. Make sure it's at least 33 
 *                   since the result is a 32-byte hexdecimal string.
 *         message-- string to be encrypted
 *         flag   -- 0 means upper case output, 1 means lower case output
 * @return: 0 -- success
 *          1 -- result size less than 33
 *          2 -- calloc failed
 */
int32_t cal_md5(char *result, size_t size, const char *message, uint32_t flag);

#ifdef __cplusplus
}
#endif

#endif //__MD5_H__

3

#include <stdio.h>
#include <stdint.h>
#include <string.h>

#include "md5.h"

int32_t main(void)
{
    char result[41];
    int32_t ret = -1;

    //test 1
    ret = cal_md5(result, sizeof(result), "abcdegfhijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz123", 1);
    if(ret == 0 && 0 == strncmp(result, "dd2fc541b65e2202d55beae0ecaf6528", strlen(result)))
    {
        printf("test 1 successful!
");
    }else
    {
        printf("test 1 failed!
");
    }

    //test 2
    ret = cal_md5(result, sizeof(result), "abcdegfhijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz1234", 0);
    if(ret == 0 && 0 == strncmp(result, "27FF2E8344E7E3F36F9C7E18D0EC82DF", strlen(result)))
    {
        printf("test 2 successful!
");
    }else
    {
        printf("test 2 failed!
");
    }

    //test 3
    ret = cal_md5(result, sizeof(result), "abcdegfhijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz12345", 0);
    if(ret == 0 && 0 == strncmp(result, "7A7B1279343946E3A5949BEA1B3BF8AF", strlen(result)))
    {
        printf("test 3 successful!
");
    }else
    {
        printf("test 3 failed!
");
    }

    //test 4
    ret = cal_md5(result, sizeof(result), "", 1);
    if(ret == 0 && 0 == strncmp(result, "d41d8cd98f00b204e9800998ecf8427e", strlen(result)))
    {
        printf("test 4 successful!
");
    }else
    {
        printf("test 4 failed!
");
    }

    return 0;
}