说明：提供MD5算法代码和测试示例代码
简介：MD5（Message Digest Algorithm 5）是一种常用的加密算法，它将任意长度的“字节串”映射为一个128位的大数，并且设计者寄希望于它无法逆向生成或逆向碰撞。
MD5算法具有以下特性：
确定性：对于相同的输入，MD5算法总是产生相同的结果。
非逆向性：已知一个MD5散列，要找到原始输入是非常困难的。即使输入只有微小的变化，MD5的结果也会有巨大的差异。
雪崩效应：当输入数据发生变化时，MD5的结果会产生极大的差异，这使得它适合用于检测数据的完整性。
然而，随着计算机科学的发展，MD5已经被证明存在一些弱点，特别是关于碰撞的问题。因此，它现在主要用于检测数据的完整性，而不是用于安全敏感的应用，如密码存储。
例如，你可以使用MD5来检查下载的文件是否被篡改，或者在数据库中存储密码时确保密码的正确性。但请注意，不应该用MD5来存储密码或执行敏感的身份验证。在这种情况下，应该使用更安全的哈希函数，如bcrypt或Argon2。
#include <stdio.h>
#include <stdint.h>
#include <string.h>
/* md5 ------------------------------------------------------------------------------------------------------------- */
#if 1
typedef struct {
unsigned long total[2]; /*!< number of bytes processed 处理的字节数*/
unsigned long state[4]; /*!< intermediate digest state 摘要状态*/
unsigned char buffer[64]; /*!< data block being processed 正在处理的数据块*/
unsigned char ipad[64]; /*!< HMAC: inner padding HMAC：内部填充 */
unsigned char opad[64]; /*!< HMAC: outer padding HMAC：外部填充 */
} tiny_md5_context;
#endif
#define TINY_CRYPT_MD5
#if defined(TINY_CRYPT_MD5)
/*
* 32-bit integer manipulation macros (little endian)
*/
#ifndef GET_ULONG_LE
#define GET_ULONG_LE(n,b,i)
{
(n) = ( (unsigned long) (b)[(i) ] )
| ( (unsigned long) (b)[(i) + 1] << 8 )
| ( (unsigned long) (b)[(i) + 2] << 16 )
| ( (unsigned long) (b)[(i) + 3] << 24 );
}
#endif
#ifndef PUT_ULONG_LE
#define PUT_ULONG_LE(n,b,i)
{
(b)[(i) ] = (unsigned char) ( (n) );
(b)[(i) + 1] = (unsigned char) ( (n) >> 8 );
(b)[(i) + 2] = (unsigned char) ( (n) >> 16 );
(b)[(i) + 3] = (unsigned char) ( (n) >> 24 );
}
#endif
/*
* MD5 context setup
*/
void tiny_md5_starts(tiny_md5_context * ctx)
{
ctx->total[0] = 0;
ctx->total[1] = 0;
ctx->state[0] = 0x67452301;
ctx->state[1] = 0xEFCDAB89;
ctx->state[2] = 0x98BADCFE;
ctx->state[3] = 0x10325476;
}
static void md5_process(tiny_md5_context * ctx, unsigned char data[64])
{
unsigned long X[16], A, B, C, D;
GET_ULONG_LE(X[0], data, 0);
GET_ULONG_LE(X[1], data, 4);
GET_ULONG_LE(X[2], data, 8);
GET_ULONG_LE(X[3], data, 12);
GET_ULONG_LE(X[4], data, 16);
GET_ULONG_LE(X[5], data, 20);
GET_ULONG_LE(X[6], data, 24);
GET_ULONG_LE(X[7], data, 28);
GET_ULONG_LE(X[8], data, 32);
GET_ULONG_LE(X[9], data, 36);
GET_ULONG_LE(X[10], data, 40);
GET_ULONG_LE(X[11], data, 44);
GET_ULONG_LE(X[12], data, 48);
GET_ULONG_LE(X[13], data, 52);
GET_ULONG_LE(X[14], data, 56);
GET_ULONG_LE(X[15], data, 60);
#define S(x,n) ((x << n) | ((x & 0xFFFFFFFF) >> (32 - n)))
#define P(a,b,c,d,k,s,t)
{
a += F(b,c,d) + X[k] + t; a = S(a,s) + b;
}
A = ctx->state[0];
B = ctx->state[1];
C = ctx->state[2];
D = ctx->state[3];
#define F(x,y,z) (z ^ (x & (y ^ z)))
P(A, B, C, D, 0, 7, 0xD76AA478);
P(D, A, B, C, 1, 12, 0xE8C7B756);
P(C, D, A, B, 2, 17, 0x242070DB);
P(B, C, D, A, 3, 22, 0xC1BDCEEE);
P(A, B, C, D, 4, 7, 0xF57C0FAF);
P(D, A, B, C, 5, 12, 0x4787C62A);
P(C, D, A, B, 6, 17, 0xA8304613);
P(B, C, D, A, 7, 22, 0xFD469501);
P(A, B, C, D, 8, 7, 0x698098D8);
P(D, A, B, C, 9, 12, 0x8B44F7AF);
P(C, D, A, B, 10, 17, 0xFFFF5BB1);
P(B, C, D, A, 11, 22, 0x895CD7BE);
P(A, B, C, D, 12, 7, 0x6B901122);
P(D, A, B, C, 13, 12, 0xFD987193);
P(C, D, A, B, 14, 17, 0xA679438E);
P(B, C, D, A, 15, 22, 0x49B40821);
#undef F
#define F(x,y,z) (y ^ (z & (x ^ y)))
P(A, B, C, D, 1, 5, 0xF61E2562);
P(D, A, B, C, 6, 9, 0xC040B340);
P(C, D, A, B, 11, 14, 0x265E5A51);
P(B, C, D, A, 0, 20, 0xE9B6C7AA);
P(A, B, C, D, 5, 5, 0xD62F105D);
P(D, A, B, C, 10, 9, 0x02441453);
P(C, D, A, B, 15, 14, 0xD8A1E681);
P(B, C, D, A, 4, 20, 0xE7D3FBC8);
P(A, B, C, D, 9, 5, 0x21E1CDE6);
P(D, A, B, C, 14, 9, 0xC33707D6);
P(C, D, A, B, 3, 14, 0xF4D50D87);
P(B, C, D, A, 8, 20, 0x455A14ED);
P(A, B, C, D, 13, 5, 0xA9E3E905);
P(D, A, B, C, 2, 9, 0xFCEFA3F8);
P(C, D, A, B, 7, 14, 0x676F02D9);
P(B, C, D, A, 12, 20, 0x8D2A4C8A);
#undef F
#define F(x,y,z) (x ^ y ^ z)
P(A, B, C, D, 5, 4, 0xFFFA3942);
P(D, A, B, C, 8, 11, 0x8771F681);
P(C, D, A, B, 11, 16, 0x6D9D6122);
P(B, C, D, A, 14, 23, 0xFDE5380C);
P(A, B, C, D, 1, 4, 0xA4BEEA44);
P(D, A, B, C, 4, 11, 0x4BDECFA9);
P(C, D, A, B, 7, 16, 0xF6BB4B60);
P(B, C, D, A, 10, 23, 0xBEBFBC70);
P(A, B, C, D, 13, 4, 0x289B7EC6);
P(D, A, B, C, 0, 11, 0xEAA127FA);
P(C, D, A, B, 3, 16, 0xD4EF3085);
P(B, C, D, A, 6, 23, 0x04881D05);
P(A, B, C, D, 9, 4, 0xD9D4D039);
P(D, A, B, C, 12, 11, 0xE6DB99E5);
P(C, D, A, B, 15, 16, 0x1FA27CF8);
P(B, C, D, A, 2, 23, 0xC4AC5665);
#undef F
#define F(x,y,z) (y ^ (x | ~z))
P(A, B, C, D, 0, 6, 0xF4292244);
P(D, A, B, C, 7, 10, 0x432AFF97);
P(C, D, A, B, 14, 15, 0xAB9423A7);
P(B, C, D, A, 5, 21, 0xFC93A039);
P(A, B, C, D, 12, 6, 0x655B59C3);
P(D, A, B, C, 3, 10, 0x8F0CCC92);
P(C, D, A, B, 10, 15, 0xFFEFF47D);
P(B, C, D, A, 1, 21, 0x85845DD1);
P(A, B, C, D, 8, 6, 0x6FA87E4F);
P(D, A, B, C, 15, 10, 0xFE2CE6E0);
P(C, D, A, B, 6, 15, 0xA3014314);
P(B, C, D, A, 13, 21, 0x4E0811A1);
P(A, B, C, D, 4, 6, 0xF7537E82);
P(D, A, B, C, 11, 10, 0xBD3AF235);
P(C, D, A, B, 2, 15, 0x2AD7D2BB);
P(B, C, D, A, 9, 21, 0xEB86D391);
#undef F
ctx->state[0] += A;
ctx->state[1] += B;
ctx->state[2] += C;
ctx->state[3] += D;
}
/*
* MD5 process buffer
*/
void tiny_md5_update(tiny_md5_context * ctx, unsigned char *input, int ilen)
{
int fill;
unsigned long left;
if (ilen <= 0)
return;
left = ctx->total[0] & 0x3F;
fill = 64 - left;
ctx->total[0] += ilen;
ctx->total[0] &= 0xFFFFFFFF;
if (ctx->total[0] < (unsigned long)ilen)
ctx->total[1]++;
if (left && ilen >= fill) {
memcpy((void *)(ctx->buffer + left), (void *)input, fill);
md5_process(ctx, ctx->buffer);
input += fill;
ilen -= fill;
left = 0;
}
while (ilen >= 64) {
md5_process(ctx, input);
input += 64;
ilen -= 64;
}
if (ilen > 0) {
memcpy((void *)(ctx->buffer + left), (void *)input, ilen);
}
}
static const unsigned char md5_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
};
/*
* MD5 final digest MD5最终摘要
*/
void tiny_md5_finish(tiny_md5_context * ctx, unsigned char output[16])
{
unsigned long last, padn;
unsigned long high, low;
unsigned char msglen[8];
high = (ctx->total[0] >> 29)
| (ctx->total[1] << 3);
low = (ctx->total[0] << 3);
PUT_ULONG_LE(low, msglen, 0);
PUT_ULONG_LE(high, msglen, 4);
last = ctx->total[0] & 0x3F;
padn = (last < 56) ? (56 - last) : (120 - last);
tiny_md5_update(ctx, (unsigned char *)md5_padding, padn);
tiny_md5_update(ctx, msglen, 8);
PUT_ULONG_LE(ctx->state[0], output, 0);
PUT_ULONG_LE(ctx->state[1], output, 4);
PUT_ULONG_LE(ctx->state[2], output, 8);
PUT_ULONG_LE(ctx->state[3], output, 12);
}
/*
* output = MD5( input buffer )
*/
void tiny_md5(unsigned char *input, int ilen, unsigned char output[16])
{
tiny_md5_context ctx;
tiny_md5_starts(&ctx);
tiny_md5_update(&ctx, input, ilen);
tiny_md5_finish(&ctx, output);
memset(&ctx, 0, sizeof(tiny_md5_context));
}
/*
* MD5 HMAC context setup MD5 HMAC上下文设置
*/
void tiny_md5_hmac_starts(tiny_md5_context * ctx, unsigned char *key, int keylen)
{
int i;
unsigned char sum[16];
if (keylen > 64) {
tiny_md5(key, keylen, sum);
keylen = 16;
key = sum;
}
memset(ctx->ipad, 0x36, 64);
memset(ctx->opad, 0x5C, 64);
for (i = 0; i < keylen; i++) {
ctx->ipad[i] = (unsigned char)(ctx->ipad[i] ^ key[i]);
ctx->opad[i] = (unsigned char)(ctx->opad[i] ^ key[i]);
}
tiny_md5_starts(ctx);
tiny_md5_update(ctx, ctx->ipad, 64);
memset(sum, 0, sizeof(sum));
}
/*
* MD5 HMAC process buffer MD5 HMAC进程缓冲区
*/
void tiny_md5_hmac_update(tiny_md5_context * ctx, unsigned char *input, int ilen)
{
tiny_md5_update(ctx, input, ilen);
}
/*
* MD5 HMAC final digest MD5 HMAC最终摘要
*/
void tiny_md5_hmac_finish(tiny_md5_context * ctx, unsigned char output[16])
{
unsigned char tmpbuf[16];
tiny_md5_finish(ctx, tmpbuf);
tiny_md5_starts(ctx);
tiny_md5_update(ctx, ctx->opad, 64);
tiny_md5_update(ctx, tmpbuf, 16);
tiny_md5_finish(ctx, output);
memset(tmpbuf, 0, sizeof(tmpbuf));
}
/*
* output = HMAC-MD5( hmac key, input buffer )
*/
void tiny_md5_hmac(unsigned char *key, int keylen, unsigned char *input, int ilen,unsigned char *od)
{
unsigned char output[16];
tiny_md5_context ctx;
tiny_md5_hmac_starts(&ctx, key, keylen);
tiny_md5_hmac_update(&ctx, input, ilen);
tiny_md5_hmac_finish(&ctx, output);
/*增加*/
for (uint8_t var = 0; var < 16; ++var)
{
*(od+var) = output[var];
}
/*增加*/
memset(&ctx, 0, sizeof(tiny_md5_context));
}
#endif
//测试
int main()
{
uint8_t data[] = {0x12, 0x34, 0x56, 0x78};
uint8_t output[16];
tiny_md5((unsigned char *)&data[0],4,(unsigned char *)&output[0]);
for (uint8_t var = 0; var < 16; ++var)
{
printf("%02X",output[var]);
}
printf("
");
return 0;
}
//计算结果
//891A26E0581A7F2C9A574CEFF1549EE1