C实现md5功能

 md5在线验证：

在线MD5计算_ip33.com

代码如下：

#include "md5.h"
#include <string.h>
#include "stdio.h"/** 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 md5_starts(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(md5_context* ctx, const 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 Fctx->state[0] += A;ctx->state[1] += B;ctx->state[2] += C;ctx->state[3] += D;
}/** MD5 process buffer*/
void md5_update(md5_context* ctx, const 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),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),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*/
void md5_finish(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);md5_update(ctx, md5_padding, padn);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 md5(unsigned char* input, int ilen, unsigned char output[16])
{md5_context ctx;memset(&ctx, 0, sizeof(md5_context));md5_starts(&ctx);md5_update(&ctx, input, ilen);md5_finish(&ctx, output);
}

#ifndef __MD5_H__
#define __MD5_H__/*** \brief          MD5 context structure*/
typedef struct
{unsigned long total[2];     /*!< number of bytes processed  */unsigned long state[4];     /*!< intermediate digest state  */unsigned char buffer[64];   /*!< data block being processed */
}
md5_context;/*** \brief          MD5 context setup** \param ctx      context to be initialized*/void md5_starts(md5_context* ctx);/*** \brief          MD5 process buffer** \param ctx      MD5 context* \param input    buffer holding the  data* \param ilen     length of the input data*/void md5_update(md5_context* ctx, const unsigned char* input, int ilen);/*** \brief          MD5 final digest** \param ctx      MD5 context* \param output   MD5 checksum result*/void md5_finish(md5_context* ctx, unsigned char output[16]);/*** \brief          Output = MD5( input buffer )** \param input    buffer holding the  data* \param ilen     length of the input data* \param output   MD5 checksum result*/void md5(unsigned char* input, int ilen, unsigned char output[16]);
#endif