C++下写的MD5类，简单易用

//---------------------------------------------------------------------------
/////cpp文件

#pragma hdrstop

#include "MD5.h"

//---------------------------------------------------------------------------

#pragma package(smart_init)

/* Constants for MD5Transform routine. */
#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], UCHAR[64]));
static void Encode PROTO_LIST ((PUCHAR, UINT4*, UINT4));
static void Decode PROTO_LIST ((UINT4 *, PUCHAR, UINT4));
static void MD5_memcpy PROTO_LIST ((PUCHAR, PUCHAR, UINT4));
static void MD5_memset PROTO_LIST ((PUCHAR, int, UINT4));

static UCHAR 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
};

/* F, G, H and I are basic MD5 functions. */
#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)))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/*
  FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
  Rotation is separate from addition to prevent recomputation.
*/

#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);   }

/* MD5 initialization. Begins an MD5 operation, writing a new context. */
void MD5Init(MD5_CTX *context)
{
  context->count[0] = context->count[1] = 0;
  /* Load magic initialization constants.*/
  context->state[0] = 0x67452301;
  context->state[1] = 0xefcdab89;
  context->state[2] = 0x98badcfe;
  context->state[3] = 0x10325476;
}
/* MD5 block update operation. Continues an MD5 message-digest
  operation, processing another message block, and updating the
  context.*/
void MD5Update(MD5_CTX *context, PUCHAR input,UINT4 inputLen)
{
  UINT4 i, index, partLen;
  /* Compute number of bytes mod 64 */
  index = (UINT4)((context->count[0] >> 3) & 0x3F);
  /* Update number of bits */
  if ((context->count[0] += ((UINT4)inputLen << 3)) < ((UINT4)inputLen << 3))
    context->count[1]++;
  context->count[1] += ((UINT4)inputLen >> 29);

  partLen = 64 - index;

  /* Transform as many times as possible.*/
  if (inputLen >= partLen)
  {
    MD5_memcpy((PUCHAR)&context->buffer[index], (PUCHAR)input, partLen);
    MD5Transform (context->state, context->buffer);

    for (i = partLen; i + 63 < inputLen; i += 64)
      MD5Transform (context->state, &input[i]);

    index = 0;
  }
  else
   i = 0;
  /* Buffer remaining input */
  MD5_memcpy((PUCHAR)&context->buffer[index], (PUCHAR)&input[i],inputLen-i);
}
/* MD5 finalization. Ends an MD5 message-digest operation, writing the the message digest and zeroizing the context.*/
void MD5Final(UCHAR digest[],MD5_CTX * context)
{
  UCHAR bits[8];
  UINT4 index, padLen;
  /* Save number of bits */
  Encode (bits, context->count, 8);
  /* Pad out to 56 mod 64.*/
  index = (UINT4)((context->count[0] >> 3) & 0x3f);
  padLen = (index < 56) ? (56 - index) : (120 - index);
  MD5Update (context, PADDING, padLen);
  /* Append length (before padding) */
  MD5Update (context, bits, 8);
  /* Store state in digest */
  Encode (digest, context->state, 16);
  /* Zeroize sensitive information.*/
  MD5_memset ((PUCHAR)context, 0, sizeof (*context));
}

/* MD5 basic transformation. Transforms state based on block. */
static void MD5Transform (UINT4 state[], UCHAR block[])
{
  UINT4 a = state[0], b = state[1], c = state[2], d = state[3];
  UINT4 x[16];
  Decode (x, block, 64);
  /* Round 1 */
  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;
  /* Zeroize sensitive information.*/
  MD5_memset ((PUCHAR)x, (int)0, (UINT4)(sizeof(x)));
}
/*Encodes input (UINT4) into output (unsigned char). Assumes len is a multiple of 4.*/
static void Encode (PUCHAR output, UINT4 *input,UINT4 len)
{
  UINT4 i, j;
  for (i = 0, j = 0; j < len; i++, j += 4)
  {
    output[j]   = (UCHAR)(input[i] & 0xff);
    output[j+1] = (UCHAR)((input[i] >> 8) & 0xff);
    output[j+2] = (UCHAR)((input[i] >> 16) & 0xff);
    output[j+3] = (UCHAR)((input[i] >> 24) & 0xff);
  }
}
/* Decodes input (unsigned char) into output (UINT4). Assumes len is a multiple of 4.*/
static void Decode (UINT4 *output, PUCHAR input, UINT4 len)
{
  UINT4 i, j;
  for (i = 0, j = 0; j < len; i++, j += 4)
   output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) | (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}
/* Note: Replace "for loop" with standard memcpy if possible. */
static void MD5_memcpy (PUCHAR output,PUCHAR input, UINT4 len)
{
  UINT4 i;
  for (i = 0; i < len; i++)
   output[i] = input[i];
}
/* Note: Replace "for loop" with standard memset if possible. */
static void MD5_memset (PUCHAR output,int value,UINT4 len)
{
  UINT4 i;
  for (i = 0; i < len; i++)
   ((char *)output)[i] = (char)value;
}

AnsiString __fastcall MD5_CodeString(AnsiString Input)
{
  char Result[33]={0};
  int Len=Input.Length();
  unsigned char dst[16];
  char tmp[3];

  MD5_CTX  mc;
  MD5Init(&mc);
  MD5Update(&mc,Input.c_str(),Len);
  MD5Final(dst,&mc);

  for(int i=0;i<16;i++)
  {
    sprintf(tmp,"%02x",dst[i]);
    tmp[2]=0;
    strncat(Result,tmp,2);
  }
  Result[32]=0;
  return AnsiString(Result);
//  return AnsiString(UpperCase(Result));
}
//---------------------------------------------------------------------------
AnsiString __fastcall MD5_CodeFile(AnsiString FileName)
{
  if(!FileExists(FileName)) return AnsiString("");
  int Len=0;
  unsigned char dst[16];
  char res[33]={0};
  char tmp[3];
  MD5_CTX  mc;
  TMemoryStream *ms=new TMemoryStream();
  try
  {
    try
    {
      ms->LoadFromFile(FileName);
      Len=ms->Size;
      MD5Init(&mc);
      MD5Update(&mc,(unsigned char*)(ms->Memory),Len);
      MD5Final(dst,&mc);
      for(int i=0;i<16;i++)
      {
        sprintf(tmp,"%02x",dst[i]);
        tmp[2]=0;
        strncat(res,tmp,2);
      }
      res[32]=0;
    }
    catch(...)
    {
      res[0]=0;
    }
  }
  __finally
  {
    delete ms;  ms=NULL;
  }
  return AnsiString(res);

}

#ifndef _MD5_H_066A0C4C-8D5C-4698-8AF8-421A1CA8442C
#define _MD5_H_066A0C4C-8D5C-4698-8AF8-421A1CA8442C

#define MD5 5

#ifndef MD
  #define MD MD5
#endif

#ifndef PROTOTYPES
  #define PROTOTYPES 1
#endif

typedef unsigned char*          PUCHAR;
typedef unsigned short int      UINT2;
typedef unsigned int            UINT4;
typedef unsigned char           UCHAR;

#if PROTOTYPES
  #define PROTO_LIST(list) list
#else
  #define PROTO_LIST(list) ()
#endif

typedef struct
{
  UINT4 state[4];
  UINT4 count[2];
  UCHAR buffer[64];
} MD5_CTX;

void MD5Init PROTO_LIST ((MD5_CTX* Md5_ctx));
void MD5Update PROTO_LIST ((MD5_CTX* Md5_ctx, PUCHAR Input, UINT4 Legth));
void MD5Final PROTO_LIST ((UCHAR Digest[16], MD5_CTX* Md5_ctx));

//#ifdef MD5_BCB5
#include <vcl.h>
#include <stdio.h>
extern AnsiString __fastcall MD5_CodeString(AnsiString Input);
extern AnsiString __fastcall MD5_CodeFile(AnsiString FileName);
//#endif

#endif

以上就是C++MD5类了，采用BCB6.0编译的，其他编译器稍微修改下变量类型就好了。

调用方法如下：

String s = "admin";

s = MD5_CodeString(s);//其实只需要用到这个函数即可，其他的，在MD5类里面都已经全部搞定了，可以直接拿来用。

我们会发现，此时s = “21232f297a57a5a743894a0e4a801fc3”；