ADVAPI32中的MD5算法

#include <windows.h>
/* Data structure for MD5 (Message-Digest) computation */
typedef struct {
ULONG i[2];                          /* number of _bits_ handled mod 2^64 */
ULONG buf[4];                                           /* scratch buffer */
unsigned char in[64];                                     /* input buffer */
unsigned char digest[16];            /* actual digest after MD5Final call */
} MD5_CTX;
#define MD5DIGESTLEN 16
#define PROTO_LIST(list)    list
/*
* MTS: Each of these assumes MD5_CTX is locked against simultaneous use.
*/
typedef void (WINAPI* PMD5Init) PROTO_LIST ((MD5_CTX *));
typedef void (WINAPI* PMD5Update) PROTO_LIST ((MD5_CTX *, const unsigned char *, unsigned int));
typedef void (WINAPI* PMD5Final )PROTO_LIST ((MD5_CTX *));
PMD5Init MD5Init = NULL;
PMD5Update MD5Update = NULL;
PMD5Final MD5Final = NULL;
const char *Hex2ASC(const BYTE *Hex, int Len)
{
static char  ASC[4096 * 2];
int    i;
for (i = 0; i < Len; i++)
{
 ASC[i * 2] = "0123456789ABCDEF"[Hex[i] >> 4];
 ASC[i * 2 + 1] = "0123456789ABCDEF"[Hex[i] & 0x0F];
}
ASC[i * 2] = ''''\0'''';
return ASC;
}
int main()
{
MD5_CTX ctx;
unsigned char buf[4] = "1233";
HINSTANCE hDLL;
if ( (hDLL = LoadLibrary("advapi32.dll")) > 0 )
{
 MD5Init = (PMD5Init)GetProcAddress(hDLL,"MD5Init");
 MD5Update = (PMD5Update)GetProcAddress(hDLL,"MD5Update");
 MD5Final = (PMD5Final)GetProcAddress(hDLL,"MD5Final");
 MD5Init(&ctx);
 MD5Update(&ctx,buf,4);
 MD5Final(&ctx);
 printf(Hex2ASC(ctx.digest,16));
}
return 0;
}