[c++ snippet] MD5 of string using wincrpyt API

Hi,

I always thought calculating the MD5 digest of a string required adding external code, i was using this:

http://www.zedwood.com/article/121/cpp-md5-function

which works fine.

I was messing around with Windows crypt api, and noticed one can easily calculate the digest using WinCrypt APIs:

string MD5(string input)
{
	HCRYPTPROV CryptProv; 
	HCRYPTHASH CryptHash; 
	BYTE BytesHash[33];//!
	DWORD dwHashLen;
	string final;	if(CryptAcquireContext(&CryptProv, 
		NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_MACHINE_KEYSET)) 
	{
		if(CryptCreateHash(CryptProv, CALG_MD5, 0, 0, &CryptHash)) 
		{
			if(CryptHashData(CryptHash, (BYTE*)input.c_str(), input.length(), 0))
			{
				if(CryptGetHashParam(CryptHash, HP_HASHVAL, BytesHash, &dwHashLen, 0)) 
				{
					final.clear();
					string hexcharset = "0123456789ABCDEF";
					for(int j = 0; j < 16; j++)
					{
						final += hexcharset.substr(((BytesHash[j] >> 4) & 0xF),1);
						final += hexcharset.substr(((BytesHash[j]) & 0x0F),1);
					}
				}
			}
		}
	}	CryptDestroyHash(CryptHash); 
	CryptReleaseContext(CryptProv, 0); 
	return final; 
}

(dont forget #include <wincrypt.h>)

can be tweaked for other hashes, too. Just check the definitions in <wincrypt.h>.

nice weekend, everyone

dp0