String __fastcall Unit1::getFileMD5(char *filename) {

	HCRYPTHASH hHash;
	HCRYPTPROV hProv;
	BYTE md5hash[16];
	DWORD md5hash_size, dwSize;
	static char str_hash[33];
	int i;
	ZeroMemory(str_hash, sizeof(str_hash));
	ZeroMemory(md5hash, sizeof(md5hash));
	CryptAcquireContext(&hProv, NULL,
		NULL, PROV_RSA_FULL, 0);
	CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash);

	FILE *f = fopen(filename, "rb");

	fseek(f, 0, SEEK_END);
	int size = ftell(f);
	int size1 = size;
	int readed = 0;
	while (size1 > 0) {
		int len = 0;
		if (size1 - 50000000 >= 0) {
			len = 50000000;
		}
		else {
			len = size1;
		}
		fseek(f, readed, SEEK_SET);
		fread(buf, 1, len, f);
		size1 -= len;
		readed += len;
		CryptHashData(hHash, buf, len, 0);
	}
	fclose(f);

	dwSize = sizeof(md5hash_size);

	CryptGetHashParam(hHash, HP_HASHSIZE, (BYTE*) & md5hash_size, &dwSize, 0);

	CryptGetHashParam(hHash, HP_HASHVAL, md5hash, &md5hash_size, 0);

	CryptDestroyHash(hHash);

	CryptReleaseContext(hProv, 0);

	for (i = 0; i < md5hash_size; i++)
		sprintf(str_hash + 2 * i, "%2.2x", md5hash[i]);

	static char *md5str = str_hash;
	return md5str;
}