Creating a Hash with CNG

HashData.c

// Client should release HashData with HeapFree()
// e.g. HeapFree(GetProcessHeap(), 0, HashData);
// Ref. https://learn.microsoft.com/en-us/windows/win32/seccng/creating-a-hash-with-cng
NTSTATUS HashCreate (
	LPCWSTR		HashAlg,
	PBYTE		RawData,
	DWORD		RawDataSize,
	PBYTE		*HashData,
	DWORD		*HashDataSize
)
{
	BCRYPT_ALG_HANDLE	hAlg = NULL;
	BCRYPT_HASH_HANDLE	hHash = NULL;

	DWORD		cbData = 0, cbHash = 0, cbHashObject = 0;
	PBYTE		pbHashObject = NULL, pbHash = NULL;
	NTSTATUS	status = STATUS_UNSUCCESSFUL;

	if (!HashData || !HashDataSize) return status;

	// open an algorithm handle
	status = BCryptOpenAlgorithmProvider(
				&hAlg,
				HashAlg,
				NULL,
				0);
	if (!NT_SUCCESS(status)) goto error;

	// calculate the size of the buffer to hold the hash object
	status = BCryptGetProperty(
				hAlg,
				BCRYPT_OBJECT_LENGTH,
				(PBYTE)&cbHashObject,
				sizeof(DWORD),
				&cbData,
				0);
	if (!NT_SUCCESS(status)) goto error;

	// allocate the hash object on the heap
	pbHashObject = (PBYTE)HeapAlloc(GetProcessHeap(), 0, cbHashObject);
	if (NULL == pbHashObject) goto error;

	// calculate the length of the hash
	status = BCryptGetProperty(
				hAlg,
				BCRYPT_HASH_LENGTH,
				(PBYTE)&cbHash,
				sizeof(DWORD),
				&cbData,
				0);
	if (!NT_SUCCESS(status)) goto error;

	// allocate the hash buffer on the heap
	pbHash = (PBYTE)HeapAlloc(GetProcessHeap(), 0, cbHash);
	if (NULL == pbHash) goto error;

	// create hash
	status = BCryptCreateHash(
				hAlg,
				&hHash,
				pbHashObject,
				cbHashObject,
				NULL,
				0,
				0);
	if (!NT_SUCCESS(status)) goto error;

	// hash some data
	status = BCryptHashData(
				hHash,
				RawData,
				RawDataSize,
				0);
	if (!NT_SUCCESS(status)) goto error;

	// close the hash
	status = BCryptFinishHash(
				hHash,
				pbHash,
				cbHash,
				0);
	if (NT_SUCCESS(status)) {
		*HashData = pbHash;
		*HashDataSize = cbHash;
	}

error:
	if (hAlg) BCryptCloseAlgorithmProvider(hAlg, 0);
	if (hHash) BCryptDestroyHash(hHash);
	if (pbHashObject) HeapFree(GetProcessHeap(), 0, pbHashObject);
	return status;
}

int main(int argc, char *argv[])
{
	PBYTE buffer, hashVal;
	DWORD bufferSize, hashValSize;

	if (argc < 2) return 1;

	FileRead(argv[1], &buffer, &bufferSize);

	printf("SHA256 :\n    ");
	if (NT_SUCCESS(HashCreate(
					BCRYPT_SHA256_ALGORITHM,
					buffer,
					bufferSize,
					&hashVal,
					&hashValSize)))
	{
		for (int index = 0; index < hashValSize; index++) {
			printf("%02X", hashVal[index]);
			printf("%s", (index + 1) % 16 ? " " : "\n    ");
		}
		HeapFree(GetProcessHeap(), 0, hashVal);
	}
	HeapFree(GetProcessHeap(), 0, buffer);

	return 0;
}