public Win7SP800_108_CTR_HMACSHA512Provider(byte* pbKdk, uint cbKdk)
 {
     _hashHandle = CachedAlgorithmHandles.HMAC_SHA512.CreateHmac(pbKdk, cbKdk);
 }
 // 'pbExpectedDigest' must point to a '_hmacAlgorithmDigestLengthInBytes'-length buffer
 private bool ValidateHash(BCryptHashHandle hashHandle, byte* pbInput, uint cbInput, byte* pbExpectedDigest)
 {
     byte* pbActualDigest = stackalloc byte[checked((int)_hmacAlgorithmDigestLengthInBytes)];
     hashHandle.HashData(pbInput, cbInput, pbActualDigest, _hmacAlgorithmDigestLengthInBytes);
     return CryptoUtil.TimeConstantBuffersAreEqual(pbExpectedDigest, pbActualDigest, _hmacAlgorithmDigestLengthInBytes);
 }