private bool ValidateClientHandshakeDigest(byte[] vec, int doffset)
{
var key = new byte[30];
Array.Copy(GenuineFPKey, key, 30);
var hash = ComputeHandshakeDigest1(vec, key, doffset);
return Enumerable.Range(doffset, 32).Select(i => vec[i]).SequenceEqual(hash);
}