public static bool CryptoSignVerify(
byte[] sig, int sigoffset,
byte[] m, int moffset, int mlen,
byte[] pk, int pkoffset)
{
var checker = new byte[32];
GroupElementP3 A;
GroupElementP2 R;
if ((sig[sigoffset + 63] & 224) != 0)
{
return(false);
}
if (GroupOperations.FromBytes(out A, pk, pkoffset) != 0)
{
return(false);
}
var hasher = new Sha512();
hasher.Update(sig, sigoffset, 32);
hasher.Update(pk, pkoffset, 32);
hasher.Update(m, moffset, mlen);
var h = hasher.Finalize();
ScalarOperations.Reduce(h);
var sm32 = new byte[32];
Array.Copy(sig, sigoffset + 32, sm32, 0, 32);
GroupOperations.DoubleScalarMult(out R, h, ref A, sm32);
GroupOperations.ToBytes(checker, 0, ref R);
var result = CryptoBytes.ConstantTimeEquals(checker, 0, sig, sigoffset, 32);
CryptoBytes.Wipe(h);
CryptoBytes.Wipe(checker);
return(result);
}