public static bool VerifySignature(
byte[] sig, int sigoffset,
byte[] m, int moffset, int mlen,
byte[] pk, int pkoffset)
{
byte[] h;
byte[] checkr = new byte[32];
GroupElementP3 A;
GroupElementP2 R;
if ((sig[sigoffset + 63] & 224) != 0)
{
return(false);
}
if (GroupOperations.ge_frombytes_negate_vartime(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);
h = hasher.Finish();
ScalarOperations.sc_reduce(h);
var sm32 = new byte[32];//todo: remove allocation
Array.Copy(sig, sigoffset + 32, sm32, 0, 32);
GroupOperations.ge_double_scalarmult_vartime(out R, h, ref A, sm32);
GroupOperations.ge_tobytes(checkr, 0, ref R);
var result = CryptoExtensions.ConstantTimeEquals(checkr, 0, sig, sigoffset, 32);
CryptoExtensions.Wipe(h);
CryptoExtensions.Wipe(checkr);
return(result);
}
