public static EcdhTuple EcdhDecode(this EcdhTuple mask, byte[] recieverSK)
{
EcdhTuple unmask = mask;
byte[] sharedSec1 = Cryptography.Crypto.Default.Hash256(ScalarFunctions.MulWithPoint(mask.senderPK, recieverSK));
byte[] sharedSec2 = Cryptography.Crypto.Default.Hash256(sharedSec1);
unmask.mask = ScalarFunctions.Sub(mask.mask, sharedSec1);
unmask.amount = ScalarFunctions.Sub(mask.amount, sharedSec2);
return(unmask);
}
public static EcdhTuple EcdhEncode(this EcdhTuple unmask, ECPoint receiverPk)
{
EcdhTuple ret = new EcdhTuple();
byte[] esk = SchnorrNonLinkable.GenerateRandomScalar();
ret.senderPK = ECCurve.Secp256r1.G * esk;
byte[] sharedSec1 = Cryptography.Crypto.Default.Hash256(ScalarFunctions.MulWithPoint(receiverPk, esk));
byte[] sharedSec2 = Cryptography.Crypto.Default.Hash256(sharedSec1);
ret.mask = ScalarFunctions.Add(unmask.mask, sharedSec1);
ret.amount = ScalarFunctions.Add(unmask.amount, sharedSec2);
return(ret);
}
public void ECDH_ENCODE_TEST()
{
byte[] RecieverSK = SchnorrNonLinkable.GenerateRandomScalar();
ECPoint RecieverPK = ECCurve.Secp256r1.G * RecieverSK;
byte[] u_mask = new byte[32];
byte[] u_amount = new byte[32];
ECPoint pt = new ECPoint();
EcdhTuple unmask = new EcdhTuple(u_mask, u_amount, pt);
EcdhTuple mask = unmask.EcdhEncode(RecieverPK);
EcdhTuple t_unmask = mask.EcdhDecode(RecieverSK);
unmask.amount.ToHexString().Should().Be(t_unmask.amount.ToHexString());
unmask.mask.ToHexString().Should().Be(t_unmask.mask.ToHexString());
}
