public PubKey Derivate(byte[] cc, uint nChild, out byte[] ccChild)
{
if (!IsCompressed)
{
throw new InvalidOperationException("The pubkey must be compressed");
}
if ((nChild >> 31) != 0)
{
throw new InvalidOperationException("A public key can't derivate an hardened child");
}
#if HAS_SPAN
Span <byte> vout = stackalloc byte[64];
vout.Clear();
Span <byte> pubkey = stackalloc byte[33];
this.ToBytes(pubkey, out _);
Hashes.BIP32Hash(cc, nChild, pubkey[0], pubkey.Slice(1), vout);
ccChild = new byte[32];;
vout.Slice(32, 32).CopyTo(ccChild);
return(new PubKey(this.ECKey.AddTweak(vout.Slice(0, 32)), true));
#else
byte[] lr = null;
byte[] l = new byte[32];
byte[] r = new byte[32];
var pubKey = ToBytes();
lr = Hashes.BIP32Hash(cc, nChild, pubKey[0], pubKey.Skip(1).ToArray());
Array.Copy(lr, l, 32);
Array.Copy(lr, 32, r, 0, 32);
ccChild = r;
BigInteger N = ECKey.CURVE.N;
BigInteger parse256LL = new BigInteger(1, l);
if (parse256LL.CompareTo(N) >= 0)
{
throw new InvalidOperationException("You won a prize ! this should happen very rarely. Take a screenshot, and roll the dice again.");
}
var q = ECKey.CURVE.G.Multiply(parse256LL).Add(ECKey.GetPublicKeyParameters().Q);
if (q.IsInfinity)
{
throw new InvalidOperationException("You won the big prize ! this would happen only 1 in 2^127. Take a screenshot, and roll the dice again.");
}
q = q.Normalize();
var p = new NBitcoin.BouncyCastle.Math.EC.FpPoint(ECKey.CURVE.Curve, q.XCoord, q.YCoord, true);
return(new PubKey(p.GetEncoded()));
#endif
}
public PubKey Derivate(byte[] cc, uint nChild, out byte[] ccChild)
{
byte[] lr = null;
var l = new byte[32];
var r = new byte[32];
if ((nChild >> 31) == 0)
{
byte[] pubKey = ToBytes();
lr = Hashes.BIP32Hash(cc, nChild, pubKey[0], pubKey.Skip(1).ToArray());
}
else
{
throw new InvalidOperationException("A public key can't derivate an hardened child");
}
Array.Copy(lr, l, 32);
Array.Copy(lr, 32, r, 0, 32);
ccChild = r;
BigInteger N = ECKey.CURVE.N;
var parse256LL = new BigInteger(1, l);
if (parse256LL.CompareTo(N) >= 0)
{
throw new InvalidOperationException("You won a prize ! this should happen very rarely. Take a screenshot, and roll the dice again.");
}
ECPoint q = ECKey.CURVE.G.Multiply(parse256LL).Add(ECKey.GetPublicKeyParameters().Q);
if (q.IsInfinity)
{
throw new InvalidOperationException("You won the big prize ! this would happen only 1 in 2^127. Take a screenshot, and roll the dice again.");
}
q = q.Normalize();
var p = new NBitcoin.BouncyCastle.Math.EC.FpPoint(ECKey.CURVE.Curve, q.XCoord, q.YCoord, true);
return(new PubKey(p.GetEncoded()));
}
