public ExtKey GetParentExtKey(ExtPubKey parent)
{
if(parent == null)
throw new ArgumentNullException("parent");
if(Depth == 0)
throw new InvalidOperationException("This ExtKey is the root key of the HD tree");
if(IsHardened)
throw new InvalidOperationException("This private key is hardened, so you can't get its parent");
var expectedFingerPrint = parent.CalculateChildFingerprint();
if(parent.Depth != this.Depth - 1 || !expectedFingerPrint.SequenceEqual(vchFingerprint))
throw new ArgumentException("The parent ExtPubKey is not the immediate parent of this ExtKey", "parent");
byte[] l = null;
byte[] ll = new byte[32];
byte[] lr = new byte[32];
var pubKey = parent.PubKey.ToBytes();
l = Hashes.BIP32Hash(parent.vchChainCode, nChild, pubKey[0], pubKey.SafeSubarray(1));
Array.Copy(l, ll, 32);
Array.Copy(l, 32, lr, 0, 32);
var ccChild = lr;
BigInteger parse256LL = new BigInteger(1, ll);
BigInteger N = ECKey.CURVE.N;
if(!ccChild.SequenceEqual(vchChainCode))
throw new InvalidOperationException("The derived chain code of the parent is not equal to this child chain code");
var keyBytes = PrivateKey.ToBytes();
var key = new BigInteger(1, keyBytes);
BigInteger kPar = key.Add(parse256LL.Negate()).Mod(N);
var keyParentBytes = kPar.ToByteArrayUnsigned();
if(keyParentBytes.Length < 32)
keyParentBytes = new byte[32 - keyParentBytes.Length].Concat(keyParentBytes).ToArray();
var parentExtKey = new ExtKey
{
vchChainCode = parent.vchChainCode,
nDepth = parent.Depth,
vchFingerprint = parent.Fingerprint,
nChild = parent.nChild,
key = new Key(keyParentBytes)
};
return parentExtKey;
}
public BigInteger Subtract(
BigInteger n)
{
if (n.sign == 0)
return this;
if (this.sign == 0)
return n.Negate();
if (this.sign != n.sign)
return Add(n.Negate());
int compare = CompareNoLeadingZeroes(0, magnitude, 0, n.magnitude);
if (compare == 0)
return Zero;
BigInteger bigun, lilun;
if (compare < 0)
{
bigun = n;
lilun = this;
}
else
{
bigun = this;
lilun = n;
}
return new BigInteger(this.sign * compare, doSubBigLil(bigun.magnitude, lilun.magnitude), true);
}
public BigInteger Add(
BigInteger value)
{
if (this.sign == 0)
return value;
if (this.sign != value.sign)
{
if (value.sign == 0)
return this;
if (value.sign < 0)
return Subtract(value.Negate());
return value.Subtract(Negate());
}
return AddToMagnitude(value.magnitude);
}
public BigInteger ModPow(BigInteger e, BigInteger m)
{
if (m.sign < 1)
throw new ArithmeticException("Modulus must be positive");
if (m.Equals(One))
return Zero;
if (e.sign == 0)
return One;
if (sign == 0)
return Zero;
bool negExp = e.sign < 0;
if (negExp)
e = e.Negate();
BigInteger result = this.Mod(m);
if (!e.Equals(One))
{
if ((m.magnitude[m.magnitude.Length - 1] & 1) == 0)
{
result = ModPowBarrett(result, e, m);
}
else
{
result = ModPowMonty(result, e, m, true);
}
}
if (negExp)
result = result.ModInverse(m);
return result;
}
