/// <summary> Gets shared secret. </summary>
///
/// def get_shared_secret(priv, pub) :
/// pub_point = pub.point()
/// priv_point = int(repr(priv),16)
/// res = pub_point * priv_point
/// res_hex = '%032x' % res.x()
/// return res_hex
///
/// <remarks> Paul, 26/10/2015. </remarks>
///
/// <returns> The shared secret. </returns>
static public byte[] GetSharedSecret(KeyPair priv, PublicKey pub)
{
var ps = SecNamedCurves.GetByName("secp256k1");
BigInteger ipriv = new BigInteger(1, priv.PrivateKeyBytes);
ECPoint pubPoint = pub.GetECPoint();
ECPoint shared = pubPoint.Multiply(ipriv);
BigInteger s = shared.X.ToBigInteger();
byte[] data = s.ToByteArray();
int leadingZeros = -1;
while (data[++leadingZeros] == 0)
{
;
}
byte[] result = new byte[data.Length - leadingZeros];
Buffer.BlockCopy(data, leadingZeros, result, 0, result.Length);
return(result);
}
private void btnCombine_Click(object sender, EventArgs e)
{
// What is input #1?
string input1 = txtInput1.Text;
string input2 = txtInput2.Text;
PublicKey pub1 = null, pub2 = null;
KeyPair kp1 = null, kp2 = null;
if (KeyPair.IsValidPrivateKey(input1))
{
pub1 = kp1 = new KeyPair(input1);
}
else if (PublicKey.IsValidPublicKey(input1))
{
pub1 = new PublicKey(input1);
}
else
{
MessageBox.Show("Input key #1 is not a valid Public Key or Private Key Hex", "Can't combine", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
if (KeyPair.IsValidPrivateKey(input2))
{
pub2 = kp2 = new KeyPair(input2);
}
else if (PublicKey.IsValidPublicKey(input2))
{
pub2 = new PublicKey(input2);
}
else
{
MessageBox.Show("Input key #2 is not a valid Public Key or Private Key Hex", "Can't combine", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
if (kp1 == null && kp2 == null && rdoAdd.Checked == false)
{
MessageBox.Show("Can't multiply two public keys. At least one of the keys must be a private key.",
"Can't combine", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
if (pub1.IsCompressedPoint != pub2.IsCompressedPoint)
{
MessageBox.Show("Can't combine a compressed key with an uncompressed key.", "Can't combine", MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
if (pub1.AddressBase58 == pub2.AddressBase58)
{
if (MessageBox.Show("Both of the key inputs have the same public key hash. You can continue, but " +
"the results are probably going to be wrong. You might have provided the wrong " +
"information, such as two parts from the same side of the transaction, instead " +
"of one part from each side. Continue anyway?", "Duplicate Key Warning", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning) != DialogResult.OK)
{
return;
}
}
var ps = Org.BouncyCastle.Asn1.Sec.SecNamedCurves.GetByName("secp256k1");
// Combining two private keys?
if (kp1 != null && kp2 != null)
{
BigInteger e1 = new BigInteger(1, kp1.PrivateKeyBytes);
BigInteger e2 = new BigInteger(1, kp2.PrivateKeyBytes);
BigInteger ecombined = (rdoAdd.Checked ? e1.Add(e2) : e1.Multiply(e2)).Mod(ps.N);
System.Diagnostics.Debug.WriteLine(kp1.PublicKeyHex);
System.Diagnostics.Debug.WriteLine(kp2.PublicKeyHex);
KeyPair kpcombined = new KeyPair(Util.Force32Bytes(ecombined.ToByteArrayUnsigned()), compressed: kp1.IsCompressedPoint);
txtOutputAddress.Text = kpcombined.AddressBase58;
txtOutputPubkey.Text = kpcombined.PublicKeyHex.Replace(" ", "");
txtOutputPriv.Text = kpcombined.PrivateKeyBase58;
}
else if (kp1 != null || kp2 != null)
{
// Combining one public and one private
KeyPair priv = (kp1 == null) ? kp2 : kp1;
PublicKey pub = (kp1 == null) ? pub1 : pub2;
ECPoint point = pub.GetECPoint();
ECPoint combined = rdoAdd.Checked ? point.Add(priv.GetECPoint()) : point.Multiply(new BigInteger(1, priv.PrivateKeyBytes));
ECPoint combinedc = ps.Curve.CreatePoint(combined.X.ToBigInteger(), combined.Y.ToBigInteger(), priv.IsCompressedPoint);
PublicKey pkcombined = new PublicKey(combinedc.GetEncoded());
txtOutputAddress.Text = pkcombined.AddressBase58;
txtOutputPubkey.Text = pkcombined.PublicKeyHex.Replace(" ", "");
txtOutputPriv.Text = "Only available when combining two private keys";
}
else
{
// Adding two public keys
ECPoint combined = pub1.GetECPoint().Add(pub2.GetECPoint());
ECPoint combinedc = ps.Curve.CreatePoint(combined.X.ToBigInteger(), combined.Y.ToBigInteger(), pub1.IsCompressedPoint);
PublicKey pkcombined = new PublicKey(combinedc.GetEncoded());
txtOutputAddress.Text = pkcombined.AddressBase58;
txtOutputPubkey.Text = pkcombined.PublicKeyHex.Replace(" ", "");
txtOutputPriv.Text = "Only available when combining two private keys";
}
}