static public CurvePoint operator +(CurvePoint a, CurvePoint b)
{
if (a.IsZero)
{
return(b);
}
if (b.IsZero)
{
return(a);
}
if (a.x == b.x && a.y != b.y)
{
return(new CurvePoint(true));
}
var m = (a == b) ? (3 * a.x * a.x + ECDSA.Curve.a) * ECDSA.Inverse(2 * a.y, ECDSA.Curve.p) :
(a.y - b.y) * ECDSA.Inverse(a.x - b.x, ECDSA.Curve.p);
var x = (m * m - a.x - b.x) % ECDSA.Curve.p;
var y = (a.y + m * (x - a.x)) % ECDSA.Curve.p;
return(new CurvePoint(x, -y));
}
static void Main(string[] args)
{
var curve = new Curve(
0,
7,
new CurvePoint(
BigInteger.Parse(
"079be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
NumberStyles.AllowHexSpecifier
),
BigInteger.Parse(
"0483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8",
NumberStyles.AllowHexSpecifier
)
),
BigInteger.Parse(
"0fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141",
NumberStyles.AllowHexSpecifier
),
1,
BigInteger.Parse(
"0fffffffffffffffffffffffffffffffffffffffffffffffffffffffefffffc2f",
NumberStyles.AllowHexSpecifier
)
);
var ecdsa = new ECDSA(256, "text.txt", curve);
var(openKey, closeKey) = ecdsa.CreateKeys();
var signature = ecdsa.CreateSignature(closeKey);
if (ecdsa.CheckSignature(signature, openKey))
{
Console.WriteLine("Signature is valid");
}
else
{
Console.WriteLine(":C");
}
}
