public virtual ECPoint ValidatePoint(BigInteger x, BigInteger y, bool withCompression)
{
ECPoint p = CreatePoint(x, y, withCompression);
if (!p.IsValid())
{
throw new ArgumentException("Invalid point coordinates");
}
return(p);
}
public virtual ECPoint ValidatePoint(BigInteger x, BigInteger y)
{
ECPoint point = this.CreatePoint(x, y);
if (!point.IsValid())
{
throw new ArgumentException("Invalid point coordinates");
}
return(point);
}
public virtual ECPoint ValidatePoint(BigInteger x, BigInteger y, bool withCompression)
{
//IL_0017: Unknown result type (might be due to invalid IL or missing references)
ECPoint eCPoint = CreatePoint(x, y, withCompression);
if (!eCPoint.IsValid())
{
throw new ArgumentException("Invalid point coordinates");
}
return(eCPoint);
}
/// <summary>
/// Hashes a seed t into a point T on the curve. Returns null if t is unsuitable.
/// </summary>
/// <param name="curve">The elliptic curve in Weierstrass form</param>
/// <param name="t">The seed</param>
/// <returns>A random point T uniquely determined by seed t, otherwise null</returns>
public static ECPoint?HashToWeierstrassCurve(ECCurve curve, byte[] t)
{
ECFieldElement x, ax, x3, y, y2;
BigInteger P = curve.Field.Characteristic;
SHA256? sha256 = SHA256.Create();
BigInteger hash = new BigInteger(sha256.ComputeHash(t));
// Check that the hash is within valid range
if (hash.CompareTo(BigInteger.One) < 0 || hash.CompareTo(P) >= 0)
{
return(null);
}
// A valid point (x,y) must satisfy: y^2 = x^3 + Ax + B mod P
// Convert hash from BigInt to FieldElement x modulo P
x = curve.FromBigInteger(hash); // x
ax = x.Multiply(curve.A); // Ax
x3 = x.Square().Multiply(x); // x^3 = x^2 * x
y2 = x3.Add(ax).Add(curve.B); // y^2 = x^3 + Ax + B
y = y2.Sqrt(); // y = sqrt(x^3 + Ax + B)
// y == null if square root mod P does not exist
if (y == null)
{
return(null);
}
ECPoint T = curve.CreatePoint(x.ToBigInteger(), y.ToBigInteger());
// Use the built-in point validator, which also checks for membership
// in weak subgroups
if (!T.IsValid())
{
return(null);
}
return(T);
}
public static ECPoint ValidatePoint(ECPoint p)
{
if (!p.IsValid())
throw new ArgumentException("Invalid point", "p");
return p;
}
