public static Secp256k1FieldElement GetYCoordinate(Secp256k1FieldElement x, bool yIsEven)
{
var a = Secp256k1Constants.A;
var b = Secp256k1Constants.B;
// y^2 == x^3 + a*x + b
var left = x.Pow(3) + a * x + b;
var leftField = new Secp256k1FieldElement(left.Num);
var candidateY = leftField.Sqrt();
Secp256k1FieldElement even;
Secp256k1FieldElement odd;
if (candidateY.Num % 2 == 0)
{
even = candidateY;
odd = new Secp256k1FieldElement(Secp256k1Constants.P - candidateY.Num);
}
else
{
even = new Secp256k1FieldElement(Secp256k1Constants.P - candidateY.Num);
odd = candidateY;
}
if (yIsEven)
{
return(even);
}
else
{
return(odd);
}
}
public Secp256k1Point(Secp256k1FieldElement x, Secp256k1FieldElement y) : base(Secp256k1Constants.A, Secp256k1Constants.B, x, y)
{
}
