PointGFp::PointGFp(const CurveGFp& curve) :
curve(curve), ws(2 * (curve.get_p_words() + 2))
{
coord_x = 0;
coord_y = monty_mult(1, curve.get_r2());
coord_z = 0;
}
PointGFp::PointGFp(const CurveGFp& curve, const BigInt& x, const BigInt& y) :
curve(curve), ws(2 * (curve.get_p_words() + 2))
{
coord_x = monty_mult(x, curve.get_r2());
coord_y = monty_mult(y, curve.get_r2());
coord_z = monty_mult(1, curve.get_r2());
}
PointGFp::PointGFp(const CurveGFp& curve, const BigInt& x, const BigInt& y) :
m_curve(curve),
m_coord_x(x),
m_coord_y(y),
m_coord_z(1)
{
if(x <= 0 || x >= curve.get_p())
throw Invalid_Argument("Invalid PointGFp affine x");
if(y <= 0 || y >= curve.get_p())
throw Invalid_Argument("Invalid PointGFp affine y");
m_curve.to_rep(m_coord_x, m_monty_ws);
m_curve.to_rep(m_coord_y, m_monty_ws);
m_curve.to_rep(m_coord_z, m_monty_ws);
}
PointGFp OS2ECP(const uint8_t data[], size_t data_len,
const CurveGFp& curve)
{
// Should we really be doing this?
if(data_len <= 1)
return PointGFp(curve); // return zero
std::pair<BigInt, BigInt> xy = OS2ECP(data, data_len, curve.get_p(), curve.get_a(), curve.get_b());
PointGFp point(curve, xy.first, xy.second);
if(!point.on_the_curve())
throw Illegal_Point("OS2ECP: Decoded point was not on the curve");
return point;
}
