public BigInt ModInv(BigInt p, BigInt negP)
{
var u = this.Clone();
var v = p.Clone();
var x1 = new BigInt(1, p.Length);
var x2 = new BigInt(0, p.Length);
while (!u.IsOne() && !v.IsOne())
{
while (u.IsEven())
{
u.Div2Trunc();
x1.Div2(p);
}
while (v.IsEven())
{
v.Div2Trunc();
x2.Div2(p);
}
if (u >= v)
{
var uTmp = u;
u = u.SubMod(v, p, negP);
uTmp.Clear();
var x1Tmp = x1;
x1 = x1.SubMod(x2, p, negP);
x1Tmp.Clear();
}
else
{
var vTmp = v;
v = v.SubMod(u, p, negP);
vTmp.Clear();
var x2Tmp = x2;
x2 = x2.SubMod(x1, p, negP);
x2Tmp.Clear();
}
}
v.Clear();
if (u.IsOne())
{
u.Clear();
x2.Clear();
return(x1);
}
else
{
u.Clear();
x1.Clear();
return(x2);
}
}