public static BigInteger ModInverse(BigInteger bi, BigInteger modulus)
{
if (modulus._length == 1)
{
return(ModInverse(bi, modulus._data[0]));
}
BigInteger[] p = { 0, 1 };
var q = new BigInteger[2]; // quotients
BigInteger[] r = { 0, 0 }; // remainders
var step = 0;
var a = modulus;
var b = bi;
var mr = new ModulusRing(modulus);
while (b != 0)
{
if (step > 1)
{
var pval = mr.Difference(p[0], p[1] * q[0]);
p[0] = p[1];
p[1] = pval;
}
var divret = MultiByteDivide(a, b);
q[0] = q[1];
q[1] = divret[0];
r[0] = r[1];
r[1] = divret[1];
a = b;
b = divret[1];
step++;
}
if (r[0] != 1)
{
throw (new ArithmeticException("No inverse!"));
}
return(mr.Difference(p[0], p[1] * q[0]));
}
public BigInteger ModPow(BigInteger exp, BigInteger n)
{
var mr = new ModulusRing(n);
return(mr.Pow(this, exp));
}
public BigInteger ModPow(BigInteger exp, BigInteger n)
{
var mr = new ModulusRing(n);
return mr.Pow(this, exp);
}
public static BigInteger modInverse(BigInteger bi, BigInteger modulus)
{
if (modulus.length == 1) return modInverse(bi, modulus.data[0]);
BigInteger[] p = { 0, 1 };
var q = new BigInteger[2]; // quotients
BigInteger[] r = { 0, 0 }; // remainders
int step = 0;
BigInteger a = modulus;
BigInteger b = bi;
var mr = new ModulusRing(modulus);
while (b != 0)
{
if (step > 1)
{
BigInteger pval = mr.Difference(p[0], p[1] * q[0]);
p[0] = p[1];
p[1] = pval;
}
BigInteger[] divret = multiByteDivide(a, b);
q[0] = q[1];
q[1] = divret[0];
r[0] = r[1];
r[1] = divret[1];
a = b;
b = divret[1];
step++;
}
if (r[0] != 1)
throw (new ArithmeticException("No inverse!"));
return mr.Difference(p[0], p[1] * q[0]);
}
