public int Encrypt(int p, int q, int M, int e)
{
// Get n
long n = p * q;
NumberTheory calc = new NumberTheory();
// Get C = M^e mod n
int C = (int)calc.FastPower(M, e, n);
return(C);
}
public List <int> GetKeys(int q, int alpha, int xa, int xb)
{
NumberTheory calc = new NumberTheory();
// q: prime number
// alpha: primitive root of q
// UserA Key Generation
long ya = calc.FastPower(alpha, xa, q);
// UserB Key Generation
long yb = calc.FastPower(alpha, xb, q);
List <int> keys = new List <int>
{
// Secret Key by User A
(int)(calc.FastPower(yb, xa, q)),
// Secret Key by User B
(int)(calc.FastPower(ya, xb, q))
};
return(keys);
}
public int Decrypt(int p, int q, int C, int e)
{
long n = p * q;
// Get phi(n)
// Call Euclidean Extended to get d
NumberTheory calc = new NumberTheory();
long d = calc.GetMultiplicativeInverse(e, calc.Phi(p, q));
// Get M = C^d mod d
int M = (int)calc.FastPower(C, d, n);
return(M);
}