public static void SimulateMoneyExchange(BigInteger p, BigInteger q)
{
Console.WriteLine($"Bank's private p is {p}");
Console.WriteLine($"Bank's private q is {q}");
BigInteger N = p * q, phi = (p - 1) * (q - 1);
Console.WriteLine($"Bank's public N is {N}, phi(N) = {phi}");
BigInteger c, d;
CryptoTools.GenerateInverseNumbers(phi, out c, out d);
Console.WriteLine($"Bank's private c is {c} and public d is {d}");
Console.WriteLine("START OF EXCHANGE");
BigInteger n = CryptoTools.GenerateRandomBigInteger(2, N);
BigInteger r, rInv;
CryptoTools.GenerateInverseNumbers(N, out r, out rInv);
BigInteger n_ = n * CryptoTools.ModuloPower(r, d, N) % N;
Console.WriteLine("Client wants to purchase an item.");
Console.WriteLine($"Client generated private n = {n}, random r = {r}: (r, N) = 1, then calculated n_ = (n * r^d) mod N = {n_} and sent it to bank");
BigInteger s_ = CryptoTools.ModuloPower(n_, c, N);
Console.WriteLine($"Bank calculated s_ = {s_}, withdrew money from client's account and sent s_ to client");
BigInteger s = (s_ * rInv) % N;
Console.WriteLine($"Client calculated s = {s} - this is bank's signature. Client's banknote is <n = {n}, s = {s}>");
Console.WriteLine("Client sends banknote to shop");
SimulateBanknoteChecking(n, s, d, N);
Console.WriteLine("Do you want to try to use the same banknote again? y - yes, else - no");
ConsoleKeyInfo cki = Console.ReadKey();
Console.WriteLine();
if (cki.KeyChar == 'y')
{
SimulateBanknoteChecking(n, s, d, N);
}
}