public BigInteger Decrypt(BigInteger codedMessage)
{
//return ChineseRemainderTheorem.Solve(codedMessage, D, P, Q);
return(FastModExponentiation.DoModPow(codedMessage, D, N));
}
public static bool IsPrime(BigInteger number)
{
// handle evens
if (number == 2)
{
return(true);
}
else if (number % 2 == 0)
{
return(false);
}
// get S
var S = 1;
while (((number - 1) % BigInteger.Pow(2, ++S)) == 0)
{
;
}
S--;
// get d
var d = (number - 1) / BigInteger.Pow(2, S);
//Console.WriteLine($"{S}, {d}");
Random rnd = new Random();
int randomBase;
// repeat 8 times to be sure :)
for (int i = 0; i < 8; i++)
{
// get random base that meets gcd(b,n)=1 condition
do
{
randomBase = rnd.Next();
} while (Euclidean.Simple(randomBase, number) != 1);
if (FastModExponentiation.DoModPow(randomBase, d, number) != 1)
{
bool existR = false;
for (int r = 0; r < S; r++)
{
if (FastModExponentiation.DoModPow(randomBase, d * (BigInteger.Pow(2, r)), number) == number - 1)
{
existR = true;
break;
}
}
if (existR)
{
continue;
}
}
else
{
continue;
}
return(false);
}
return(true);
}
public BigInteger Encrypt(BigInteger message)
{
//return ChineseRemainderTheorem.Solve(message, E, P, Q);
return(FastModExponentiation.DoModPow(message, E, N));
}