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/**
*
*/
/**
* @author sven
*
*/
import java.math.*;
import java.util.Random;
public class KryptArith {
char bottomChar='~';
char topChar='!';
int bottomInt=(int) bottomChar;
int topInt=(int) topChar;
public BigInteger modInv(BigInteger a, BigInteger b)
{
BigInteger r1 = new BigInteger("0");
BigInteger r2 = new BigInteger("1");
BigInteger a_new = new BigInteger("0");
BigInteger b_new = new BigInteger("0");
BigInteger r1_new = BigInteger.ZERO;
BigInteger r2_new = BigInteger.ZERO;
while (b.compareTo(BigInteger.ONE) != 0)
{
a_new=b;
try
{
b_new=a.mod(b);
}
catch (Exception e)
{
System.out.println("No Inverse "+e);
//System.exit(1);
return BigInteger.ZERO.subtract(BigInteger.ONE);
}
r1_new = r2;
r2_new=r1.subtract(r2.multiply(a.divide(b)));
a=a_new;
b=b_new;
r1=r1_new;
r2=r2_new;
}
return r2;
}
public int modInv(int a, int b) throws Exception
{
int r1 = 1;
int r2 = 0;
int r1_new = 1;
int r2_new = 0;
int a_new = 0;
int b_new = 0;
while (b_new != 1)
{
a_new=b;
/*try
{
b_new=a % b;
}
catch (Exception e)
{
//System.out.println("No Inverse "+e);
//System.exit(1);
return -1;
}*/
b_new=a % b;
r1_new = r2;
r2_new = r1 - ((a / b) * r2);
a=a_new;
b=b_new;
r1=r1_new;
r2=r2_new;
}
return r2;
}
public int gcd(int a, int b)
{
if (b==0) return a;
return gcd(b,a%b);
}
public BigInteger gcd(BigInteger a, BigInteger b)
{
if (b.compareTo(BigInteger.ZERO) == 0) return a;
return gcd(b,a.mod(b));
}
public static int gen8bitPrim() {
Random rnd = new Random();
return BigInteger.probablePrime(8, rnd).intValue();
}
}
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