Manikandan - 8 months ago 80

Java Question

I have an assignment on RSA implementation. Just now started working on it.

I need some ideas on random key generation. I'm clear with the theories, but not clear on how to generate those random numbers for public key and private key.

Could I get some help regarding this?

Answer Source

A Java implementation of RSA could be something similar to this:

```
import java.math.BigInteger;
import java.security.SecureRandom;
import java.util.*;
class Rsa_Implementation
{
private BigInteger n, d, e;
public Rsa_Implementation(int bitlen)
{
SecureRandom r = new SecureRandom();
BigInteger p = new BigInteger(bitlen / 2, 100, r);
BigInteger q = new BigInteger(bitlen / 2, 100, r);
n = p.multiply(q);
BigInteger m = (p.subtract(BigInteger.ONE))
.multiply(q.subtract(BigInteger.ONE));
e = new BigInteger("3");
while(m.gcd(e).intValue() > 1) e = e.add(new BigInteger("2"));
d = e.modInverse(m);
}
public BigInteger encrypt(BigInteger message)
{
return message.modPow(e, n);
}
public BigInteger decrypt(BigInteger message)
{
return message.modPow(d, n);
}
}
```