Often we might need to generate random secrets and use them in cryptographic operations when we are implementing cryptographic protocols.
For an example, I recently had to implement Zero Knowledge Protocol with Pedersen Commitment where I need to generate a random secret and convert it to a BigInteger in order to compute the pedersen commitment.
In this simple post, I thought of noting down the way I found how to do it in Java.
First, we can generate a random secret using "SecureRandom" in java. The article: "Proper Use of Java's SecureRandom" explains how to use SecureRandom properly in order to get it working in a uniform way across different platforms.
In our example, we generate the random secret by feeding a pre-defined seed - our secret - into the pseudo random number generator of the SecureRandom, so that we can generate the same random secret at a later time as well.
Next, we can convert it to a BigInteger value so that we can use it in cryptographic computations.
Following code shows how the above two steps are implemented:
For an example, I recently had to implement Zero Knowledge Protocol with Pedersen Commitment where I need to generate a random secret and convert it to a BigInteger in order to compute the pedersen commitment.
In this simple post, I thought of noting down the way I found how to do it in Java.
First, we can generate a random secret using "SecureRandom" in java. The article: "Proper Use of Java's SecureRandom" explains how to use SecureRandom properly in order to get it working in a uniform way across different platforms.
In our example, we generate the random secret by feeding a pre-defined seed - our secret - into the pseudo random number generator of the SecureRandom, so that we can generate the same random secret at a later time as well.
Next, we can convert it to a BigInteger value so that we can use it in cryptographic computations.
Following code shows how the above two steps are implemented:
import java.io.UnsupportedEncodingException;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
public class Test {
public static void main(String[] args) throws NoSuchProviderException, NoSuchAlgorithmException,
UnsupportedEncodingException {
String password = "secret";
//generate random secret using password as the seed
SecureRandom randSec = SecureRandom.getInstance("SHA1PRNG", "SUN");
randSec.setSeed(password.getBytes("us-ascii"));
//create BigInteger of length 256 from the output of the SecureRandom's pseudo random number generator
BigInteger randSecBI = new BigInteger(256, randSec);
}
}
