Java

Generating Repeatable Random Data for Testing/Debugging

See more PRNG Examples

Demonstrates how to use the Fortuna PRNG to generate random-looking but repeatable non-random data for the purpose of testing and debugging. Chilkat2 Java

import com.chilkatsoft.chilkat2.Prng;

public class ChilkatExample {

    public static void main(String[] args) {
        boolean success = false;

        // This example assumes the Chilkat API to have been previously unlocked.
        // See Global Unlock Sample for sample code.

        success = false;

        Prng fortuna = new Prng();

        // Normally an application would seed the PRNG with entropy from
        // some real random source.  However, sometimes we want the same
        // random sequence of bytes for testing and debugging purposes.
        // This a reason why GetEntropy and AddEntropy are two different methods.
        // An application could omit the call to GetEntropy, and instead pass
        // non-random data to AddEntropy. For example:

        // Seed the PRNG with non-entropy, so we get a repeatable sequence.
        // Note: AddEntropy can be called any number of times.
        fortuna.addEntropy("01020304", "hex");
        fortuna.addEntropy("hello world", "ascii");

        // Generate some random data:
        String strRandHex = fortuna.genRandom(16, "hex");
        String strRandBase64 = fortuna.genRandom(22, "base64");
        String strRandBase58 = fortuna.genRandom(32, "base58");

        System.out.println("hex random bytes: " + strRandHex);
        System.out.println("base64 random bytes: " + strRandBase64);
        System.out.println("base58 random bytes: " + strRandBase58);

        // Try it again with a different object to verify that the same results are obtained:
        Prng fortuna2 = new Prng();

        fortuna2.addEntropy("01020304", "hex");
        fortuna2.addEntropy("hello world", "ascii");

        strRandHex = fortuna2.genRandom(16, "hex");
        strRandBase64 = fortuna2.genRandom(22, "base64");
        strRandBase58 = fortuna2.genRandom(32, "base58");

        System.out.println("hex random bytes: " + strRandHex);
        System.out.println("base64 random bytes: " + strRandBase64);
        System.out.println("base58 random bytes: " + strRandBase58);
    }
}