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. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

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

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

    success = false;

    CkPrng fortuna = new CkPrng();

    // 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.
    success = fortuna.AddEntropy("01020304","hex");
    success = 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:
    CkPrng fortuna2 = new CkPrng();

    success = fortuna2.AddEntropy("01020304","hex");
    success = 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);
  }
}