This is a tool to determine the internal seed of a java.util.Random object from a sequence of nextInt(int bound) calls. This follows the approach described by Matthew Bolan of using a change of basis on the lattice formed by plotting consecutive seeds of java.util.Random to simplify the task of finding candidate seeds to finding integer points lying between minimum and maximum coordinates.
In random_reverser.sage, either set bound to the desired value if all RNG calls use the same bound, or set the components of the bounds vector to the individual bounds of each RNG call if the calls use different bounds. (All bounds must be powers of two.)
Run the RNG reverser by entering the following on the command line:
$ sage random_reverser.sage
The sequence of RNG call results should be entered into the program's standard input.
The program RNG.java provides a sample sequence of RNG call results to be piped into the RNG cracker for testing purposes.
This program was primarily an excercise in understanding how reversing java.util.Random works, and is limited in its usefulness. If you need to reverse java.util.Random yourself, I would highly recommend LattiCG instead.