A python script and class that exploits the deterministic nature of java.util.Random() for two simple cases.
The script/class is based on java.util.Random algorithms and values. For other packages you would have to adjust the MULT / ADD / MASK values manually. Depending on the algorithms used additional manual changes would be necessary.
Case 1: a long (64bit) rnd number is known. NotSoRandom() allows to calculate the seed and either previous and next long rnd values based on the found seed.
Case 2: two sequentially calculated rnd int numbers are known. NotSoRandom() allows to calculate the seed and either previous and next int rnd values based on the found seed.
An example script 'get_previous_long.py' is provided that illustrates the usage of class NotSoRandom.