prng-lattice-lab: recoverability of java.util.Random under partial-state leakage

A closed, offline research harness that maps the recoverability boundary of java.util.Random under partial-state leakage, anchored on the Randar (Minecraft) truncated-LCG attack and generalised to a (bits-leaked-per-call × observations) phase diagram. Complete solvers cover the top-bits, nextInt(odd-bound), bit-length, and truncated-MT19937 leak models; recovery demonstrations are reproducible, self-verifying, and can run against a real OpenJDK.

Demonstrated vs. generalized: what is demonstrated is state recovery from the stated observations of a generator the lab instantiates itself (e.g. the published Randar vector; the recorded phase-diagram cells; the lab model matching a live OpenJDK over sampled states). It is not a claim that any specific deployed system exposes those observations across a trust boundary. It attacks no live target and no third-party system.