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The Java API provides a PRNG, the java.util.Random class. This PRNG is portable and repeatable. Consequently, two instances of the java.util.Random class that are created using the same seed will generate identical sequences of numbers in all Java implementations. Seed values are often reused on application initialization or after every system reboot. In other cases, the seed is derived from the current time obtained from the system clock. An adversary attacker can learn the value of the seed by performing some reconnaissance on the vulnerable target, and can then build a lookup table for estimating future seed values.
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