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In this noncompliant code example described by [Wang 2012], the process ID, time of day, and uninitialized memory junk is used to seed a random number generator. This behavior is characteristic of some distributions derived from Debian that use uninitialized memory as a source of entropy because the value stored in junk is indeterminate. However, because accessing indeterminate values is undefined behavior, compilers may optimize out the uninitialized variable access completely, leaving only the time and process ID and resulting in a loss of desired entropy.
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In security protocols that rely on unpredictability, such as RSA encryption, a loss in entropy results in a less secure system [Wang 2012].
Compliant Solution (POSIX, Entropy)
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