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0 pointsrogers184453y ago0 comments

And it's wrong. If you initialize your own PRNG properly with multiple reseeds you saturate the entropy pool of your PRNG and subsequent reseeds are only relevant for ratcheting and state compromise proofing.

This assumes you aren't starved for entropy on initialization. If you are, it would imply a constrained environment and you are better off using getrandom() then.

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4 comments · 2 top-level

tptacek3y ago· 2 in thread

There is no such thing as being "starved for entropy", once you've hit whatever threshold you require for considering your RNG to be seeded in the first place.

rogers18445OP3y ago

If your PRNG state is is x bits, if you initialize it with less than x bits of entropy you are starved.

Since you cannot know how many bits of entropy getrandom() would give you and when it itself is reseeded with fresh entropy, you usually have your userspace PRNG sample getrandom() for some amount of time, after which it is considered initialized.

amluto3y ago

> you usually have your userspace PRNG sample getrandom() for some amount of time, after which it is considered initialized.

Who is “you”? Calling getrandom() extra times to get extra bits on the hope that the result is magically better is entirely useless.

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jepler3y ago

It was the discussion of the situation with cloned virtual machines that convinced me, not this.

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