Messages in this thread |  | | Subject | Re: /dev/random broken? | From | Valdis.Kletnieks@vt ... | Date | Sat, 28 Jun 2003 22:36:04 -0400 |
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On Sat, 28 Jun 2003 19:10:18 PDT, Justin Pryzby said: > /dev/urandom is what you want; it makes up its own entropy. /dev/random > uses entropy from user input (low order bits I imagine).
Strictly speaking, urandom doesn't "make up" any entropy - it generates a pseudorandom stream of bits of arbitrary length using a small chunk of entropy from the entropy pool. That's why it's able to generate multi-megabyte streams of bits even when the entropy pool is empty - it is generating a fixed but unpredictable stream based on the initial entropy.
The distinction is important mostly to cryptographers - for almost all practical uses, the pseudorandom stream of bits produced by urandom is quite sufficient, much faster, and leaves the entropy pool untouched for those applications that *do* care about the difference.... [unhandled content-type:application/pgp-signature] |  |