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Groups > comp.lang.python > #7187

Re: How good is security via hashing

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On Tue, 07 Jun 2011 13:27:59 +0100, Robin Becker wrote:

>> If you want the full 16 bytes of unpredictability, why don't you just
>> read 16 bytes from
>> /dev/urandom and forget about all the other stuff?
>
> I have a vague memory that the original author felt that entropy might
> run out or something like that so reading from /dev/urandom always was
> not a good idea.

The problem with /dev/urandom is that it shares the same entropy pool as
/dev/random, so you're "stealing" entropy which may be needed for tasks
which really need it (e.g. generating SSL/TLS keys).

Personally, I'd take whatever "cheap" entropy I can get and hash it.
If you're going to read from /dev/urandom, limit it to a few bytes per
minute, not per request.

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How good is security via hashing Robin Becker <robin@reportlab.com> - 2011-06-07 11:18 +0100
  Re: How good is security via hashing Jean-Paul Calderone <calderone.jeanpaul@gmail.com> - 2011-06-07 04:40 -0700
    Re: How good is security via hashing Robin Becker <robin@reportlab.com> - 2011-06-07 13:27 +0100
      Re: How good is security via hashing Paul Rubin <no.email@nospam.invalid> - 2011-06-07 06:00 -0700
      Re: How good is security via hashing Nobody <nobody@nowhere.com> - 2011-06-07 22:23 +0100
        Re: How good is security via hashing Paul Rubin <no.email@nospam.invalid> - 2011-06-07 19:38 -0700
          Re: How good is security via hashing Nobody <nobody@nowhere.com> - 2011-06-08 08:18 +0100
            Re: How good is security via hashing Paul Rubin <no.email@nospam.invalid> - 2011-06-08 00:40 -0700

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