[Cryptography] [FORGED] Re: OpenSSL and random

[Peter Gutmann]

Bill Cox <waywardgeek at gmail.com> writes:


>"A read from the /dev/urandom device will not block waiting for more entropy.
>As a result,  if  there is  not sufficient entropy in the entropy pool, the
>returned values are theoretically vulnerable to a cryptographic attack on the
>algorithms used by the driver."

That's taking a very narrow view of the world.  If you step back a bit from
the hardcore-crypto-geek perspective and adopt a more general view,
/dev/random would need a warning:

"A read from the /dev/urandom device will block waiting for more entropy. This
means your application will appear to hang/crash at random intervals, leading
to hard-to-diagnose faults, customer complaints, loss of business, and, if
you're really unlucky, lawsuits".

So you've got a table that looks roughly like this:

  Geek                                     Normal human
  ----                                     ------------
  App.blocks waiting for entropy           App doesn't work
  App doesn't block on entropy             App works

>From which the conclusion is obvious: Don't ever stop waiting for entropy to
appear.

Peter.

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