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Date: Sun, 1 Sep 2013 14:12:27 +0100
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To: "Bryan C. Geraghty" <bryan@ravensight.org>
Cc: Marc Bennewitz <php@marc-bennewitz.de>, PHP internals list <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=047d7b2e15c511bbbb04e552355d
Subject: Re: [PHP-DEV] More powerful (and backward compatible) API of random
 number generator functions
From: bukka@php.net (Jakub Zelenka)

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Content-Type: text/plain; charset=ISO-8859-1

Hi,

I ask this because the OpenSSL option here is the only CSPRNG; The others
> are trivially breakable and should not be used for cryptographic
> applications. I could see an argument for wanting to use them in
> non-security contexts but I'm wondering if the API should make it clear
> when that is being done.
>

if you mean openssl_random_pseudo_bytes, then it's not CSPRNG because it
calls RAND_pseudo_bytes. You would have to use RAND_bytes to have CSPRNG
but then you would have to seeded before calling. See
http://www.openssl.org/docs/crypto/RAND_bytes.html and OpenSSL sources for
more details.

I don't think that using OpenSSL here is a good idea. There should be a
better framework or new functions for dealing with OpenSSL Rand but that's
a bit off topic...

The whole proposal is a bit confusing for me. The combination of PRNG
algorithm (MT) with libraries (libc, OpenSSL, GMP) that implements one or
more PRNG algorithms just doesn't make sense to me. It doesn't say anything
about the speed and crypto strength of the algorithms. I think that much
better solution would be an extension that implements a couple of
algorithms. Then you could select what algorithm you want to use. The good
idea would be to have some reasonable default algorithm that would be used
if the user doesn't know anything about algorithms. This could be
implemented as an extension and if it's good enough then it could be
proposed as the core addition.

Jakub

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