musl - Re: [PATCH] Add support for mkostemp, mkstemps and mkostemps

Date: Sat, 2 Feb 2013 23:11:11 +0100
From: Szabolcs Nagy <nsz@...t70.net>
To: musl@...ts.openwall.com
Subject: Re: [PATCH] Add support for mkostemp, mkstemps and mkostemps

* John Spencer <maillist-musl@...fooze.de> [2013-02-02 20:51:12 +0100]:
> +	unsigned long r = ts.tv_nsec + (uintptr_t)&ts / 16 + (uintptr_t)x6;

i recommend a multiplier here, eg. with

r = nsec*1664525 + A;

if only the last few bits of nsec are uniform random then
the top bits of A are not immediately known from r

..only the top bits of A*4276115653 can be known
(1664525*4276115653 == 1 mod 2^32)

and that's probably less useful for an attacker

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