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From: Carlo Arenas <carenas@gmail.com>
To: Jeff King <peff@peff.net>
Cc: "brian m. carlson" <sandals@crustytoothpaste.net>,
	rsbecker@nexbridge.com, git@vger.kernel.org
Subject: Re: [PATCH 1/2] wrapper: add a helper to generate numbers from a CSPRNG
Date: Tue, 16 Nov 2021 19:36:51 -0800	[thread overview]
Message-ID: <CAPUEsphh-enSYS66mi7_XaS0n1bmUvGXRcgVp6iqhg94xSHVog@mail.gmail.com> (raw)
In-Reply-To: <YZRxOrv9JFt2oeSU@coredump.intra.peff.net>

On Tue, Nov 16, 2021 at 7:04 PM Jeff King <peff@peff.net> wrote:
>
> On Tue, Nov 16, 2021 at 05:50:44PM -0800, Carlo Arenas wrote:
>
> > for the little amount of random data we need, it might be wiser to
> > fallback to something POSIX like lrand48 which is most likely to be
> > available, but of course your tests that consume lots of random data
> > will need to change.
>
> Unfortunately that won't help. You have to seed lrand48 with something,
> which usually means pid and/or timestamp. Which are predictable to an
> attacker, which was the start of the whole conversation. You really need
> _some_ source of entropy, and only the OS can provide that.

again, showing my ignorance here; but that "something" doesn't need to
be guessable externally; ex: git add could use as seed contents from
the file that is adding, or even better mix it up with the other
sources as a poor man's /dev/urandom

I agree though that having a true random source will require the OS,
but isn't it about generating 6 random letters?

Carlo

  parent reply	other threads:[~2021-11-17  3:37 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-16  3:35 [PATCH 0/2] Generate temporary files using a CSPRNG brian m. carlson
2021-11-16  3:35 ` [PATCH 1/2] wrapper: add a helper to generate numbers from " brian m. carlson
2021-11-16 15:31   ` Jeff King
2021-11-16 16:01     ` rsbecker
2021-11-16 18:22       ` Taylor Blau
2021-11-16 19:58         ` rsbecker
2021-11-16 22:41       ` brian m. carlson
2021-11-16 23:20         ` rsbecker
2021-11-17  0:47           ` Carlo Arenas
2021-11-17  3:05             ` rsbecker
2021-11-17  1:03           ` brian m. carlson
2021-11-17  1:50             ` Carlo Arenas
2021-11-17  3:04               ` Jeff King
2021-11-17  3:12                 ` rsbecker
2021-11-17  3:36                 ` Carlo Arenas [this message]
2021-11-17 20:01                   ` Jeff King
2021-11-17 20:19                     ` rsbecker
2021-11-17 23:30                       ` brian m. carlson
2021-11-17 23:34                         ` rsbecker
2021-11-17  3:03             ` rsbecker
2021-11-17  7:39   ` Junio C Hamano
2021-11-17 23:01     ` brian m. carlson
2021-11-18  7:19       ` Junio C Hamano
2021-11-18 22:16         ` brian m. carlson
2021-11-22  9:10           ` Junio C Hamano
2021-11-16  3:35 ` [PATCH 2/2] wrapper: use a CSPRNG to generate random file names brian m. carlson
2021-11-16 15:36   ` Jeff King
2021-11-16 18:28     ` Taylor Blau
2021-11-16 18:57       ` Junio C Hamano
2021-11-16 19:21         ` Jeff King
2021-11-16 19:33           ` Taylor Blau
2021-11-16 15:44 ` [PATCH 0/2] Generate temporary files using a CSPRNG Jeff King
2021-11-16 22:17   ` brian m. carlson
2021-11-16 22:29     ` rsbecker
2021-11-16 20:35 ` Ævar Arnfjörð Bjarmason
2021-11-16 21:06   ` Jeff King
2021-11-17  8:36     ` Ævar Arnfjörð Bjarmason

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