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From: "Dmitry V. Levin" <>
Subject: Re: [devel] hash collision in rpm
Date: Wed, 5 May 2021 16:10:04 +0300
Message-ID: <> (raw)
In-Reply-To: <>

On Wed, May 05, 2021 at 08:40:27AM +0300, Alexey Tourbin wrote:
> By the way, there's a clever way to detect collisions at a higher
> level, even though low-level collisions are unavoidable, subject to
> implacable math. We can take advantage of the fact that the build
> system synchronizes package builds across a few architectures.
> Currently, if a missing symbol goes undetected due to a hash
> collision, it does so on all architectures simultaneously. To change
> that, we need to hash symbols differently, depending on the target
> architecture (we can pass seed=hash(arch) to the hash function, or use
> different initialization vectors IV=hash(arch)).  The desired outcome
> is that when a missing symbol goes undetected, it does so, with an
> overwhelming probability, on only one target.  Roughly speaking, if
> the probability of an undetected missing symbol is 10^-3 on a single
> target, it must be 10^-6 on two targets, 10^-9 on thee targets, etc.

This looks very promising indeed.  I suppose the gain would justify
the necessary rebuilding of all packages with set-versions in their
arch-specific dependencies.


  reply	other threads:[~2021-05-05 13:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-01  9:04 ` [devel] rust-1:1.50.0-alt1: Sisyphus/x86_64 test rebuild failed Alexey Gladkov
2021-05-04 10:32   ` [devel] hash collision in rpm Anton Farygin
2021-05-04 10:45     ` Alexey Gladkov
2021-05-04 12:50       ` Alexey Tourbin
2021-05-05  5:40         ` Alexey Tourbin
2021-05-05 13:10           ` Dmitry V. Levin [this message]
2021-05-05 14:11           ` Vladimir D. Seleznev

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