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From: Eric Sunshine <sunshine@sunshineco.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: Git List <git@vger.kernel.org>
Subject: Re: [PATCH v4 04/39] t3404: prepare 'short SHA-1 collision' tests for SHA-256
Date: Sun, 26 Jul 2020 18:31:38 -0400	[thread overview]
Message-ID: <CAPig+cS0Ap_47w+cqVipe8yD902YRO+AYStrn7mHOJQCnXuLcw@mail.gmail.com> (raw)
In-Reply-To: <20200726195424.626969-5-sandals@crustytoothpaste.net>

On Sun, Jul 26, 2020 at 3:55 PM brian m. carlson
<sandals@crustytoothpaste.net> wrote:
> The idea of the magic value "ac4f2ee" in this test is to make the
> reworded commit `collide2` have the same shortened ID as the commit
> `collide3`.
>
> To port the same idea to the SHA-256 version of Git, we therefore need
> another magic value that causes the same collision, but this time with
> the SHA-256 version of the commit IDs.
>
> In this patch, we add code guarded by `GIT_TEST_FIND_COLLIDER` to do
> exactly that. Essentially, a large number of integers is appended to the
> commit message "collide2" to find such a collision. To make it easier to
> find such a collision, we reduce the number of digits to 4.
>
> The `t/oid-info/oid` file now lists the values found in that way, and
> the test cases are modified to use those values.

This seems to be saying that t/oid-info/oid has been updated to
contain the colliding OID's generated for this test, however, those
OID's are actually specified inline in the test itself (which is the
appropriate place for them since they are specific to this test). So,
this paragraph/sentence probably ought to be dropped.

> As the tests are no longer dependent on SHA-1, we also rename their
> titles to talk about "commit IDs" instead of "SHA-1s".
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
> ---
> diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
> @@ -1262,23 +1263,54 @@ test_expect_success SHA1 'short SHA-1 setup' '
> +test_expect_success 'short commit ID collide' '
> +       test_oid_cache <<-EOF &&
> +       # collision-related constants
> +       t3404_collision sha1:6bcd
> +       t3404_collision sha256:0161
> +       t3404_collider  sha1:ac4f2ee
> +       t3404_collider  sha256:16697
> +       EOF

  reply	other threads:[~2020-07-26 22:31 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-26 19:53 [PATCH v4 00/39] SHA-256, part 3/3 brian m. carlson
2020-07-26 19:53 ` [PATCH v4 01/39] t: make test-bloom initialize repository brian m. carlson
2020-07-26 19:53 ` [PATCH v4 02/39] t1001: use $ZERO_OID brian m. carlson
2020-07-26 19:53 ` [PATCH v4 03/39] t3305: make hash agnostic brian m. carlson
2020-07-26 19:53 ` [PATCH v4 04/39] t3404: prepare 'short SHA-1 collision' tests for SHA-256 brian m. carlson
2020-07-26 22:31   ` Eric Sunshine [this message]
2020-07-26 19:53 ` [PATCH v4 05/39] t6100: make hash size independent brian m. carlson
2020-07-26 19:53 ` [PATCH v4 06/39] t6101: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 07/39] t6301: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 08/39] t6500: specify test values for SHA-256 brian m. carlson
2020-07-26 19:53 ` [PATCH v4 09/39] t6501: avoid hard-coded objects brian m. carlson
2020-07-26 19:53 ` [PATCH v4 10/39] t7003: compute appropriate length constant brian m. carlson
2020-07-26 19:53 ` [PATCH v4 11/39] t7063: make hash size independent brian m. carlson
2020-07-26 22:40   ` Eric Sunshine
2020-07-26 19:53 ` [PATCH v4 12/39] t7201: abstract away SHA-1-specific constants brian m. carlson
2020-07-26 22:54   ` Eric Sunshine
2020-07-26 19:53 ` [PATCH v4 13/39] t7102: " brian m. carlson
2020-07-26 19:53 ` [PATCH v4 14/39] t7400: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 15/39] t7405: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 16/39] t7506: avoid checking for SHA-1-specific constants brian m. carlson
2020-07-26 19:54 ` [PATCH v4 17/39] t7508: use $ZERO_OID instead of hard-coded constant brian m. carlson
2020-07-26 19:54 ` [PATCH v4 18/39] t8002: make hash size independent brian m. carlson
2020-07-26 22:49   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 19/39] t8003: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 20/39] t8011: " brian m. carlson
2020-07-26 23:00   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 21/39] t9300: abstract away SHA-1-specific constants brian m. carlson
2020-07-26 23:14   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 22/39] t9300: use $ZERO_OID instead of hard-coded object ID brian m. carlson
2020-07-26 19:54 ` [PATCH v4 23/39] t9301: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 24/39] t9350: " brian m. carlson
2020-07-26 19:54 ` [PATCH v4 25/39] t9500: ensure that algorithm info is preserved in config brian m. carlson
2020-07-26 19:54 ` [PATCH v4 26/39] t9700: make hash size independent brian m. carlson
2020-07-26 19:54 ` [PATCH v4 27/39] t5308: make test work with SHA-256 brian m. carlson
2020-07-26 19:54 ` [PATCH v4 28/39] t0410: mark test with SHA1 prerequisite brian m. carlson
2020-07-26 19:54 ` [PATCH v4 29/39] http-fetch: set up git directory before parsing pack hashes brian m. carlson
2020-07-26 23:28   ` Eric Sunshine
2020-07-26 23:30     ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 30/39] builtin/verify-pack: implement an --object-format option brian m. carlson
2020-07-26 21:29   ` Eric Sunshine
2020-07-26 22:56     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 31/39] bundle: add new version for use with SHA-256 brian m. carlson
2020-07-26 22:18   ` Eric Sunshine
2020-07-26 22:59     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 32/39] setup: add support for reading extensions.objectformat brian m. carlson
2020-07-26 23:34   ` Eric Sunshine
2020-07-26 23:41     ` brian m. carlson
2020-07-26 19:54 ` [PATCH v4 33/39] Enable SHA-256 support by default brian m. carlson
2020-07-26 23:41   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 34/39] t: add test_oid option to select hash algorithm brian m. carlson
2020-07-26 19:54 ` [PATCH v4 35/39] t: allow testing different hash algorithms via environment brian m. carlson
2020-07-26 19:54 ` [PATCH v4 36/39] t: make SHA1 prerequisite depend on default hash brian m. carlson
2020-07-26 23:52   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 37/39] ci: run tests with SHA-256 brian m. carlson
2020-07-26 23:54   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 38/39] docs: add documentation for extensions.objectFormat brian m. carlson
2020-07-26 23:56   ` Eric Sunshine
2020-07-26 19:54 ` [PATCH v4 39/39] t: remove test_oid_init in tests brian m. carlson

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