From: "brian m. carlson" <sandals@crustytoothpaste•net>
To: <git@vger•kernel.org>
Cc: Junio C Hamano <gitster@pobox•com>, Patrick Steinhardt <ps@pks•im>
Subject: [PATCH v3 3/9] docs: reflect actual double signature for tags
Date: Thu, 9 Oct 2025 21:56:20 +0000 [thread overview]
Message-ID: <20251009215626.3089287-4-sandals@crustytoothpaste.net> (raw)
In-Reply-To: <20251009215626.3089287-1-sandals@crustytoothpaste.net>
The documentation for the hash function transition reflects the original
design where the SHA-256 signature would always be placed in a header.
However, due to a missed patch in Git 2.29, we shipped SHA-256 support
such that the signature for the current algorithm is always an in-body
signature and the opposite algorithm is always in a header. Since the
documentation is inaccurate, update it to reflect the correct
information.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste•net>
---
.../technical/hash-function-transition.adoc | 20 ++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/Documentation/technical/hash-function-transition.adoc b/Documentation/technical/hash-function-transition.adoc
index adb0c61e53..2359d7d106 100644
--- a/Documentation/technical/hash-function-transition.adoc
+++ b/Documentation/technical/hash-function-transition.adoc
@@ -429,17 +429,19 @@ ordinary unsigned commit.
Signed Tags
~~~~~~~~~~~
-We add a new field "gpgsig-sha256" to the tag object format to allow
-signing tags without relying on SHA-1. Its signed payload is the
-SHA-256 content of the tag with its gpgsig-sha256 field and "-----BEGIN PGP
-SIGNATURE-----" delimited in-body signature removed.
+We add new fields "gpgsig" and "gpgsig-sha256" to the tag object format to
+allow signing tags in both formats. The in-body signature is used for the
+signature in the current hash algorithm and the header is used for the
+signature in the other algorithm. Thus, a dual-signature tag will contain both
+an in-body signature and a gpgsig-sha256 header for the SHA-1 format of an
+object or both an in-body signature and a gpgsig header for the SHA-256 format
+of and object.
-This means tags can be signed
+The signed payload of the tag is the content of the tag in the current
+algorithm with both its gpgsig and gpgsig-sha256 fields and
+"-----BEGIN PGP SIGNATURE-----" delimited in-body signature removed.
-1. using SHA-1 only, as in existing signed tag objects
-2. using both SHA-1 and SHA-256, by using gpgsig-sha256 and an in-body
- signature.
-3. using only SHA-256, by only using the gpgsig-sha256 field.
+This means tags can be signed using one or both algorithms.
Mergetag embedding
~~~~~~~~~~~~~~~~~~
next prev parent reply other threads:[~2025-10-09 21:56 UTC|newest]
Thread overview: 67+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-19 1:09 [PATCH 0/9] SHA-1/SHA-256 interoperability, part 1 brian m. carlson
2025-09-19 1:09 ` [PATCH 1/9] docs: update pack index v3 format brian m. carlson
2025-09-19 22:08 ` Junio C Hamano
2025-09-20 15:23 ` brian m. carlson
2025-09-20 17:01 ` Junio C Hamano
2025-09-24 7:55 ` Patrick Steinhardt
2025-09-25 21:39 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 2/9] docs: update offset order for pack index v3 brian m. carlson
2025-09-19 1:09 ` [PATCH 3/9] docs: reflect actual double signature for tags brian m. carlson
2025-09-19 22:34 ` Junio C Hamano
2025-09-20 15:29 ` brian m. carlson
2025-09-20 17:04 ` Junio C Hamano
2025-09-24 7:55 ` Patrick Steinhardt
2025-09-25 21:46 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 4/9] docs: improve ambiguous areas of pack format documentation brian m. carlson
2025-09-19 23:04 ` Junio C Hamano
2025-09-19 1:09 ` [PATCH 5/9] docs: add documentation for loose objects brian m. carlson
2025-09-19 19:10 ` Junio C Hamano
2025-09-19 19:13 ` Junio C Hamano
2025-09-19 19:15 ` brian m. carlson
2025-09-19 20:18 ` Junio C Hamano
2025-09-24 7:55 ` Patrick Steinhardt
2025-09-25 21:40 ` brian m. carlson
2025-09-19 23:16 ` Junio C Hamano
2025-09-24 7:55 ` Patrick Steinhardt
2025-09-30 16:39 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 6/9] rev-parse: allow printing compatibility hash brian m. carlson
2025-09-19 23:24 ` Junio C Hamano
2025-09-24 7:55 ` Patrick Steinhardt
2025-09-25 21:48 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 7/9] fsck: consider gpgsig headers expected in tags brian m. carlson
2025-09-19 23:31 ` Junio C Hamano
2025-09-22 21:38 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 8/9] Allow specifying compatibility hash brian m. carlson
2025-09-24 7:56 ` Patrick Steinhardt
2025-09-30 16:44 ` brian m. carlson
2025-09-19 1:09 ` [PATCH 9/9] t: add a prerequisite for a " brian m. carlson
2025-09-24 7:56 ` Patrick Steinhardt
2025-10-02 22:38 ` [PATCH v2 0/9] SHA-1/SHA-256 interoperability, part 1 brian m. carlson
2025-10-02 22:38 ` [PATCH v2 1/9] docs: update pack index v3 format brian m. carlson
2025-10-03 17:00 ` Junio C Hamano
2025-10-02 22:38 ` [PATCH v2 2/9] docs: update offset order for pack index v3 brian m. carlson
2025-10-02 22:38 ` [PATCH v2 3/9] docs: reflect actual double signature for tags brian m. carlson
2025-10-02 22:38 ` [PATCH v2 4/9] docs: improve ambiguous areas of pack format documentation brian m. carlson
2025-10-03 17:07 ` Junio C Hamano
2025-10-03 21:06 ` brian m. carlson
2025-10-02 22:38 ` [PATCH v2 5/9] docs: add documentation for loose objects brian m. carlson
2025-10-03 17:05 ` Junio C Hamano
2025-10-02 22:38 ` [PATCH v2 6/9] rev-parse: allow printing compatibility hash brian m. carlson
2025-10-02 22:38 ` [PATCH v2 7/9] fsck: consider gpgsig headers expected in tags brian m. carlson
2025-10-02 22:38 ` [PATCH v2 8/9] t: allow specifying compatibility hash brian m. carlson
2025-10-03 17:14 ` Junio C Hamano
2025-10-03 20:45 ` brian m. carlson
2025-10-02 22:38 ` [PATCH v2 9/9] t1010: use BROKEN_OBJECTS prerequisite brian m. carlson
2025-10-09 21:56 ` [PATCH v3 0/9] SHA-1/SHA-256 interoperability, part 1 brian m. carlson
2025-10-09 21:56 ` [PATCH v3 1/9] docs: update pack index v3 format brian m. carlson
2025-10-09 21:56 ` [PATCH v3 2/9] docs: update offset order for pack index v3 brian m. carlson
2025-10-09 21:56 ` brian m. carlson [this message]
2025-10-09 21:56 ` [PATCH v3 4/9] docs: improve ambiguous areas of pack format documentation brian m. carlson
2025-10-09 21:56 ` [PATCH v3 5/9] docs: add documentation for loose objects brian m. carlson
2025-10-09 21:56 ` [PATCH v3 6/9] rev-parse: allow printing compatibility hash brian m. carlson
2025-10-09 21:56 ` [PATCH v3 7/9] fsck: consider gpgsig headers expected in tags brian m. carlson
2025-10-09 21:56 ` [PATCH v3 8/9] t: allow specifying compatibility hash brian m. carlson
2025-10-09 21:56 ` [PATCH v3 9/9] t1010: use BROKEN_OBJECTS prerequisite brian m. carlson
2025-10-13 15:24 ` [PATCH v3 0/9] SHA-1/SHA-256 interoperability, part 1 Junio C Hamano
2025-10-13 16:34 ` brian m. carlson
2025-10-14 5:53 ` Patrick Steinhardt
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