* [PATCH 0/2] document signature formats @ 2014-10-22 15:16 Michael J Gruber 2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber 2014-10-22 15:16 ` [PATCH 2/2] Documentation/technical: document push certificate format Michael J Gruber 0 siblings, 2 replies; 9+ messages in thread From: Michael J Gruber @ 2014-10-22 15:16 UTC (permalink / raw) To: git This is a first shot at documenting the various signatures that we use in a technical document. If something like this is deemed useful I should probably recreate the sample signatures using our testlib keys and users in a v2. Michael J Gruber (2): Documentation/technical: signature formats Documentation/technical: document push certificate format Documentation/Makefile | 1 + Documentation/technical/signature-format.txt | 161 +++++++++++++++++++++++++++ 2 files changed, 162 insertions(+) create mode 100644 Documentation/technical/signature-format.txt -- 2.1.2.756.gfa53a0a ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 1/2] Documentation/technical: signature formats 2014-10-22 15:16 [PATCH 0/2] document signature formats Michael J Gruber @ 2014-10-22 15:16 ` Michael J Gruber 2014-10-22 16:57 ` Jakub Narębski 2014-10-22 19:02 ` Junio C Hamano 2014-10-22 15:16 ` [PATCH 2/2] Documentation/technical: document push certificate format Michael J Gruber 1 sibling, 2 replies; 9+ messages in thread From: Michael J Gruber @ 2014-10-22 15:16 UTC (permalink / raw) To: git Various formats for storing signatures have accumulated by now. Document them to keep track (and maybe avoid yet another one). Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> --- Documentation/Makefile | 1 + Documentation/technical/signature-format.txt | 126 +++++++++++++++++++++++++++ 2 files changed, 127 insertions(+) create mode 100644 Documentation/technical/signature-format.txt diff --git a/Documentation/Makefile b/Documentation/Makefile index cea0e7a..2638c0c 100644 --- a/Documentation/Makefile +++ b/Documentation/Makefile @@ -74,6 +74,7 @@ TECH_DOCS += technical/protocol-common TECH_DOCS += technical/racy-git TECH_DOCS += technical/send-pack-pipeline TECH_DOCS += technical/shallow +TECH_DOCS += technical/signature-format TECH_DOCS += technical/trivial-merge SP_ARTICLES += $(TECH_DOCS) SP_ARTICLES += technical/api-index diff --git a/Documentation/technical/signature-format.txt b/Documentation/technical/signature-format.txt new file mode 100644 index 0000000..80f0a47 --- /dev/null +++ b/Documentation/technical/signature-format.txt @@ -0,0 +1,126 @@ +Git signature format +==================== + +== Overview + +Git uses cryptographic signatures in various places, currently +objects (tags, commits, mergetags) and transactions (pushes). +In every case, the command which is about to create an object or +transaction determines a payload from that, calls gpg to obtain +a detached signature for the payload and embeds the signature +into the object or transaction. + +Signatures always begin with `-----BEGIN PGP SIGNATURE-----` +and end with `-----END PGP SIGNATURE-----`. + +== Tag signatures + +- created by: `git tag -s` +- payload: annotated tag object +- embedding: append the signature to the tag object +- example: tag `stag` with tag message `tagmess` + +---- +object 8cbad082a020b7d4ef729b14e1a654c4f60791c6 +type commit +tag stag +tagger Michael J Gruber <git@drmicha.warpmail.net> 1351067460 +0200 + +tagmess +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1.4.12 (GNU/Linux) + +iQIcBAABCgAGBQJQh6dPAAoJELR76rQkz552ZBEP/3vkpftZnhsUkGhqXXptnRhz +5A3n+BqFTsh4d4C15lcRcevwTyyQF61vrFKFRE7Cl5XVqVHowW0al+Dx7j5p35Mz +PqBZUbEkBFc9xY8WasQYbJl5yDboc8Ora71SEJ1k59duETXmZ67ISpEe6HF3d2xK +3BGfqaBMwU+Aql0pDMtysoOgEgs7d/Vin9gIXJcqAvw71bpNyZvFUln3do2eLC/v +VW0bVvAN3B66fLx3li8hEZ4wfrg0Uui5zSN95+uc2DUGW03BNR/sKhYXstHAoqef +4WIAD70e+9vArh8WqPTIUWl0w+1ixgVvGckHXHW10MdwkoVtwo4tawRxngLBKuI9 +pUu7dc/TIVl15z/y1EmQ25rB4WV9M9W+uRauUi/T3c0hfSuZkB6B1tCu3QStPbWz +AK3O6Neoni2NgMDLmrWzgDZA3Z/+h9RBV/kNda0RpbWZYJOJILBR+Q8+BZOwDZX/ +hu/tITC7IHVJgMXYGlEFybEn/clbtLsZr8zLlSZyropl0mvUBLeBCrjYBQuDN86g +yew/Tzs9T5MEFagUkbRERz5rP5OIE9XpXcHMsZve7cCL3YQy0LOkZk3RZKUsbv8g +MVU1px5/ImBkr0MU0XZxstsAV0YPiON3+qMOnrdGuFx11YQi6cmIA2eww2KPqzHY +YKirAGNintaD8yXAlwLd +=wF8p +-----END PGP SIGNATURE----- +---- + +== Commit signature + +- created by: `git commit -s` +- payload: commit object +- embedding: header entry `gpgsig` + (content is preceded by a space) +- example: commit with commit message `sigtest` + +---- +tree 14461762125c079e55a9684ae3a96e27de5b3f2f +parent da19995926ec89e48297a3163b0f5190af3a8650 +author Michael J Gruber <git@drmicha.warpmail.net> 1325088101 +0100 +committer Michael J Gruber <git@drmicha.warpmail.net> 1325088101 +0100 +gpgsig -----BEGIN PGP SIGNATURE----- + Version: GnuPG v1.4.11 (GNU/Linux) + + iQIcBAABCgAGBQJO+z1lAAoJELR76rQkz552xOoQAJgV6sstR8cge760X7awb00V + svN+pcc1TtJZecYWakCIe6dGPAK2Yk1AwExV0tbAQskPxYIqwnuysXHvVlmyJh5P + 1N033YSRc8j59YNQNaLIAh6+c59cKcZdWQyrA1HFVWGqoafCD2+nMglb/JbN9jqQ + 5gsxfFGoE0blT+BnMrchzPL4kjMJQBszV5ccATu3iIgSv23p5rA4tm3/P44enIsH + U9nYODlKmzsAulThQoSd4Qk0MNIg86MjIXanPkj4S+TLLgDa6Zf8W3m28IiRwPF1 + WemWpQ9VwSSHKuGVyHGG2OErtDDftILcYtjW5c/UnLw38hWPwc+KxVmAdEBY3vgk + OACDEDLqAWgc4rLdWgkoxieIi0aKN+iN4kogbEtSl4VzgvX0iGLZP8cyJnGxHria + Qz2UcesNqVPPqOxsIJKpr3CByrh2WDzH8W3tvGuy5q8EsTx5uF1HGoYb3PIx76QG + 3ClhL5Wtjk3/iQnycWo60eKMJccLbv+uoXzUP3LA0prt0K3a+52pWVppt8RW1L6u + kALJjsc44gr04v/fo5x6zkgFFt+8e/YWDZO+vwCJDmCyqggEvA5dj6i0y2B+hZjL + RVG0RATLroPgMa6oHSEVEbP+Ui4JZ3k3fRLIOupb0qjHtv/cvB7kcXevpdQUFGs0 + 6kmaMJBcWutA6HrosuP/ + =9PhX + -----END PGP SIGNATURE----- + +sigtest +---- + +== Mergetag signature + +- created by: `git merge` on signed tag +- payload/embedding: the whole signed tag object is embedded into + the (merge) commit object of header entry `mergetag` +- example: merge of the signed tag `stag` as above + +---- +tree ceb2177fea91ec9369e012dbe794419ee0731ce7 +parent 9c20ba82367dab0fe4789e2be400a7fb0c447c34 +parent 8cbad082a020b7d4ef729b14e1a654c4f60791c6 +author Michael J Gruber <git@drmicha.warpmail.net> 1412951117 +0200 +committer Michael J Gruber <git@drmicha.warpmail.net> 1412951117 +0200 +mergetag object 8cbad082a020b7d4ef729b14e1a654c4f60791c6 + type commit + tag stag + tagger Michael J Gruber <git@drmicha.warpmail.net> 1351067460 +0200 + + tagmess + -----BEGIN PGP SIGNATURE----- + Version: GnuPG v1.4.12 (GNU/Linux) + + iQIcBAABCgAGBQJQh6dPAAoJELR76rQkz552ZBEP/3vkpftZnhsUkGhqXXptnRhz + 5A3n+BqFTsh4d4C15lcRcevwTyyQF61vrFKFRE7Cl5XVqVHowW0al+Dx7j5p35Mz + PqBZUbEkBFc9xY8WasQYbJl5yDboc8Ora71SEJ1k59duETXmZ67ISpEe6HF3d2xK + 3BGfqaBMwU+Aql0pDMtysoOgEgs7d/Vin9gIXJcqAvw71bpNyZvFUln3do2eLC/v + VW0bVvAN3B66fLx3li8hEZ4wfrg0Uui5zSN95+uc2DUGW03BNR/sKhYXstHAoqef + 4WIAD70e+9vArh8WqPTIUWl0w+1ixgVvGckHXHW10MdwkoVtwo4tawRxngLBKuI9 + pUu7dc/TIVl15z/y1EmQ25rB4WV9M9W+uRauUi/T3c0hfSuZkB6B1tCu3QStPbWz + AK3O6Neoni2NgMDLmrWzgDZA3Z/+h9RBV/kNda0RpbWZYJOJILBR+Q8+BZOwDZX/ + hu/tITC7IHVJgMXYGlEFybEn/clbtLsZr8zLlSZyropl0mvUBLeBCrjYBQuDN86g + yew/Tzs9T5MEFagUkbRERz5rP5OIE9XpXcHMsZve7cCL3YQy0LOkZk3RZKUsbv8g + MVU1px5/ImBkr0MU0XZxstsAV0YPiON3+qMOnrdGuFx11YQi6cmIA2eww2KPqzHY + YKirAGNintaD8yXAlwLd + =wF8p + -----END PGP SIGNATURE----- + +Merge tag 'stag' into HEAD + +tagmess + +Conflicts: + ... +---- -- 2.1.2.756.gfa53a0a ^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber @ 2014-10-22 16:57 ` Jakub Narębski 2014-10-22 19:02 ` Junio C Hamano 1 sibling, 0 replies; 9+ messages in thread From: Jakub Narębski @ 2014-10-22 16:57 UTC (permalink / raw) To: Michael J Gruber, git W dniu 2014-10-22 17:16, Michael J Gruber napisał: > +== Commit signature > + > +- created by: `git commit -s` > +- payload: commit object > +- embedding: header entry `gpgsig` > + (content is preceded by a space) > +- example: commit with commit message `sigtest` Actually it is not "content is preceded by space", but it is multi-line header which uses RFC-2822 like wrapping (see "Long Header Fields" there) - leading space means wrapped in email, separate line here. Nice work. -- Jakub Narębski ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber 2014-10-22 16:57 ` Jakub Narębski @ 2014-10-22 19:02 ` Junio C Hamano 2014-10-24 15:36 ` Michael J Gruber 2014-10-25 8:30 ` Jakub Narębski 1 sibling, 2 replies; 9+ messages in thread From: Junio C Hamano @ 2014-10-22 19:02 UTC (permalink / raw) To: Michael J Gruber; +Cc: git Michael J Gruber <git@drmicha.warpmail.net> writes: > Various formats for storing signatures have accumulated by now. > Document them to keep track (and maybe avoid yet another one). I haven't looked at the description closely, but it is a good thing to describe signature in a tag and in a commit in detail, which we failed to do so far. The principle is essentially the same between the signature on a tag and on a commit: a detached PGP signature over the remainder of the object data is created, and then the signature is inserted into an appropriate place in the resulting object. That "appropriate place" is influenced by the type and nature of the object. A mergetag is not fundamentally a "signature" in the above sense, though. It is just a dump of the object content in a regular object header field (hence indented by one SP), and its contents having PGP SIGNATURE is merely a natural consequence of the object recorded being a signed tag. So the description of it in the same place as description for signed tags and signed commits feels a little bit out of place, but I do not think of a better place to describe it. Thanks. > Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> > --- > Documentation/Makefile | 1 + > Documentation/technical/signature-format.txt | 126 +++++++++++++++++++++++++++ > 2 files changed, 127 insertions(+) > create mode 100644 Documentation/technical/signature-format.txt > > diff --git a/Documentation/Makefile b/Documentation/Makefile > index cea0e7a..2638c0c 100644 > --- a/Documentation/Makefile > +++ b/Documentation/Makefile > @@ -74,6 +74,7 @@ TECH_DOCS += technical/protocol-common > TECH_DOCS += technical/racy-git > TECH_DOCS += technical/send-pack-pipeline > TECH_DOCS += technical/shallow > +TECH_DOCS += technical/signature-format > TECH_DOCS += technical/trivial-merge > SP_ARTICLES += $(TECH_DOCS) > SP_ARTICLES += technical/api-index > diff --git a/Documentation/technical/signature-format.txt > b/Documentation/technical/signature-format.txt > new file mode 100644 > index 0000000..80f0a47 > --- /dev/null > +++ b/Documentation/technical/signature-format.txt > @@ -0,0 +1,126 @@ > +Git signature format > +==================== > + > +== Overview > + > +Git uses cryptographic signatures in various places, currently > +objects (tags, commits, mergetags) and transactions (pushes). > +In every case, the command which is about to create an object or > +transaction determines a payload from that, calls gpg to obtain > +a detached signature for the payload and embeds the signature > +into the object or transaction. > + > +Signatures always begin with `-----BEGIN PGP SIGNATURE-----` > +and end with `-----END PGP SIGNATURE-----`. > + > +== Tag signatures > + > +- created by: `git tag -s` > +- payload: annotated tag object > +- embedding: append the signature to the tag object > +- example: tag `stag` with tag message `tagmess` > + > +---- > +object 8cbad082a020b7d4ef729b14e1a654c4f60791c6 > +type commit > +tag stag > +tagger Michael J Gruber <git@drmicha.warpmail.net> 1351067460 +0200 > + > +tagmess > +-----BEGIN PGP SIGNATURE----- > +Version: GnuPG v1.4.12 (GNU/Linux) > + > +iQIcBAABCgAGBQJQh6dPAAoJELR76rQkz552ZBEP/3vkpftZnhsUkGhqXXptnRhz > +5A3n+BqFTsh4d4C15lcRcevwTyyQF61vrFKFRE7Cl5XVqVHowW0al+Dx7j5p35Mz > +PqBZUbEkBFc9xY8WasQYbJl5yDboc8Ora71SEJ1k59duETXmZ67ISpEe6HF3d2xK > +3BGfqaBMwU+Aql0pDMtysoOgEgs7d/Vin9gIXJcqAvw71bpNyZvFUln3do2eLC/v > +VW0bVvAN3B66fLx3li8hEZ4wfrg0Uui5zSN95+uc2DUGW03BNR/sKhYXstHAoqef > +4WIAD70e+9vArh8WqPTIUWl0w+1ixgVvGckHXHW10MdwkoVtwo4tawRxngLBKuI9 > +pUu7dc/TIVl15z/y1EmQ25rB4WV9M9W+uRauUi/T3c0hfSuZkB6B1tCu3QStPbWz > +AK3O6Neoni2NgMDLmrWzgDZA3Z/+h9RBV/kNda0RpbWZYJOJILBR+Q8+BZOwDZX/ > +hu/tITC7IHVJgMXYGlEFybEn/clbtLsZr8zLlSZyropl0mvUBLeBCrjYBQuDN86g > +yew/Tzs9T5MEFagUkbRERz5rP5OIE9XpXcHMsZve7cCL3YQy0LOkZk3RZKUsbv8g > +MVU1px5/ImBkr0MU0XZxstsAV0YPiON3+qMOnrdGuFx11YQi6cmIA2eww2KPqzHY > +YKirAGNintaD8yXAlwLd > +=wF8p > +-----END PGP SIGNATURE----- > +---- > + > +== Commit signature > + > +- created by: `git commit -s` > +- payload: commit object > +- embedding: header entry `gpgsig` > + (content is preceded by a space) > +- example: commit with commit message `sigtest` > + > +---- > +tree 14461762125c079e55a9684ae3a96e27de5b3f2f > +parent da19995926ec89e48297a3163b0f5190af3a8650 > +author Michael J Gruber <git@drmicha.warpmail.net> 1325088101 +0100 > +committer Michael J Gruber <git@drmicha.warpmail.net> 1325088101 +0100 > +gpgsig -----BEGIN PGP SIGNATURE----- > + Version: GnuPG v1.4.11 (GNU/Linux) > + > + iQIcBAABCgAGBQJO+z1lAAoJELR76rQkz552xOoQAJgV6sstR8cge760X7awb00V > + svN+pcc1TtJZecYWakCIe6dGPAK2Yk1AwExV0tbAQskPxYIqwnuysXHvVlmyJh5P > + 1N033YSRc8j59YNQNaLIAh6+c59cKcZdWQyrA1HFVWGqoafCD2+nMglb/JbN9jqQ > + 5gsxfFGoE0blT+BnMrchzPL4kjMJQBszV5ccATu3iIgSv23p5rA4tm3/P44enIsH > + U9nYODlKmzsAulThQoSd4Qk0MNIg86MjIXanPkj4S+TLLgDa6Zf8W3m28IiRwPF1 > + WemWpQ9VwSSHKuGVyHGG2OErtDDftILcYtjW5c/UnLw38hWPwc+KxVmAdEBY3vgk > + OACDEDLqAWgc4rLdWgkoxieIi0aKN+iN4kogbEtSl4VzgvX0iGLZP8cyJnGxHria > + Qz2UcesNqVPPqOxsIJKpr3CByrh2WDzH8W3tvGuy5q8EsTx5uF1HGoYb3PIx76QG > + 3ClhL5Wtjk3/iQnycWo60eKMJccLbv+uoXzUP3LA0prt0K3a+52pWVppt8RW1L6u > + kALJjsc44gr04v/fo5x6zkgFFt+8e/YWDZO+vwCJDmCyqggEvA5dj6i0y2B+hZjL > + RVG0RATLroPgMa6oHSEVEbP+Ui4JZ3k3fRLIOupb0qjHtv/cvB7kcXevpdQUFGs0 > + 6kmaMJBcWutA6HrosuP/ > + =9PhX > + -----END PGP SIGNATURE----- > + > +sigtest > +---- > + > +== Mergetag signature > + > +- created by: `git merge` on signed tag > +- payload/embedding: the whole signed tag object is embedded into > + the (merge) commit object of header entry `mergetag` > +- example: merge of the signed tag `stag` as above > + > +---- > +tree ceb2177fea91ec9369e012dbe794419ee0731ce7 > +parent 9c20ba82367dab0fe4789e2be400a7fb0c447c34 > +parent 8cbad082a020b7d4ef729b14e1a654c4f60791c6 > +author Michael J Gruber <git@drmicha.warpmail.net> 1412951117 +0200 > +committer Michael J Gruber <git@drmicha.warpmail.net> 1412951117 +0200 > +mergetag object 8cbad082a020b7d4ef729b14e1a654c4f60791c6 > + type commit > + tag stag > + tagger Michael J Gruber <git@drmicha.warpmail.net> 1351067460 +0200 > + > + tagmess > + -----BEGIN PGP SIGNATURE----- > + Version: GnuPG v1.4.12 (GNU/Linux) > + > + iQIcBAABCgAGBQJQh6dPAAoJELR76rQkz552ZBEP/3vkpftZnhsUkGhqXXptnRhz > + 5A3n+BqFTsh4d4C15lcRcevwTyyQF61vrFKFRE7Cl5XVqVHowW0al+Dx7j5p35Mz > + PqBZUbEkBFc9xY8WasQYbJl5yDboc8Ora71SEJ1k59duETXmZ67ISpEe6HF3d2xK > + 3BGfqaBMwU+Aql0pDMtysoOgEgs7d/Vin9gIXJcqAvw71bpNyZvFUln3do2eLC/v > + VW0bVvAN3B66fLx3li8hEZ4wfrg0Uui5zSN95+uc2DUGW03BNR/sKhYXstHAoqef > + 4WIAD70e+9vArh8WqPTIUWl0w+1ixgVvGckHXHW10MdwkoVtwo4tawRxngLBKuI9 > + pUu7dc/TIVl15z/y1EmQ25rB4WV9M9W+uRauUi/T3c0hfSuZkB6B1tCu3QStPbWz > + AK3O6Neoni2NgMDLmrWzgDZA3Z/+h9RBV/kNda0RpbWZYJOJILBR+Q8+BZOwDZX/ > + hu/tITC7IHVJgMXYGlEFybEn/clbtLsZr8zLlSZyropl0mvUBLeBCrjYBQuDN86g > + yew/Tzs9T5MEFagUkbRERz5rP5OIE9XpXcHMsZve7cCL3YQy0LOkZk3RZKUsbv8g > + MVU1px5/ImBkr0MU0XZxstsAV0YPiON3+qMOnrdGuFx11YQi6cmIA2eww2KPqzHY > + YKirAGNintaD8yXAlwLd > + =wF8p > + -----END PGP SIGNATURE----- > + > +Merge tag 'stag' into HEAD > + > +tagmess > + > +Conflicts: > + ... > +---- ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-22 19:02 ` Junio C Hamano @ 2014-10-24 15:36 ` Michael J Gruber 2014-10-24 17:10 ` Junio C Hamano 2014-10-25 8:30 ` Jakub Narębski 1 sibling, 1 reply; 9+ messages in thread From: Michael J Gruber @ 2014-10-24 15:36 UTC (permalink / raw) To: Junio C Hamano, Jakub Narebski; +Cc: git Junio C Hamano schrieb am 22.10.2014 um 21:02: > Michael J Gruber <git@drmicha.warpmail.net> writes: > >> Various formats for storing signatures have accumulated by now. >> Document them to keep track (and maybe avoid yet another one). > > I haven't looked at the description closely, but it is a good thing > to describe signature in a tag and in a commit in detail, which we > failed to do so far. > > The principle is essentially the same between the signature on a tag > and on a commit: a detached PGP signature over the remainder of the > object data is created, and then the signature is inserted into an > appropriate place in the resulting object. That "appropriate place" > is influenced by the type and nature of the object. Yes, the detached signature can't easily be appended to a commit object the way it follows a tag object. Conversely, signed tag could easily look like signed commits do (sig in header), but that would require a migration procedure. > A mergetag is not fundamentally a "signature" in the above sense, > though. It is just a dump of the object content in a regular object > header field (hence indented by one SP), and its contents having PGP > SIGNATURE is merely a natural consequence of the object recorded > being a signed tag. So the description of it in the same place as > description for signed tags and signed commits feels a little bit > out of place, but I do not think of a better place to describe it. I guess referencing the tag object (like other objects do) rather than embedding it would have had its merits, but that is beating up a dead horse. On the other hand, we could migrate to "mergetag sha1" rather than "mergetag object foo" which is easily distinguished, but only embedded objects are "safe" against non-aware gits. > Thanks. Thanks, Jakub and Junio. I will correct the wording for the multiline header and put the mergetag last to make it clearer that it's related but different. Michael ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-24 15:36 ` Michael J Gruber @ 2014-10-24 17:10 ` Junio C Hamano 0 siblings, 0 replies; 9+ messages in thread From: Junio C Hamano @ 2014-10-24 17:10 UTC (permalink / raw) To: Michael J Gruber; +Cc: Jakub Narebski, git Michael J Gruber <git@drmicha.warpmail.net> writes: > Junio C Hamano schrieb am 22.10.2014 um 21:02: >> Michael J Gruber <git@drmicha.warpmail.net> writes: >> >>> Various formats for storing signatures have accumulated by now. >>> Document them to keep track (and maybe avoid yet another one). >> >> I haven't looked at the description closely, but it is a good thing >> to describe signature in a tag and in a commit in detail, which we >> failed to do so far. >> >> The principle is essentially the same between the signature on a tag >> and on a commit: a detached PGP signature over the remainder of the >> object data is created, and then the signature is inserted into an >> appropriate place in the resulting object. That "appropriate place" >> is influenced by the type and nature of the object. > > Yes, the detached signature can't easily be appended to a commit object > the way it follows a tag object. Conversely, signed tag could easily > look like signed commits do (sig in header), but that would require a > migration procedure. I do not see much point in doing such "migration", though. Whom is it supposed to help? >> A mergetag is not fundamentally a "signature" in the above sense, >> though. It is just a dump of the object content in a regular object >> header field (hence indented by one SP), and its contents having PGP >> SIGNATURE is merely a natural consequence of the object recorded >> being a signed tag. So the description of it in the same place as >> description for signed tags and signed commits feels a little bit >> out of place, but I do not think of a better place to describe it. > > I guess referencing the tag object (like other objects do) rather than > embedding it would have had its merits, but that is beating up a dead > horse. Such a format would have defeated a major point of mergetag. The header embeds the data, not a reference to an external object, so that the resulting merge commit can be validated without having an extra tag. The resulting repository does not have to keep a tag reference that nobody else is interested in, which is an added bonus. I however agree that if there were no downside having to reference and maintain an extra tag, having the data there (i.e. the real "mergetag" format) and a reference there (i.e. your alternative) would have the same level of security and assurance. That tells us that whatever is on "mergetag" is "not fundamentally a signature", as I said already, doesn't it, though? The description of "mergetag" in this document should not have to change, even when the mechanism used to sign underlying "tag" objects were to change in the future. For that, you can just say that it is just a bit-for-bit copy of the tag object that was pulled into the history with the merge. The way how bits from the tag object are recorded there needs to be described. What the bits mean (e.g. it has a detached GPG signature over what appeneded in what way) does not need to be (and I think should not be) repeated in the description of "mergetag". ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-22 19:02 ` Junio C Hamano 2014-10-24 15:36 ` Michael J Gruber @ 2014-10-25 8:30 ` Jakub Narębski 2014-10-30 10:19 ` Michael J Gruber 1 sibling, 1 reply; 9+ messages in thread From: Jakub Narębski @ 2014-10-25 8:30 UTC (permalink / raw) To: Junio C Hamano, Michael J Gruber; +Cc: git W dniu 2014-10-22 21:02, Junio C Hamano pisze: > A mergetag is not fundamentally a "signature" in the above sense, > though. It is just a dump of the object content in a regular object > header field (hence indented by one SP), and its contents having PGP > SIGNATURE is merely a natural consequence of the object recorded > being a signed tag. So the description of it in the same place as > description for signed tags and signed commits feels a little bit > out of place, but I do not think of a better place to describe it. Does this mean that you can merge annotated (but not signed) tag, and have it (as description of merged branch) in 'mergetag' header? -- Jakub Narębski ^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/2] Documentation/technical: signature formats 2014-10-25 8:30 ` Jakub Narębski @ 2014-10-30 10:19 ` Michael J Gruber 0 siblings, 0 replies; 9+ messages in thread From: Michael J Gruber @ 2014-10-30 10:19 UTC (permalink / raw) To: Jakub Narębski, Junio C Hamano; +Cc: git Jakub Narębski schrieb am 25.10.2014 um 10:30: > W dniu 2014-10-22 21:02, Junio C Hamano pisze: > >> A mergetag is not fundamentally a "signature" in the above sense, >> though. It is just a dump of the object content in a regular object >> header field (hence indented by one SP), and its contents having PGP >> SIGNATURE is merely a natural consequence of the object recorded >> being a signed tag. So the description of it in the same place as >> description for signed tags and signed commits feels a little bit >> out of place, but I do not think of a better place to describe it. > > Does this mean that you can merge annotated (but not signed) tag, > and have it (as description of merged branch) in 'mergetag' header? We don't do that (so far). In principle we could do that, of course. (But I really wish mergetag would point to the tag object rather than embed it.) But the point of the merge tag is to "bake into the commit object" some verifiable information about the source of the merge, or rather about some of its parents. Just adding some non-verifiable, "come-and-go" information seems to be more suited for notes. Michael ^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH 2/2] Documentation/technical: document push certificate format 2014-10-22 15:16 [PATCH 0/2] document signature formats Michael J Gruber 2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber @ 2014-10-22 15:16 ` Michael J Gruber 1 sibling, 0 replies; 9+ messages in thread From: Michael J Gruber @ 2014-10-22 15:16 UTC (permalink / raw) To: git Signed-off-by: Michael J Gruber <git@drmicha.warpmail.net> --- Documentation/technical/signature-format.txt | 35 ++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) diff --git a/Documentation/technical/signature-format.txt b/Documentation/technical/signature-format.txt index 80f0a47..49c2c82 100644 --- a/Documentation/technical/signature-format.txt +++ b/Documentation/technical/signature-format.txt @@ -124,3 +124,38 @@ tagmess Conflicts: ... ---- + +== Push certificate + +- created by: `git push --signed` +- payload: a push certificate header followed by the push transcript + (see pack-protocol.txt) +- embedding: append the signature to the push transcript +- example: push of commit `21723` updating `master` on `localhost` + from `45cfe` + +---- +certificate version 0.1 +pusher Michael J Gruber <drmicha@warpmail.net> 1413979846 +0200 +pushee localhost:/tmp/t/a +nonce 1413979846-48813c0bc9d3b598d71d + +45cfec8735b7842a32dcc092a14850aa6220ef33 217230e5793407fc7c099117011ed13143fece63 refs/heads/master +-----BEGIN PGP SIGNATURE----- +Version: GnuPG v1 + +iQIcBAABCgAGBQJUR57GAAoJELR76rQkz552EWMP/3yHaFYuG3T/FcshgXQubsml +t4TvkegjQFtVK31oedqaAQGJYusXX2/yUFviXpRq611Aj7rooBnpZYZKT5lUm/ol +m9KjDvFpOiY7rA/y6BBetSX6s6uhmO4WcgJ4hSsMZ4z+001y2zawxWm0cedurIcO +hpKbAmQ/EiMmQiA4D9vKmLJUXpzF63NzMElZfWzHLa0IU1ZN6EvH1l+N7ulBNsuv +lTh3UxjabJr4vpu6kwMquCGqRB60+rdG7itiHwRQynnmDhvXoQxtU9gtLymXKJIS +SGQ5v3B5hsGA2LkCCkvNj+QRLH9LF8iAZqezqGA5U/Cg7xckOPlMwFllTv8goDBW +IB7Mk5lpQqaUCZf33uIppiEtHipLpGI90NLCm+JvzrNnnseSS6jARVRMx6cWp+dB +9QTCq80mRI/zzcvDyPhNvj0tP3mUTFmR4+KRh+4zRq9iOGp5KpJrpFjndCQELwAW +402hXEEjB4Kq7KSU4jEoaYGrJR9KJmPmgWHvz2GaJZ5eCJIXuoLGZo3TtxXRHB9p +EqWp3iZOZotxZmUVHgohFhqxZgcAefdfzZUqQ8jY3hHvu5Zwd2muToc8Nh/vIHoB +us0NHUiI8TOccAHd8AIrqgoXj2gChr3cQxWNcfBfx+ALT8sEtNrVkkrovmRiMEa4 +MxEdQTwhooEE8PWD5Yj5 +=6MAR +-----END PGP SIGNATURE----- +---- -- 2.1.2.756.gfa53a0a ^ permalink raw reply related [flat|nested] 9+ messages in thread
end of thread, other threads:[~2014-10-30 10:19 UTC | newest] Thread overview: 9+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-10-22 15:16 [PATCH 0/2] document signature formats Michael J Gruber 2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber 2014-10-22 16:57 ` Jakub Narębski 2014-10-22 19:02 ` Junio C Hamano 2014-10-24 15:36 ` Michael J Gruber 2014-10-24 17:10 ` Junio C Hamano 2014-10-25 8:30 ` Jakub Narębski 2014-10-30 10:19 ` Michael J Gruber 2014-10-22 15:16 ` [PATCH 2/2] Documentation/technical: document push certificate format Michael J Gruber
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