How to Verify Git GPG Signed Downloads?

How to Verify Git GPG Signed Downloads?

[Brooke Kuhlmann]

Hello, I'm trying to figure out how to obtain the public key used to encrypt the Git file downloads. I put together a gist that explains the problem and question in detail here:

https://gist.github.com/bkuhlmann/684b74d25d83d52df8d0caeb6219aa15

If anyone has any advice on how to make this possible, it would be greatly appreciated.

Thanks,
Brooke

RE: How to Verify Git GPG Signed Downloads?

[Jason Pyeron]

> From: Brooke Kuhlmann
> Sent: Sunday, January 24, 2021 11:49 AM
> 
> Hello, I'm trying to figure out how to obtain the public key used to 
> encrypt 

Do you mean sign?

> the Git file
> downloads. I put together a gist that explains the problem and question in detail here:
> 
> https://gist.github.com/bkuhlmann/684b74d25d83d52df8d0caeb6219aa15

Please don’t post links to questions, pasting your content inline here:

> Problem
> When attempting to download a Git version, it would be nice to verify the signature of the download by running the following:
>
> curl --remote-name https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.30.0.tar.gz
> curl --remote-name https://mirrors.edge.kernel.org/pub/software/scm/git/git-2.30.0.tar.sign
> gpg --verify git-2.30.0.tar.sign git-2.30.0.tar.gz
> Only problem is that the last line of the above throws the following error:
>
> gpg: Signature made Sun Dec 27 23:12:30 2020 MST
> gpg:                using RSA key E1F036B1FEE7221FC778ECEFB0B5E88696AFE6CB
> gpg: Can't check signature: No public key
> I tried using the following solutions to no avail:

$ gpg --recv-keys 96AFE6CB
gpg: requesting key 96AFE6CB from hkp server keys.gnupg.net
gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 59 new signatures
gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 2 new subkeys
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:            new subkeys: 2
gpg:         new signatures: 59

$ gpg --verify -v git-2.30.0.tar.sign git-2.30.0.tar.gz
gpg: Signature made Mon Dec 28 01:12:30 2020 EST using RSA key ID 96AFE6CB
gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
gpg: using subkey 96AFE6CB instead of primary key 713660A7
gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
gpg: using PGP trust model
gpg: BAD signature from "Junio C Hamano <gitster@pobox.com>"
gpg: binary signature, digest algorithm SHA256

$ gpg --list-keys -v 96AFE6CB
gpg: using PGP trust model
gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
pub   4096R/713660A7 2011-10-01
uid                  Junio C Hamano <gitster@pobox.com>
uid                  Junio C Hamano <junio@pobox.com>
uid                  Junio C Hamano <jch@google.com>
sub   4096R/96AFE6CB 2011-10-03 [expired: 2020-07-26]
sub   4096R/833262C4 2011-10-01
sub   4096R/B3F7CAC9 2014-09-20 [expired: 2020-07-26]

It is possible that Junio forgot to push his refreshed public key.

>
> gpg --locate-keys torvalds@kernel.org gregkh@kernel.org committer@example.com discord@example.net gitster@pobox.com
> gpg --import <file> # <= Need a file to import but where does one obtain the public key?
> I also tried importing only the public keys from the Git repository via the following files without any luck either:
>
> t/lib-gpg/keyring.gpg
> contrib/credential/netrc/test.git-config-gpg
> contrib/credential/netrc/test.netrc.gpg
> contrib/credential/netrc/test.command-option-gpg
> Question
> How does one figure out how to obtain the public keys for which the Git downloads were signed?
> 
> If anyone has any advice on how to make this possible, it would be greatly appreciated.
> 
> Thanks,
> Brooke
> 

Re: How to Verify Git GPG Signed Downloads?

[brian m. carlson]

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On 2021-01-24 at 17:57:13, Jason Pyeron wrote:
> $ gpg --recv-keys 96AFE6CB
> gpg: requesting key 96AFE6CB from hkp server keys.gnupg.net
> gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 59 new signatures
> gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 2 new subkeys
> gpg: no ultimately trusted keys found
> gpg: Total number processed: 1
> gpg:            new subkeys: 2
> gpg:         new signatures: 59
> 
> $ gpg --verify -v git-2.30.0.tar.sign git-2.30.0.tar.gz
> gpg: Signature made Mon Dec 28 01:12:30 2020 EST using RSA key ID 96AFE6CB
> gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> gpg: using subkey 96AFE6CB instead of primary key 713660A7
> gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> gpg: using PGP trust model
> gpg: BAD signature from "Junio C Hamano <gitster@pobox.com>"
> gpg: binary signature, digest algorithm SHA256

The signature is bad because it's over the uncompressed .tar, not the
.tar.gz.  There is also a .tar.xz and the signature is the same.  You
therefore need to uncompress it first with gunzip.

> $ gpg --list-keys -v 96AFE6CB
> gpg: using PGP trust model
> gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> pub   4096R/713660A7 2011-10-01
> uid                  Junio C Hamano <gitster@pobox.com>
> uid                  Junio C Hamano <junio@pobox.com>
> uid                  Junio C Hamano <jch@google.com>
> sub   4096R/96AFE6CB 2011-10-03 [expired: 2020-07-26]
> sub   4096R/833262C4 2011-10-01
> sub   4096R/B3F7CAC9 2014-09-20 [expired: 2020-07-26]
> 
> It is possible that Junio forgot to push his refreshed public key.

Yes, I think that's the case.
-- 
brian m. carlson (he/him or they/them)
Houston, Texas, US

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 263 bytes --]

RE: How to Verify Git GPG Signed Downloads?

[Jason Pyeron]

> From: brian m. carlson
> Sent: Sunday, January 24, 2021 4:34 PM
> 
> On 2021-01-24 at 17:57:13, Jason Pyeron wrote:
> > $ gpg --recv-keys 96AFE6CB
> > gpg: requesting key 96AFE6CB from hkp server keys.gnupg.net
> > gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 59 new signatures
> > gpg: key 713660A7: "Junio C Hamano <gitster@pobox.com>" 2 new subkeys
> > gpg: no ultimately trusted keys found
> > gpg: Total number processed: 1
> > gpg:            new subkeys: 2
> > gpg:         new signatures: 59
> >
> > $ gpg --verify -v git-2.30.0.tar.sign git-2.30.0.tar.gz
> > gpg: Signature made Mon Dec 28 01:12:30 2020 EST using RSA key ID 96AFE6CB
> > gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> > gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> > gpg: using subkey 96AFE6CB instead of primary key 713660A7
> > gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> > gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> > gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> > gpg: using PGP trust model
> > gpg: BAD signature from "Junio C Hamano <gitster@pobox.com>"
> > gpg: binary signature, digest algorithm SHA256
> 
> The signature is bad because it's over the uncompressed .tar, not the
> .tar.gz.  There is also a .tar.xz and the signature is the same.  You
> therefore need to uncompress it first with gunzip.

Silly me, but maybe there should be a README in that directory, along with the signatures.asc. If not, then it should easily be found on the git-scm site.

$ gpg --verify  git-2.30.0.tar.sign git-2.30.0.tar
gpg: Signature made Mon Dec 28 01:12:30 2020 EST using RSA key ID 96AFE6CB
gpg: Good signature from "Junio C Hamano <gitster@pobox.com>"
gpg:                 aka "Junio C Hamano <junio@pobox.com>"
gpg:                 aka "Junio C Hamano <jch@google.com>"
gpg: Note: This key has expired!
Primary key fingerprint: 96E0 7AF2 5771 9559 80DA  D100 20D0 4E5A 7136 60A7
     Subkey fingerprint: E1F0 36B1 FEE7 221F C778  ECEF B0B5 E886 96AF E6CB

> 
> > $ gpg --list-keys -v 96AFE6CB
> > gpg: using PGP trust model
> > gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
> > gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
> > pub   4096R/713660A7 2011-10-01
> > uid                  Junio C Hamano <gitster@pobox.com>
> > uid                  Junio C Hamano <junio@pobox.com>
> > uid                  Junio C Hamano <jch@google.com>
> > sub   4096R/96AFE6CB 2011-10-03 [expired: 2020-07-26]
> > sub   4096R/833262C4 2011-10-01
> > sub   4096R/B3F7CAC9 2014-09-20 [expired: 2020-07-26]
> >
> > It is possible that Junio forgot to push his refreshed public key.
> 
> Yes, I think that's the case.

Re: How to Verify Git GPG Signed Downloads?

[Junio C Hamano]

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

>> $ gpg --list-keys -v 96AFE6CB
>> gpg: using PGP trust model
>> gpg: NOTE: signature key 96AFE6CB expired Sun Jul 26 13:41:24 2020 EDT
>> gpg: NOTE: signature key B3F7CAC9 expired Sun Jul 26 13:41:42 2020 EDT
>> pub   4096R/713660A7 2011-10-01
>> uid                  Junio C Hamano <gitster@pobox.com>
>> uid                  Junio C Hamano <junio@pobox.com>
>> uid                  Junio C Hamano <jch@google.com>
>> sub   4096R/96AFE6CB 2011-10-03 [expired: 2020-07-26]
>> sub   4096R/833262C4 2011-10-01
>> sub   4096R/B3F7CAC9 2014-09-20 [expired: 2020-07-26]
>> 
>> It is possible that Junio forgot to push his refreshed public key.
>
> Yes, I think that's the case.

Hmph, I was fairly sure I pushed it out when I refreshed the expiry
date sometime early last year, but apparently it did not go through.

I just tried recv-keys from keys.gnupg.net into a throw-away
GNUPGHOME and got the output at the end, so it should be OK now.
Sorry about that.


$ gpg --list-keys -v 96AFE6CB
gpg: using pgp trust model
pub   rsa4096 2011-10-01 [SC]
      96E07AF25771955980DAD10020D04E5A713660A7
uid           [ unknown] Junio C Hamano <gitster@pobox.com>
uid           [ unknown] Junio C Hamano <jch@google.com>
uid           [ unknown] Junio C Hamano <junio@pobox.com>
sub   rsa4096 2011-10-01 [E]
sub   rsa4096 2011-10-03 [S] [expires: 2028-01-11]
sub   rsa4096 2014-09-20 [S] [expires: 2028-01-11]