From mboxrd@z Thu Jan  1 00:00:00 1970
From: cgit at cryptocrack.de (Lukas Fleischer)
Date: Sat, 07 Mar 2015 18:49:32 +0100
Subject: [PATCH] Check SHA256 sum of git-$VER.tar.gz after downloading
In-Reply-To: <20150307170259.GI1369@serenity.lan>
References: <0146555fda82120aa6ff6a7e9761d00d53ced865.1425739601.git.john@keeping.me.uk>
 <20150307155926.6430.47439@typhoon> <20150307170259.GI1369@serenity.lan>
Message-ID: <20150307174932.8657.41364@typhoon>

On Sat, 07 Mar 2015 at 18:02:59, John Keeping wrote:
> [...]
> I'm not sure what benefit it has if it's optional.  Will anyone check?
> 
> Maybe we could do something like:
> 
>         if type sha256sum >/dev/null 2>&1
>         then
>                 sha256sum --check git.sha256sum $(GIT_FILE)
>         else
>                 echo >&2 'WARNING: sha256sum not found so we cannot verify'
>                 echo >&2 'WARNING: the integrity of the Git archive!'
>         fi
> 

That is exactly what I meant by suggesting to make it optional. Sorry
for being vague...

> > On a related note, can we download a signature and use `gpg --verify`
> > instead (should probably be optional as well, to avoid a dependency on
> > GnuPG)?
> 
> I thought about that, but we'd have to embed a key with CGit for it to
> work reliably and how do we choose what key to use (given that
> individual Git archives are not signed - the list of SHA256 checksums
> is)?
> 

Huh? This works fine for me:

    $ gpg --recv-keys 96AFE6CB 
    gpg: key 713660A7: public key "Junio C Hamano <gitster at pobox.com>" imported
    gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
    gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
    gpg: Total number processed: 1
    gpg:               imported: 1
    $ curl -OO https://www.kernel.org/pub/software/scm/git/git-2.3.2.tar.{xz,sign} 
      % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                     Dload  Upload   Total   Spent    Left  Speed
    100 3529k  100 3529k    0     0  1133k      0  0:00:03  0:00:03 --:--:-- 1133k
    100   543  100   543    0     0   3404      0 --:--:-- --:--:-- --:--:--  3404
    $ unxz git-2.3.2.tar.xz
    $ gpg --verify git-2.3.2.tar.sign 
    gpg: assuming signed data in 'git-2.3.2.tar'
    gpg: Signature made Sat 07 Mar 2015 12:10:41 AM CET using RSA key ID 96AFE6CB
    gpg: Good signature from "Junio C Hamano <gitster at pobox.com>" [unknown]
    gpg:                 aka "Junio C Hamano <jch at google.com>" [unknown]
    gpg:                 aka "Junio C Hamano <junio at pobox.com>" [unknown]
    gpg: WARNING: This key is not certified with a trusted signature!
    gpg:          There is no indication that the signature belongs to the owner.
    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