6

I like to put the contents of /etc inside git, so I can see what auto-updates change, and when something breaks, so I can go back and find out what I changed since it last worked.

At the moment I'm being told:

modified:   trusted.gpg
modified:   trusted.gpg~

git diff is no use as these are binary files. Of course I could check them in, but these files are central to package security, so doing that would make mockery of my attempts at being secure! So, how do I find out what has changed?

As root I've tried:

cd /etc/apt
gpg -k trusted.gpg

(also tried --list-keys, --list-public-keys). It says gpg: error reading key: public key not found.

I'm sure it must just be a matter of discovering the correct parameters to give to gpg?

10

$ apt-key list

From the docs on secure apt:

apt-key is a program that is used to manage a keyring of gpg keys for secure apt. The keyring is kept in the file /etc/apt/trusted.gpg (not to be confused with the related but not very interesting /etc/apt/trustdb.gpg). apt-key can be used to show the keys in the keyring, and to add or remove a key.

  • 3
    Wonderful, thank-you. Then to see the differences I did diff <(apt-key --keyring /etc/apt/trusted.gpg list) <(apt-key --keyring /etc/apt/trusted.gpg~ list) (NB. full paths are essential for the --keyring parameter) P.S. actually I used meld not diff, of course ;-) meld clearly showed me that Opera has added a second key on July 3rd 2013. – Darren Cook Jul 11 '13 at 1:34
2

I came across this question while I too was trying to figure out how to get information on a public key file using GnuPG. In addition to the commands Darren tried, I also tried --fingerprint but got the same gpg: error reading key: public key not found error message.

After discovering the answer, I thought I’d complement Andrew's answer with a more general way of printing information about any public key file:

$ gpg --with-fingerprint /etc/apt/trusted.gpg

pub  1024D/437D05B5 2004-09-12 Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com>
      Key fingerprint = 6302 39CC 130E 1A7F D81A  27B1 4097 6EAF 437D 05B5
sub  2048g/79164387 2004-09-12
pub  4096R/C0B21F32 2012-05-11 Ubuntu Archive Automatic Signing Key (2012) <ftpmaster@ubuntu.com>
      Key fingerprint = 790B C727 7767 219C 42C8  6F93 3B4F E6AC C0B2 1F32
pub  4096R/EFE21092 2012-05-11 Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>
      Key fingerprint = 8439 38DF 228D 22F7 B374  2BC0 D94A A3F0 EFE2 1092
pub  1024D/FBB75451 2004-12-30 Ubuntu CD Image Automatic Signing Key <cdimage@ubuntu.com>
      Key fingerprint = C598 6B4F 1257 FFA8 6632  CBA7 4618 1433 FBB7 5451

As can be seen, the above lists the same information as the output of apt-key list – though the formatting of apt-key is much more readable.

The gpg man page only states that the --with-fingerprint option should be the “Same as the command --fingerprint” but (with GnuPG 1.4.20), it also lists fingerprints when a filename is supplied instead of a key ID. As the above example shows, this option can also be used to print the fingerprints of a public ring containing multiple keys.

1

If you are using gpg -k --keyring <file> make sure that you specify the file path otherwise gpg will assume <file> is located in ~/.gnupg/ even if it exists in the current directory!

The following won't work as expected:

cd /etc/apt
gpg -k --no-default-keyring --keyring trusted.gpg

Instead:

cd /etc/apt
gpg -k --no-default-keyring --keyring ./trusted.gpg

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