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When given a file with an armored public GnuPG key, i.e. a file (pubkey.gpg) that was created with:

gpg -r 0xDEADBEEF --export --armored > pubkey.gpg

What is the best way to get information such as the finger print in that file, without importing it into my keyring?

The best way I found so far (and I am not happy with) is:

gpg --dry-run --import pubkey.gpg

Naturally, I grepped the gpg man page, but didn't find an obvious solution.

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4 Answers 4

Reset to default
8

I don't know that gpg has an option for this, but here's a more flexible workaround for extracting information from the key file:

mkdir temp-gnupg-dir
export GNUPGHOME=temp-gnupg-dir
gpg --import pubkey.gpg
gpg --list-keys
rm -r temp-gnupg-dir

Instead of the GNUPGHOME environment variable, you can pass --homedir=temp-gnupg-dir to every gpg invocation.

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2
  • This is not pretty, but it is useful to know what options are not available, and this is a solution. So I thank you for that.
    – Chen Levy
    Aug 8, 2010 at 13:27
  • 1
    While this will work, it's way more complicated than necessary. Below I posted how to do it without any of the importing or keychain switching.
    – jm3
    Nov 17, 2013 at 3:17
18

To print the fingerprint of an on-disk armored key without importing it, just use --with-fingerprint:

> gpg --with-fingerprint jm3.asc

pub  1024R/9112BC51 1996-02-05 john manoogian <jm3@*>
Key fingerprint = C9 DC 27 29 0E 1A DB 50  21 C8 64 08 15 29 41 86

uid                            john manoogian <jm3@foo...
uid                            john manoogian <jm3@bar...
uid                            john manoogian <jm3@baz...
uid                            john manoogian <jm3@qux...

Voilà!

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3
  • This will create a gnupg directory and a default keyring if one does not exist. The accepted answer does not have that side-effect.
    – Etan Reisner
    Aug 11, 2014 at 3:30
  • --with-fingerprint is optional.
    – x-yuri
    May 20, 2015 at 13:21
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    This no longer works. My gpg version is 2.2.5.
    – Dan Milon
    May 8, 2018 at 12:15
6

You can checkout Kazu Yamamoto's PGP packet visualizer which displays the packet format of OpenPGP (RFC 4880) and PGP version 2 (RFC 1991).

To fetch and compile:

git clone http://github.com/kazu-yamamoto/pgpdump
cd pgpdump
./configure --prefix=/usr/local/ && make && sudo make install

Using it is even simpler:

pgpdump pubkey.gpg

There is also a cgi-bin interface available on this site: http://www.pgpdump.net/cgi-bin/pgpdump

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2
  • 1
    This is awesome! And kudos to a fellow Haskeller Kazu :) BTW, pgpdump is packaged by Debian (and possibly other distros, too), so check it in the repositories before compiling it yourself.
    – Roman Cheplyaka
    Mar 1, 2014 at 7:33
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    There's a similar to pgpdump but not that verbose output from gpg --list-packets
    – JSmith
    May 21, 2014 at 7:24
0

There is more simple solution (tested for GnuPG 2.2.27):

gpg pubkey.gpg

Or, machine-readable result (some upgrades for @jm3 answer):

gpg --with-fingerprint --with-colons pubkey.gpg
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