148

I don't need the key in my server's keyring anymore. Is it possible to remove it? I added the key using this command:

 curl http://repo.varnish-cache.org/debian/GPG-key.txt | apt-key add -

Thanks for helping

  • I found this question useful because currently Ubuntu 18.04 GUI called Software & Updates-->Authentication don't seem to work (it can't remove any trusted software key). Instead, the cli cmds given below had to be used. – Sun Bear Aug 19 at 8:07
201

First you need to find the key id of the key you added. Do this by the command:

sudo apt-key list

It will list all the keys that you have, with each entry looking like this:

pub   1024R/B455BEF0 2010-07-29
uid                  Launchpad clicompanion-nightlies

Once you have figured out which key to remove, use the command sudo apt-key del <keyid> where <keyid> is replaced with the actual keyid of the key you want to remove from your keyring.

$ sudo apt-key del B455BEF0
$ apt-key list | grep clicompan
$
  • @Raymond No problemo :) – Nitin Venkatesh Feb 24 '12 at 20:15
  • 1
    Ah I see the unique Id is on the line labelled pub, not the line labelled uid. – ctrl-alt-delor Jun 21 '16 at 7:59
  • 6
    on ubuntu 16.10 results seems a little different : pub rsa4096 2012-05-11 [SC] 8439 .... uid .... – mxdsp Nov 6 '16 at 16:17
  • Looks like this needs to be updated for 18.04 – kennyB Feb 16 at 0:12
  • After deleting the key, I encountered a new problem The following signatures couldn't be verified because the public key is not available: NO_PUBKEY, what should I do next ? – Corey Aug 27 at 3:10
131

On 16.10 the short key id is no longer shown when you use the list command, but it is actually the last 8 characters of the long hex.

So for example the key id for the following key

/etc/apt/trusted.gpg.d/ubuntu-keyring-2012-cdimage.gpg
------------------------------------------------------
pub   rsa4096 2012-05-11 [SC]
      8439 38DF 228D 22F7 B374  2BC0 D94A A3F0 EFE2 1092
uid           [ unknown] Ubuntu CD Image Automatic Signing Key (2012) <cdimage@ubuntu.com>

The key id will be EFE21092

  • 17
    Very helpful, thank you. This is extremely unhelpful UX. – SColvin May 18 '17 at 11:27
  • 12
    @SColvin you can just do sudo apt-key del "8439 38DF 228D 22F7 B374 2BC0 D94A A3F0 EFE2 1092" and I think it is safer to use the whole fingerprint, the keyid could have duplicates (at least when you use PGP for emails, I read you should share your whole fingerprint and not just the keyid). – baptx Dec 2 '17 at 12:14
  • 1
    Very helpful, very true also for 17.10! – Hartmut P. Apr 13 '18 at 21:15
  • 2
    And for 18.04.1. – Russ Bateman Oct 3 '18 at 20:45
  • Thank you. Awful design decision. – Brian Smith Mar 25 at 19:54
4

I made a short script to make things easier and using a string instead of the id.

You can use my script if the key contains a unique string you know.
e.g. in my case for webmin

pub   1024D/11F63C51 2002-02-28
uid                  Jamie Cameron <jcameron@webmin.com>
sub   1024g/1B24BE83 2002-02-28

I'm sure only the webmin key on my system has jcameron than I use this script to remove the according key.

I saved it as ~/removeAptKey

and run it as

sudo ./removeAptKey jcameron

The ouput should be something like

KEYID: 11F63C51
OK

Here is my script:

#!/bin/bash

function printKeys(){
    echo "Installed keys are"
    echo ""
    sudo apt-key list
}

if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi

if [[ $# -eq 0 ]]
then
    echo "No key name provided"
    exit 1
fi

UNIQUE=$1

sudo apt-key list | grep "${UNIQUE}" -B 1 > result.temp

LENGTH=$(cat result.temp | wc -l)

if [[ ${LENGTH} -gt 2 ]]
then
    echo "Attention you found more than 1 key. Use a more specific string."
    printKeys
    exit 2
fi

if [[ ${LENGTH} != 2 ]]
then
    echo "Key not found. Doing nothing."
    printKeys
    exit 3
fi

KEYID=$(cat result.temp | grep 'pub' | cut -d " " -f 4 | cut -d "/" -f 2)
echo "KEYID: "$KEYID

apt-key del ${KEYID}

rm result.temp

First I get the upper two lines of my key's block:

  • sudo apt-key list: lists the apt keys as usual
  • grep '${UNIQUE}' -B 1: take only the line containing the unique key string jcameron and -B 1 the line before
  • > result.temp: Save it in a file (which is later removed)

If this returns exactly 2 lines (-> got exactly 1 key) I move on:

  • grep 'pub': Now take only the line with the pup key id
  • cut -d " " -f 4: take the 4th word of that line (the first is pub than come two spaces, than the string we are after ``)
  • cut -d "/" -f 2: take only the part after /

And finally delete this key and cleanup

  • apt-key del ${KEYID} (in my case 11F63C51)
  • rm result.temp: don't need this file anymore
  • I ran this without a parameter and it just wiped out all my keys. ;( – Gabriel Fair Dec 21 '18 at 23:11
  • If anyone else has their keys wipped, I was able to fix it by following these instructions: askubuntu.com/a/145933/13693 – Gabriel Fair Dec 22 '18 at 2:29
  • Hu? How did this happen? It should exit with an "No key name provided" if there was no parameter.. – derHugo Dec 22 '18 at 10:49
  • @derHugo not sure but could it be that the # in that if clause is the culprit? – defuzed Apr 9 at 15:51
  • @defuzed if you mean $# then no. It returns the amount of given parameters. – derHugo Apr 9 at 17:51
2

I know I might be late, but just wanted to share this one-line command to achieve this.

NOTE: This will only work if the output is an unique key.


Ubuntu versions up to 16.04 (UPDATED 2018-12-22):

apt-key del $(apt-key list | awk 'NR=='$(apt-key list | grep --line-number --regexp "FOOBAR" | cut --fields 1 --delimiter ":")'{print;exit}' | awk '{print $2}' | cut --fields 2 --delimiter "/")

where FOOBAR is the UID name.


Ubuntu versions from 16.10:

apt-key del $(apt-key list | awk 'NR=='`expr $(apt-key list | grep --line-number --regexp "FOOBAR" | cut --fields 1 --delimiter ":") - 1`'{print;exit}')

where FOOBAR is the UID name.

  • 1
    I'm not sure why, but I got an error when I tried to run the 16.04 command you provided. awk: line 1: syntax error at or near { But the angle braces match, so I'm not sure why this doesn't work – Gabriel Fair Dec 21 '18 at 22:45
  • @GabrielFair Thanks for noticing, back in june it has been working (I copy-pasted it from my console) but now seems that has been updated and the apt-key list format has changed. Now it seems to be working again. (EDIT: Remember to run this as superuser) – David Tabernero M. Dec 22 '18 at 0:47

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