72

Ubuntu Doc page says this:

It is advisable that you add the Opera GPG key.

wget -qO - http://deb.opera.com/archive.key | sudo apt-key add -

Where do I add that?

I want to take the advice but I don't know what part of software center to add gpg keys to.

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  • 3
    I believe that is a one line command to enter into terminal – Mateo May 5 '13 at 13:55
  • 1
    .msi in Ubuntu is called .deb. – Alvar May 5 '13 at 17:12
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    As a side note, adding keys you fetch over non-HTTPS breaks any security that signing packages added. Wherever possible, you should download keys over a secure channel (https://). – user304335 Jul 10 '14 at 18:00
89

This a a one line command to enter in terminal. See What is a terminal and how do I open and use it?

To use it, you would paste the entire command in the terminal (remember to use https):

wget -qO - https://deb.opera.com/archive.key | sudo apt-key add -

But of course, it is daunting just copying and pasting commands without knowing what they are doing, and having no instructions on how to undo their actions, so here is a basic breakdown of the commands:

  • wget downloads something from a server. See wget manual for Ubuntu 16.04.
  • | is a pipline, which takes the output of one command and runs it into the input of another
  • apt-key add adds a package key

So it basically downloads the key and then adds it in one command.

I tested the command and it should work.

Now to verify that it worked, run this command (from this answer):

apt-key list

This will list the keys added and the key from Opera should be listed on the bottom like this:

pub   1024D/30C18A2B 2012-10-29 [expires: 2014-10-29]
uid                  Opera Software Archive Automatic Signing Key 2013 <packager@opera.com>
sub   4096g/C528FCA9 2012-10-29 [expires: 2014-10-29]

The linked answer also shows that you can remove the key if needed, using:

sudo apt-key del 30C18A2B

with 30C18A2B being the key-id from the list.

After performing that command, and setting up the sources exactly like in your screen-shot, do:

sudo apt-get update
sudo apt-get install opera

(note there are some random warnings, but nothing that affects the install or software center operations)

And for the removal (just in case): What is the correct way to completely remove an application?

So in summary:

  • Add repository enter image description here
  • Add key with apt-key
  • Install in terminal with apt-get
  • Search in dash enter image description here
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  • 4
    "apt-key adv" allows one to download the key from a public keyserver. – jeremiah Mar 31 '16 at 13:27
  • After adding the key with apt-key add, the .key file (in this case, "archive.key") can be deleted without consequence, right? The key (the information, not the file) has already been added to a list somewhere, so the file should no longer be needed. – Cerran Mar 17 '18 at 20:52
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    @Cerran, correct. APT keeps keys somewhere else (/etc/apt/trusted.gpg.d/ and /var/lib/apt/keyrings/ for example.) – Alexis Wilke Feb 27 '19 at 18:36
  • If you get an SSL error with wget, you can use curl instead: curl -L https://deb.opera.com/archive.key | sudo apt-key add - – rubo77 May 6 '19 at 9:54
29

If you are manually adding a key from a PPA, use

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 00000000

Replacing the 00000000 with the second part of the key informed in the PPA website that you want to add.

For example, if you find this line:

 4096R/7BF576066

Use only the second part (no matter its size), which in this example is 7BF576066

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  • are errors like gpg: keyserver receive failed: No keyserver available and gpg: keyserver receive failed: Connection refused common? – iuridiniz Dec 31 '18 at 13:49
  • No, errors like these aren't common. Maybe you're writing the wrong key. – Paulo Coghi - Reinstate Monica Jan 1 '19 at 14:51
24

Newer versions of apt also support the following:

apt-key adv --fetch-keys http://deb.opera.com/archive.key

This method also provides more detailed feedback as well, e.g.:

gpg: key 7BD9BF62: public key "signing key <username@domain.com>" imported
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)

This also has the added bonus of removing the need for additional dependencies like wget or curl.

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  • 1
    apt-key adv does not seem to work for https – danihodovic Jun 14 '17 at 11:24
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    @dani-h You need gnupg-curl to use HTTPS if you are using GPG 1.x. – Tao Wang Oct 27 '17 at 5:08
  • apt-key adv --fetch-keys will only fetch one key from the URL, and if the URL contains multiple keys, please use wget | apt-key add instead. – Tao Wang Oct 27 '17 at 5:11
  • It seems to work with https already (just tested on Ubuntu 17.10) – user1182474 Dec 9 '18 at 19:25
0

Another way where you just have an .asc key, you download the .asc key and add it to the keyring.

For instance - 

curl -L https://packages.riot.im/debian/repo-key.asc | sudo apt-key add -
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