gpg error fix

[Mika Suomalainen]

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05.05.2012 01:51, Verde Denim kirjoitti:
> I setup Ubuntu 12.04 on a new machine today and in the course of 
> updating apt got a GPG error for ppa.launchpad. After some 
> googling, I was able to find this fix -
> 
> 1) gpg --keyserver keyserver.ubuntu.com 
> <http://keyserver.ubuntu.com> --recv <last 8 digits of key>

This command downloads the GPG key from launchpad.

> 2) gpg --export --armor <last 8 digits of key> | sudo apt-key add 
> -

This command exports the gpg key in ASCII format and adds it to apt's
keyring.

> But wanted to know why this works. A brief explanation would be 
> most helpful; thanks.

Apt uses GPG to check that the packages, which it installs aren't
modified or corrupted after they were created. To check the GPG
signature of package, it need the public key of the signer of package.

You can test it with this email. Run "gpg" in terminal and copy-paste
this email into it. First it complains about missing public key 82A46728.
Then get my key from keyserver by running "gpg --keyserver
keyserver.ubuntu.com --recv-keys 82A46728" and run gpg again and paste
this email to it. Now it should tell you "Good signature from user
Mika Suomalainen" and warn you that my key isn't signed by my key.
I think that Apt receives similar error message if it cannot check the
validity of package.

I hope that this helps.

PS. If I am wrong in some part, please correct me.

- -- 
Mika Suomalainen
gpg --keyserver pool.sks-keyservers.net --recv-keys 4DB53CFE82A46728
Key fingerprint = 24BC 1573 B8EE D666 D10A  AA65 4DB5 3CFE 82A4 6728

Please don't toppost, if possible
https://wiki.debian.org/FAQsFromDebianUser#What_is_top-posting_.28and_why_shouldn.27t_I_do_it.29.3F

Please don't send HTML, if possible. It's possible with most of
clients, even with webmails, see:
https://wiki.debian.org/DebianMailingLists#HowTo_send_plain_text_emails_to_the_list

I use GPG/INLINE, because some mailing list programs modify the headers
of messages and this way make signature.asc files (PGP/MIME)
unverifiable. Please remove lines about beginning and ending GPG
signature blocks in your replies to messages, which are sent by me.
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