Gfilui

I would like to use my Launchpad PGP Key to access my Launchpad PPAs on 2 computers. To do it I need to transfer the key to the other Ubuntu computer. I did found very little support on Ubuntu specific websites so far.

Here is what I did on the original computer:

$ gpg2 --fingerprint
/home/ubuntu-xenial/user/.gnupg/pubring.kbx
--------------------------------------------
pub rsa2048/245FD525 2016-12-16 [SC]
 Key fingerprint = C64F 728F BF5D C5CE 357B D1AE FC8F 1C1C 245F D525
uid [ unknown] my_name <my_e-mail>
sub rsa2048/4D0AABD3 2016-12-16 [E]

$ 
$ gpg2 --list-secret-keys
/home/ubuntu-xenial/user/.gnupg/pubring.kbx
--------------------------------------------
sec rsa2048/245FD525 2016-12-16 [SC]
uid [ unknown] my_name <my_e-mail>
ssb rsa2048/4D0AABD3 2016-12-16 [E]

$ 
$ gpg2 --export -a 245FD525 > Launchpad-GPG-Public-Key.asc
$ gpg2 --export -a 245FD525 > Launchpad-GPG-Private-Key.asc
---> Enter secret passphrase
$ 

On the new computer:

$ gpg2 --import Launchpad-GPG-Public-Key.asc
gpg: keybox '/home/ubuntu-xenial/user/.gnupg/pubring.kbx' created
gpg: /home/ubuntu-xenial/user/.gnupg/trustdb.gpg: trustdb created
gpg: key 245FD525: public key "my_name <my_e-mail>" imported
gpg: Total number processed: 1
gpg: imported: 1
$ gpg2 --import Launchpad-GPG-Private-Key.asc.asc 
gpg: key 245FD525: "my_name <my_e-mail>" not changed
gpg: key 245FD525: secret key imported
gpg: Total number processed: 3
gpg: unchanged: 1
gpg: secret keys read: 3
gpg: secret keys imported: 2
$ 
$ gpg2 --edit-key 245FD525
gpg (GnuPG) 2.1.11; Copyright (C) 2016 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Secret key is available.

sec rsa2048/245FD525
 created: 2016-12-16 expires: never usage: SC 
 trust: unknown validity: unknown
ssb rsa2048/4D0AABD3
 created: 2016-12-16 expires: never usage: E 
[ unknown] (1). my_name <my_e-mail>

gpg> trust
sec rsa2048/245FD525
 created: 2016-12-16 expires: never usage: SC 
 trust: unknown validity: unknown
ssb rsa2048/4D0AABD3
 created: 2016-12-16 expires: never usage: E 
[ unknown] (1). my_name <my_e-mail>

Please decide how far you trust this user to correctly verify other users' keys
(by looking at passports, checking fingerprints from different sources, etc.)

 1 = I don't know or won't say
 2 = I do NOT trust
 3 = I trust marginally
 4 = I trust fully
 5 = I trust ultimately
 m = back to the main menu

Your decision? 5
Do you really want to set this key to ultimate trust? (y/N) y

sec rsa2048/245FD525
 created: 2016-12-16 expires: never usage: SC 
 trust: ultimate validity: unknown
ssb rsa2048/4D0AABD3
 created: 2016-12-16 expires: never usage: E 
[ unknown] (1). my_name <my_e-mail>
Please note that the shown key validity is not necessarily correct
unless you restart the program.

gpg> <Ctrl><D>
$ 
$ gpg --list-keys [user]
gpg: checking the trustdb
gpg: public key of ultimately trusted key 245FD525 not found
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: error reading key: public key not found
$ 

At this stage the process is still incomplete and I still can't use it to sign for uploading packages to my PPAs ...

After running through my notes when I originally created the PGP Key some years ago I found this answer on Ask Ubuntu:

$ gpg --keyserver keyserver.ubuntu.com --recv-keys 245FD525
gpg: requesting key 245FD525 from hkp server keyserver.ubuntu.com
gpg: key 245FD525: public key "my_name <my_e-mail>" imported
gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model
gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
$ gpg --no-default-keyring -a --export 245FD525 | gpg --no-default-keyring --keyring ~/.gnupg/trustedkeys.gpg --import -
gpg: keyring `/home/ubuntu-xenial/[user]/.gnupg/trustedkeys.gpg' created
gpg: key 245FD525: public key "my_name <my_e-mail>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
$ gpg --list-keys [user]
pub 2048R/245FD525 2016-12-16
uid my_name <my_e-mail>
sub 2048R/4D0AABD3 2016-12-16
$ 

Now I can use my Launchpad PGP Key on the other computer.