Instructions for exporting/importing (backup/restore) GPG keys

gpg-import-and-export-instructions.md

Every so often I have to restore my gpg keys and I'm never sure how best to do it. So, I've spent some time playing around with the various ways to export/import (backup/restore) keys.

Method 1

Backup the public and secret keyrings and trust database

cp ~/.gnupg/pubring.gpg /path/to/backups/
cp ~/.gnupg/secring.gpg /path/to/backups/
cp ~/.gnupg/trustdb.gpg /path/to/backups/
# or, instead of backing up trustdb...
gpg --export-ownertrust > chrisroos-ownertrust-gpg.txt

NOTE The GPG manual suggests exporting the ownertrust instead of backing up the trustdb, although it doesn't explain why.

Restore the public and secret keyrings and trust database

cp /path/to/backups/*.gpg ~/.gnupg/
# or, if you exported the ownertrust
gpg --import-ownertrust chrisroos-ownertrust-gpg.txt

Method 2

This only really works if you don't mind losing any other keys (than your own).

Export public and secret key and ownertrust

gpg -a --export chris@seagul.co.uk > chrisroos-public-gpg.key
gpg -a --export-secret-keys chris@seagul.co.uk > chrisroos-secret-gpg.key
gpg --export-ownertrust > chrisroos-ownertrust-gpg.txt

Import secret key (which contains the public key) and ownertrust

gpg --import chrisroos-secret-gpg.key
gpg --import-ownertrust chrisroos-ownertrust-gpg.txt

Method 3

This is mainly about trusting my key once I've imported it (by either restoring the pubring.gpg and secring.gpg, or by using --import). This seems to be what I do the most as I either forget to import the trustdb or ownertrust.

Ultimately trust the imported key

This is so that I can encrypt data using my public key

gpg --edit-key chris@seagul.co.uk
gpg> trust
Your decision? 5 (Ultimate trust)

NOTE If I don't trust the public key then I see the following message when trying to encrypt something with it:

gpg: <key-id>: There is no assurance this key belongs to the named user

The trustdb should only be corrupted if the backup is corrupted, I would assume.

Not necessarily. The ownertrust export stores the values in plain text form (fingerprint:level), while trustdb don't. It could be corrupted because of GPG version incompatibilities and a number of other reasons.

Wrote a script to automate the backup. It is at https://git.ricketyspace.net/dip/plain/usr/local/bin/gnupg-backup

Thanks for collecting this, and to everyone else for the thoughtful conversation.

Is method 2 a superset of method 1? Seems method 1 is only one step in method 2.

Any ideas why importing ownertrust from file gives me gpg: error in 'myownertrustfile.txt' line too long ?

Very good! Thanks!

You can simplify Method 3 a little by extending the command to:

gpg --edit-key chris@seagul.co.uk trust quit

There is also a way to run the command in a non-interactive mode:

expect -c "spawn gpg --edit-key chris@seagul.co.uk trust quit; send \"5\ry\r\"; expect eof"

@cmcginty nice usage of expect to automate this!

@atepavicharov Try converting the line endings from CRLF to LF (or vice-versa).

Another way:

echo -e "5\ny\n" | gpg --command-fd 0 --edit-key chris@seagul.co.uk trust quit

Method 1 failed because I had previous run gpg2 --list-keys --keyid-format LONG, which created some files and directories in ~/.gnupg/. Make sure to delete those first, before restoring the .gpg files from the backup.

Regarding Method 1, see What’s new in GnuPG 2.1: Removal of the secret keyring

Thanks for this gist!

Method 2:

A little note for Windows users.

Export
When you exporting (via powershell) the output file will be encoded with BOM. If you try to import this will make the import fail with an error.

gpg: [don't know]: partial length invalid for packet type 63
gpg: read_block: read error: Invalid packet
gpg: import from '.\****.key' failed: Invalid keyring
gpg: Total number processed: 0

To resolve this issue change the encoding of the file to UTF8 without BOM.

Import

Import using git bash.
Git bash and powershell are using different homedirs at my work setup due to roaming profiles.

If you get the following error:

gpg: key abc: public key "xxxx <yourmail@mail.com>" imported
gpg: can't connect to the agent: IPC connect call failed
gpg: error getting the KEK: No agent running
gpg: Total number processed: 1
gpg:               imported: 1
gpg:       secret keys read: 1

Try starting the agent using the following command and retry:
gpgconf --launch gpg-agent

Is the exported private key (symmetrically) encrypted? If not, don't you think it's kind of important as a backup practice?

Is there any difference between gpg and gpg2?

why not just backup entire $HOME/.gnupg directory?

There is no pubring.gpg and secring.gpg in gpg2, probably just backup the whole .gnupg directory. Maybe just ensure that the .gnupg directory's permission and the files inside it are safe, for example permission 600 for private key, etc. cmiiw.

Ref: https://www.gnupg.org/faq/whats-new-in-2.1.html#nosecring

Thanks @dandv!

I use method 1 to restore my ~/.gnupg directory from a backup.

It didn't work at first, I needed to delete the whole directory first prior to the restore!

If you've copied or re-created the ownertrust file you may see error

$ gpg --import-ownertrust chrisroos-ownertrust-gpg.txt
gpg: error in 'chrisroos-ownertrust-gpg.txt': line too long

In which case, confirm that there is a newline at the end of the file.