PGP and GPG Cheat Sheet

Some backgrounds

PGP: Stands for pretty good privacy.

GPG: Stands for GNU privacy guard.

PGP was originally developed as a copyrighted freeware under GNU public license but was later made into propriety software because of the USA export laws.

GPG was a re-write and stripped of any proprietary encryption algorithms version of PGP. It was developed by the GNU community.

As of 2022, GPG is recommended for all developers.

For GitHub users, there is also SSH key. How does it differ from GPG key?

Well, there are two main differences.

SSH key is used to validate accesses for GitHub repositories.

GPG key, on the other hand, is for verifying commits.

You may search keys by email address or Key ID at keys.openpgp.org

Usage

Generate keys


# quick and dirty
gpg --gen-key
# more options
gpg --full-generate-key

List keys


# list public keys
gpg --list-keys
# list secret keys
gpg --list-secret-keys

Export public key


# gpg --export --armor _<pub/uid>_ > pubkey.asc
gpg --export --armor yanbc > yanbc.pubkey.asc

Import a key from your friend


gpg --import yanbc.pubkey.asc

Edit key

This is a more advanced usage. You can make changes to a key, e.g. trust/disable/delete a certain key, with the following command


# gpg --edit-key _<pub/uid>_
gpg --edit-key yanbc

This will open up a prompt terminal. Type help for all sub-commands.

Encrypt a file


# create a file
echo hello > hi.txt
# encrypt the file for yanbc and yourself
gpg --encrypt --recipient yanbc --recipient your_user_name hi.txt

Decrypt a file


# decrypt to file
gpg hi.txt.gpg
# decrypt to stdout
gpg --decrypt hi.txt.gpg

Backup keys


# backup public keys
gpg --export-options backup -o PATH/TO/BACKUP/keyring.gpg --export
# backup secret keys
gpg --export-options backup -o PATH/TO/BACKUP/keyring.gpg --export-secret-keys

Restore keys


gpg --import-options restore --import PATH/TO/BACKUP/keyring.gpg

References

How does the key server work?