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Gpg

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Reference:wiki.archlinux.org

Initial setup ​

On your shell's rc file, export the GPG_TTY environment variable:

shell
export GPG_TTY=$(tty)

Configuration ​

To apply any configuration changes, run this command:

shell
gpg-connect-agent reloadagent /bye

If for some reason, password prompt does not appear (i.e. because of CTRL+c in a prompt), try:

shell
pkill -KILL gpg-agent

Pinentry ​

Optionally set the dialog for inputting your password. Check the available front-ends and dependencies with:

shell
ls -1 /usr/bin/pinentry*
pacman -Qi pinentry

Add your choice to ~/.gnupg/gpg-agent.conf, for example:

txt
pinentry-program /usr/bin/pinentry-qt

Cache timeout ​

Value set in seconds, default-cache-ttl is the value that will extend the timeout each time the cache is used, and max-cache-ttl is the maximum value it can be extended.

Example for 1 day:

ini
default-cache-ttl 86400
max-cache-ttl 86400

Use 0 to disable caching.

Usage ​

shell
gpg OPTIONS FILE

INFO

If FILE or -o is not specified, stdin and stout will be used, respectively.

Common usage options:

OptionDescription
-K --list-secret-keysList secret keys.
-c --symmetricEncrypt a FILE using symmetric cipher.
-d --decryptDecrypt the FILE. Output to STDOUT by default.
-e --encryptEncrypt data to one or more public keys. Output to $FILE.gpg by default.
-k --list-keys --list-public-keysList public keys.
-o --outputWrite output to FILE.
-r --recipientEncrypt for user id NAME. Often used with --encrypt.
-s --signSign a message.
--default-recipient-selfUse the default key as default recipient if option --recipient is not used.
--keyid-format shortDisplay key IDs with 8 characters (used on git and pass).
--verifyVerify the FILE's signature.

Key management:

OptionDescription
-a --armorCreate ASCII armored output (key.asc).
--delete-keys NAMERemove key from the public keyring.
--delete-secret-keys NAMERemove key from the secret keyring.
--export [KEYID!]Export keys (usually used with -a and --output).
--export-ownertrustExport ownertrust values.
--export-secret-keys [KEYID!]Export secret keys (usually used with -a -o).
--full-generate-keyGenerate a new key pair.
--import FILEImport keys.
--import-ownertrust FILEImport ownertrust values.

Keyserver:

OptionDescription
--gen-revoke FILEGenerate a revocation certificate.
--recv-keys KEYIDImport keys from a keyserver.
--search-keys NAMESearch the keyserver for the given names.
--send-keys KEYIDExport keys to a keyserver.

Encrypt and decrypt ​

Encrypt with symmetric cipher:

shell
gpg -co file.txt.gpg file.txt

Encrypt and sign to someone/self with:

shell
gpg -o file.txt.gpg -esr 'Recipient Name' file.txt         # `-o` is optional in this case
gpg -o file.txt.gpg -es --default-recipient-self file.txt  # `-o` is optional in this case

Encrypt and redirect the data (-o - is needed):

shell
gpg -o - -e --default-recipient-self file.txt > ~/result.gpg  # Just override output file

Decrypt (and show signature) with:

shell
gpg -o file.txt -d file.txt.gpg

Compress and encrypt folder:

shell
tar --zstd -c Folder/ | gpg -e --default-recipient-self > folder.tar.zst.gpg

Decrypt and extract folder:

shell
gpg -d folder.tar.zst.gpg | tar --zstd -x

Verify file signature ​

Check the signature only (will not work if file is encrypted):

shell
gpg --verify file.txt.gpg

Given a signature file .sig and the data/binary file you want to check (ex: .efi):

shell
gpg --keyserver-options auto-key-retrieve --verify ipxe-arch.efi.sig ipxe-arch.efi

Key management ​

shell
gpg --edit-key IDENTIFIER
list    # Listing keys
key 0   # Select key (0 is master)
trust   # Trust a key
addkey  # Add subkey
delkey  # Delete subkey
passwd  # Change passphrase
expire  # Change expire date
save    # Save changes

Add new user info with:

shell
gpg --edit-key IDENTIFIER
adduid
save

Optionally revoke the old user:

shell
gpg --edit-key IDENTIFIER
uid N
revuid
save

Generate ECC master key ​

shell
gpg --expert --full-generate-key
# (9) ECC and ECC
# (1) Curve 25519

Optionally generate sign key:

shell
gpg --expert --edit-key IDENTIFIER
addkey
# (10) ECC (sign only)
# (1) Curve 25519
save

Advanced ​

Delete master key ​

shell
## Find master key keygrip
gpg --with-keygrip --list-key MASTERKEYID

## Securely delete it from .gnupg folder
shred --remove ~/.gnupg/private-keys-v1.d/KEYGRIP.key