gpg

Generate a new key pair

$ gpg --gen-key

$ gpg --list-keys

$ gpg -e -r [recipient_email] [file]

$ gpg -d [file.gpg]

$ gpg --sign [file]

$ gpg --verify [file.sig]

$ gpg --export -a "[user_id]" > [public.key]

$ gpg --import [public.key]

gpg [--homedir dir] [--options file] [options] command [args]

gpg (GNU Privacy Guard) is a complete and free implementation of the OpenPGP standard as defined by RFC 4880. It allows encrypting and signing data, features a versatile key management system, and provides access modules for public key directories.
GPG supports both symmetric (password-based) and asymmetric (public/private key) encryption. Common use cases include encrypting sensitive files, signing email messages, verifying software package authenticity, and establishing secure communication channels.

-e, --encrypt

Encrypt data to one or more recipients

Decrypt data (default if input looks encrypted)

Make a signature

Verify a signature

Encrypt with symmetric cipher using a passphrase

Encrypt for the specified recipient

Use specified key as the key to sign with

Create ASCII armored output

Write output to specified file

Generate a new key pair

Generate a new key pair with dialog for all options

List all keys from the public keyrings

List all keys from the secret keyrings

Import keys from a file

Export keys from the keyring

Remove keys from the public keyring

Remove keys from the secret keyring

List keys and their fingerprints

Specify keyserver to use

Send keys to a keyserver

Import keys from a keyserver

Batch mode, never ask for input

Assume yes on most questions

Use specified passphrase

~/.gnupg/gpg.conf

User configuration file for default options, keyserver settings, and algorithm preferences.

Public keyring database storing imported and generated public keys.

Trust database for the web of trust model.

Key management is critical; losing your private key or forgetting the passphrase means permanent loss of access to encrypted data. The web of trust model requires careful key verification to prevent man-in-the-middle attacks. Default algorithms and key sizes should be reviewed periodically as cryptographic standards evolve.

GPG was first released in 1999 by Werner Koch as a free software replacement for PGP (Pretty Good Privacy). It was developed as part of the GNU Project and has since become the de facto standard for email encryption on Unix-like systems. GPG 2.0 introduced a modular architecture in 2006, and version 2.2 brought improved default algorithms and keyserver handling. The project continues to be actively maintained and is widely used by journalists, activists, and security-conscious users worldwide.

ssh(1), openssl(1), age(1), sha256sum(1)