GnuPG

Links

generate GPG keys (for sign/verify and encrypt/decrypt): gpg --generate-key
list all keys in GPG keyring: gpg --list-keys
list private keys: gpg --list-secret-keys --with-subkey-fingerprints
show fingerprint of key <email>: gpg --fingerprint "<email>"
export public key associated with <email>: gpg --output <mail>.gpg --armor --export "<email>"
import public key from <file>: gpg --import <file>
show encrypted file information: gpg --batch --list-packets <file>.gpg
decrypt (binary, not armored) <file>.gpg: gpg --output <file> --decrypt <file>.gpg