GnuGP
Encrypt a file with a passphrase
gpg -o file.txt.gpg -c file.txt
Note: -c is equivalent to --symmetric
Show encryption used in a gpg file
gpg --list-packets -vv --show-session-key file.gpg
Show fingerprint of private key with no import
gpg --with-colons --import-options show-only --import --fingerprint < secret.asc | awk -F: '$1 == "fpr" {print $10;}'
Show a gpg file in armored format
gpg --enarmor < file.gpg