GnuPG
GnuPG or The GNU Privacy Guard is a complete and free implementation of the OpenPGP standart as defined by RFC4880. GnuPG allow you to encrypt and sign you data and communications. It features versatile key management system, along with access modules for all kinds of public key directories. GnuPG, also known as GPG, is a command line tool with features for easy integration with other applications.
Keys management
Listing keys
gpg --list-secret-keys
Encryption
Encrypt a file
gpg -o <file_name>.gpg --encrypt --recipient <key_email> <file_name>
Encrypt a folder
Archive the directory
tar -cvf <archive_name>.tar.gz <directory_name>
Encrypt the archive
gpg -o <encrypted_file_name>.gpg --encrypt --recipient <key_email> <archive_name>.tar.gz
Decryption
Decrypt a file
Decrypt a file
gpg -o <file_name> --decrypt <file_name>.gpg
Decrypt a folder
Decrypt gpg file into the archive
gpg -o <archive_name>.tar.gz --decrypt <file_name>.gpg
Extract files from the archive
tar -xvf <archive_name>.tar.gz -C <output_dir_name>