7zip

Install p7zip-full packages.

To compress to a 7-zip file:

7za a file.7z myfiles/

To decompress a 7-zip file (preserving directory structure):

7za x file.7z

To compress and encrypt (with password XXXXXXXX) to a 7-zip file:

7za a -mhe=on -pXXXXXXXX file.7z myfiles/

To decrypt, decompress as usual. You will be prompted for the password.