why not just use openssl or another command line tool?
To encode: openssl aes-256-cbc -a -salt -in secret.zip -out secret.zip.enc
To decode: openssl aes-256-cbc -d -a -in secret.zip.enc -out secret2.zip
To encode: openssl aes-256-cbc -a -salt -in secret.zip -out secret.zip.enc
To decode: openssl aes-256-cbc -d -a -in secret.zip.enc -out secret2.zip