SecureZIP for Mac from PKWARE, Inc., lets you create ZIP archives and open them, even if they are encrypted or digitally signed. When a file is encrypted, you must have an appropriate credential (either a passphrase or digital certificate) to open it.
This document will help you use SecureZIP to work with any ZIP archive on your Mac.
Using the 30-Day Trial and Activating SecureZIP
About Strong Encryption
Setting SecureZIP Preferences
Unzipping ZIP Files
Zipping Files into a New Archive
SecureZIP Enterprise Features