SPac - Easy to use, secure, and powerful application for file encryption and sharing.

In addition to compression and encryption SPac has a unique, we think, feature that makes it simple to protect and share sensitive files. Any SPac package can be converted into a self-extracting archive with a difference. The difference with SPac over similar tools is that the recipient of your package can add, delete, and modify files in the package as well as simply extracting them. This is achieved by embedding a cut-down version of SPac in the package.

This means that your sensitive files need never exist permanently on disk, while still allowing trusted friends and associates the ability to modify them. Once the user has supplied the required password, they can modify the files simply by double-clicking on them, the changes will then be encrypted and stored back in the archive, and the working file will be wiped from disk.