Michael Schierl - 2011-10-23

This request is quite pointless for open source archivers, since there is no technical way to prevent anyone from downloading the source code, removing the time check and compiling it again. With password protection, you can use AES (so that the file content will depend on the password so you cannot uncompress it without password), but time based there is no such way.

The best option for you would be to create an SFX archive with 7-zip and use a closed-source (commercial) self-decryption tool that provides this option. At least as long as nobody has cracked the decrypting tool (which basically means the authors have to change the algorithm regularly, just with any other crypter used for protecting intellectual property), you will be safe. But depending on what you have compressed, it might be cracked quickly which will mean that if the archive is older than a few months it is "possible" again to decrypt it...