If you are using a version of WinZip that is older than version 9, I urge you to upgrade to version 9 or better. Why? Beginning with version 9, WinZip includes AES encryption. Prior to version 9, WinZip’s encryption algorithm was weak and prone to attack.
With Winzip 9 or better, you can safely encrypt individual files, or entire directories, for transit over e-mail or other means, without fear that anyone else will be able to read the protected data. This, however, is predicated on two important facts:
1. You need to use a strong password when encrypting the archive. Use a password or pass phrase with at least 8, or more ideally, 10, characters.
2. Anyone who can read the WinZip file can see all of the names of the files and directories in the archive. If your file and directory names give away vital information (for instance, a directory named “Merger Companies” containing files such as “General Motors.doc”, “Daimler Chrysler” and “Volkswagon”), then anyone who intercepts your Winzip archive will be able to discern what you or your organization are up to. If your archive contains sensitive file names, then I suggest you “double Zip” your archive to protect your secrets.
Get WinZip here: http://www.winzip.com/