Protecting files with encryption

PowerZip 7 offers several encryption options to allow you to password-protect your files from unauthorized access.

About Encryption
When the encryption option is selected (see below) you are prompted to enter a password. PowerZip generates an encryption key from this password. PowerZip then enciphers the files being compressed with the encryption key before storing them in the Zip file. Because the files are stored in the encrypted form, the original encryption key (and therefore the password) is needed to unzip them.

IMPORTANT: Please read the warnings at the end of this page before using encryption. The warnings contain important information and advice. Failure to follow it can lead to permanent data loss, security compromise and/or compatibility problems.

Using Encryption
To use encryption, follow the normal steps to create a Zip file or add files to an existing Zip file but select the "Protect files with a password" option in the Options step of the Compression Wizard. You will be prompted to select the type of encryption and to enter the password that will be used to encrypt the files.

You can also quickly encrypt files directly from Windows Explorer / My Computer. Simply right-click on the file you wish to encrypt and choose "Encrypt". You will only be prompted for the encryption type and password; default compression options will be used.

Compatibility Warning
PowerZip supports two encryption methods - standard Zip encryption and AES encryption. Standard Zip encryption is backward compatible with older versions of PowerZip and with most other Zip programs but does not offer good security. AES offers a high level of data security but you may not be able to unzip files encrypted with AES with older versions of PowerZip or with other Zip programs.

Important warnings about encryption

1. As is always the case with PowerZip, when zipping files with or without encryption, PowerZip stores the compressed / encrypted files in the Zip file of your choice but (by default) leaves the original file(s) intact. This means that if you encrypt a file, the encrypted file will be stored in the Zip archive you create but the original will be left as it was. Therefore, if you encrypt files to stop other people with access to your computer from being able to view them, you have to delete the originals after compression.

The Compression Wizard has an option to automatically delete the original files after compression (in the Options step) but to protect you from possible data loss, this option is always turned off by default. If you wish to use it, you have to explicitly select it each time you compress / encrypt files.

2. If you forget a password, it may not be possible to recover the encrypted files. Standard Zip encryption is considered weak so if you encrypt files with standard Zip encryption and forget the password, it may be possible to recover the files using a Zip password recovery tool (please note that such a tool is not included with PowerZip). If you use AES encryption and forget the password, it will generally not be possible to recover the encrypted files. Therefore, please choose a password that you will remember and/or write it down and store it in a secure place.

3. The security of your files (especially if AES is used) depends to a very large extent on the strength of the password you choose. Because of the large key length employed with AES, an ideal password should be quite long. In fact, a pass-phrase is desirable. To take full advantage of 256-bit AES, a very long pass-phrase (> 50 characters) is required. In practice, you probably won't need that level of security. Nevertheless, we recommend you follow the recommendations below when choosing your password:

  • Avoid using birthdays, telephone numbers and other easily-guessable passwords
  • Try to use mixed case, digits, and special characters (such as $, *, -, #, @ etc).
  • Avoid using English words (or words from another language). If you use words, embed digits or special characters in them e.g. dict2ionar$y
  • Avoid using non-ASCII characters such as umlauts or characters from alphabets other than English. While increasing security, using such characters may make it impossible to decrypt your files by Zip programs other than PowerZip or by PowerZip on different machines due to differences in encoding of such characters.
  • Do not use passwords shorter than 8 letters

4. Standard Zip encryption, while being backward compatible, is considered to be very weak. Do not use standard Zip encryption if you require any serious security.

5. Deleting a file (even if the Recycle Bin is emptied) usually doesn't physically delete the file data from disk. It may still be possible to recover the data using special tools.

6. As with all encryption (except One Time Pad variants), AES encryption in PowerZip is not "unbreakable". It is believed that if AES encryption is used, provided a strong password is chosen, it is computationally unfeasible (using techniques currently known) to recover the encrypted data without knowing the password. However, Trident Software Pty Ltd makes no guarantees as to the security of data encrypted with PowerZip. If you require a level of security that would need to withstand cryptanalysis by organizations with considerable resources (such as government agencies or large corporations), you should discuss your requirements with security experts.