Securely Encrypt Files with WinZip

WinZip allows you to encrypt files by placing them in an encrypted archive. If you must send sensitive data over insecure channels, such as e-mail, then it is required you use WinZip (or an equivalent encryption scheme) to protect the data while in transit.

Make Sure WinZip is using Strong Encryption

Strong Encryption is defined as encryption using a 128-bit (or higher) encryption key.

Older versions of WinZip used a much more insecure encryption method that does not meet minimum Columbia University Encryption Policy standards. Even though newer versions of WinZip offer encryption protection above and beyond 128-bits, in order to maintain compatibility with older versions, many of WinZips out-of-the-box settings default to the older legacy modes. You may have to change the default Encryption setting to an appropriate level.

In order to ensure that WinZip is using Strong Encryption, please follow these steps:

  1. Open WinZip (It can usually be found in Start -> Programs)
  2. Click on the Settings Ribbon.
  3. Under Encryption, set the Level to either "AES (128-bit)" or "AES (256-bit)".
  4. That's it. From now on all encrypting you do with WinZip will be sufficiently secured.

Encrypting With WinZip

WinZip provides two alternatives for encrypting files.

The most efficient way to encrypt files is to do so while you are adding them to a Zip archive (.zip or .zipx). To encrypt files while they are being added:

  1. Check the Encrypt added files check box in the Add dialog. Before adding the files, WinZip will display the Encrypt dialog
  2. Choose the password and desired encryption method

When you choose to add files to an existing archive, there is no Add dialog and therefore no opportunity to encrypt the files while they are being added. In these cases, you can encrypt files after they have been added. To do so:

  1. Open the Zip file in the Classic interface
  2. Click Encrypt on the Actions menu



You can also encrypt an entire Zip file AFTER it's already been created.

  1. Right click on the Zip file in My Computer, Windows Explorer, or Computer (in Vista)
  2. Select WinZip
  3. Select Encrypt

In either case, WinZip will ask for a password and encryption method and then encrypt all files currently in the Zip archive.

If a file in the Zip archive is already encrypted, it will first be decrypted and then re-encrypted using the password and encryption method you specified. WinZip will first try to decrypt the file using the current password. If the file cannot be decrypted with this password, WinZip will ask you for the correct password. If you are unable to supply the correct password, the file can be skipped, and it will remain unchanged in the Zip archive. The password you entered in the Encrypt dialog box will remain active until either you delete or replace it, or you close the archive.


You can also download the WinZip Encryption Step-By-Step (PDF)