How do you encrypt files in a Zip file 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 file (.zip or .zipx).
WinZip ribbon interface
If you are creating a Zip file in a folder window using the context menu (right click), you will have an option to encrypt the files if the Add dialog is displayed. If you choose to add files to an existing Zip file using Add to recently used Zip file there will be no Add dialog and therefore no opportunity to encrypt the files while they are being added. In such a case, you can encrypt files after they have been added.
To encrypt files already in a Zip file:
In either case, WinZip will ask for a password (and encryption method if you are using the Classic interface) and then encrypt all files currently in the Zip file.
If a file in the Zip file 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 file. The password you entered in the Encrypt dialog box will remain active until either you delete or replace it, or you close the archive.