Zip files can be password-protected, but the standard Zip encryption
scheme is extremely weak. If your operating system has a built-in way to
encrypt zip files, you probably shouldn’t use it.
To gain the actual benefits of encryption, you should use AES-256 encryption. 7z archives support this natively, but you can also encrypt Zip files with AES-256 encryption.
Zip 2.0 Legacy Encryption vs. AES Encryption
There are actually two types of Zip file encryption. The older Zip
2.0 encryption is extremely insecure, while the newer AES encryption is
fairly secure.
Unfortunately, many pieces of software — particularly operating
systems with built-in support for Zip files — don’t support the newer
AES encryption standard. This means that using the Zip
password-protection features found in Windows XP, current versions of
Mac OS X, and even typical Linux desktops won’t give you securely
encrypted Zip files. Even some third-party utilities are reluctant to
switch to AES for their Zip encryption as it means those AES-encrypted
zip files will then be incompatible with the built-in Zip features in
Windows, Mac OS X, and other software.
It’s still possible to get AES encryption with Zip files — but such
files will require third-party software to view, anyway. You may
just want to use a different archive format, such as 7z. The 7z archive
format requires strong AES-256 encryption. Whenever you create a
password-protected 7z file, you know that it’s securely encrypted.
Really, 7z is great — it came out on top in our file-compression benchmarks. It’s generally on the top of other file compression benchmarks we’ve seen, too.
Windows – 7-Zip
Windows offers a built-in way to create Zip files. Windows XP even
offered a way to password-protect and encrypt these Zip files. However,
Windows XP used the extremely insecure “standard” zip file encryption
algorithm. Even if you’re still using Windows XP, you shouldn’t use this feature. Later versions of Windows dropped the password-protection option entirely.
Nearly every popular encryption utility offers this features. We like
7-Zip, which is completely free and open-source, so it won’t try to nag
you for any money.
With 7-Zip installed, you can select some files in a File Explorer or
Windows Explorer window, right-click them, and select 7-Zip > Add to
archive. Be sure to select the “Add to archive” option, as it gives you
the ability to set a password. If you don’t see the menu option here,
you can also open the 7-Zip application directly and use it to create an
archive.
7-Zip will create a 7z archive by default, but you can also choose
Zip. If you do opt to go with Zip, be sure to select the AES-256
encryption method instead of the weaker ZipCrypto method. Enter your
password into the provided boxes and click OK to create your encrypted
archive file.
Mac – Keka
Mac OS X also provides an easy way to create Zip files from a Finder
window, but there’s no way to encrypt a zip file with the graphical user
interface. The zip command included with Mac OS X does offer a way to
encrypt zip files without using any third-party software. However, like
the password-protection feature built into Windows XP, it uses the old
and insecure standard zip encryption scheme. If you really wanted, you
could use the “zip -e” command in a Terminal on a Mac. However, we
strongly recommend against this.
As on Windows, you’ll once again need a third-party file compression app for secure compression. Keka
seems to be one of the most well-loved file compression and
decompression apps for Mac, and we can recommend it. However, even Keka
doesn’t use AES for encrypting Zip files by default. You can get the
currently-in-beta version of Keka and enable a hidden option to do this, or just use the standard version of Keka and create encrypted 7z files instead.
Launch Keka, select 7z, and enter a password for your archive. (If
you select Zip, be sure you have the correct version of Keka and that
you’ve enabled the hidden option above to get the secure encryption.)
Drag and drop one or more files you want to compress onto the Keka
window and they’ll be compressed into a 7z file encrypted with the
password you provided. You’ll need the password to access the file’s
contents in the future.
Linux – File Roller with p7zip-full
The standard Archive Manager (File Roller) application included with
Ubuntu and other GNOME-based desktop environments does have an option to
create password-protected zip files. However, the underlying zip
command used still uses the old, weak encryption instead of strong AES
encryption. Thankfully, File Roller can be used to create encrypted 7z
archives.
To enable this option, you’ll first need to install the p7zip-full
package. (On some Linux distributions, it may just be called p7zip
instead.) For example, on Ubuntu, you can either open the Ubuntu Software Center, search for p7zip-full and install it, or open a Terminal window and run the sudo apt-get install p7zip-full command.
Once you have, you can create encrypted 7z files directly from the
File Roller window. Select some files in a file manager window,
right-click them, and select Compress — or open the Archive Manager
application directly and use it to create a new archive.
In the Compress window, be sure to select the 7z archive format.
Click the Other Options header and provide a password. The password will
be used to unlock your archive later.
There are many different software programs for creating
password-protected archives, but — whatever you use — be sure it’s using
secure encryption. The problem with Zip encryption isn’t purely
theoretical. The web is full of tools that can “recover” a
password-protected zip file that was created using the old encryption
scheme. “Recover” is a less-scary word for breaking and removing the
encryption.
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