Protect your data: File encryption

You have data that needs to be secured. Don’t shake your head and say “No I don’t”. Yes, you do. It could be your “special” text file that you keep your passwords in or that Excel spreadsheet you’ve been keeping track of your finances on. Either way, it needs to be protected with encryption.

What is encryption? According to the Wikipedia entry, encryption is “the process of obscuring information to make it unreadable without special knowledge.”. In the case of your data files, the special knowledge is (1) the program used to encrypt/decrypt the files and (2) the passphrase that unlocks the files (i.e. allows decryption).

My software of choice for encrypting files on a Windows system is AxCrypt (free & open source). The reason I chose it over other encryption programs, like TrueCrypt, is it’s ease of use from an “Average Joe/Jane user” perspective. There is no (zero) configuration needed and encryption/decryption commands can be started from the right-click context menu.

Some of the features of AxCrypt include:

Encrypt/decrypt using either a passphrase or a key file.
AES encryption with 128-bit keys
No need to decrypt a file in order to edit/run it. Just double-click the file, type your passphrase and the file will open in the default application. If the file is edited and saved, it will be saved as the encrypted file (unless directed to save as a different file).
Secure memory handling – no keys or data in the paging file.
Original file name can be scrambled when the file is encrypted. Just right-click the file and go to AxCrypt -> Rename. The original file name will be restored when the file is decrypted.
Encrypt as an .EXE file. Send this file to anyone and they can open it without having AxCrypt installed. All they need is the the correct passphrase or key file.

To get the best encryption level possible, create a key file (right-click a file, AxCrypt -> Make Key-file) or use a passphrase that is at least 10 random characters (alphanumeric) long. Remember, weak passphrases equal weak protection.

If you create a key file, you will get a passphrase that is 44 characters long, like this:

Gf80 94eA VcS7 VgT3 1Dsc iVIs pJ+C 6201 87X/ ggSC e/s=

In case you’re wondering, no, that isn’t the sequence in my key file. You can store the key file on your hard drive but it would be better to put it on a USB drive or a floppy disk. Don’t just leave those lying around! The key file can be used many times, you don’t have to make a new one for each file you encrypt.

System requirements or limits:

5 MB virtual memory when running (encrypting/decrypting)
2 MB disk space (installation)
Temporary disk space needed during encryption: Up to 1.5x the size of the file(s).
Windows 95/98/ME/NT/2K/XP
File size limit: 500 – 700 MB in Win 9x/ME, no limit except disk space on NT/2K/XP.
Max number of encrypted files only limited by the amount of disk space.

Screenshots
Encrypting the file:

Encrypted file:

Decrypting the file:

Renamed (original name restored upon decryption):

(Article 2, Day 2)

22.Mar.06 Security, Software, Technology

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4 Responses to “Protect your data: File encryption”

Lineman | March 22nd, 2006 at 9:02 pm
Very cool. I’ll have to try this one.
Poe | March 23rd, 2006 at 12:14 am
I can honestly say that I have nothing to encrypt. I keep no personal information on any of my machines.
Lineman | March 23rd, 2006 at 5:08 am
Are you writing it all down? Maybe it should be on your computer.
Poe | March 23rd, 2006 at 3:10 pm
I keep it all in my head… I think. Wait, what were we talking about again?