As powerful and robust as encryption applications are, they tend to suffer from a common defect. If you encrypt something with them and pass it on to someone else, the person on the receiving end usually needs the encryption program to decrypt it. That limits the usefulness of the encryption, since it's not always practical to pass along a copy of the program in question. If you're doing the encryption in a one-time fashion, it's an even less practical solution.
One of the more intelligently implemented solutions to this problem is a free application called Steganos LockNote. LockNote is a simple encryption text editor, somewhat like Notepad, which saves documents created in the program as self-decrypting executables. The saved executable is encrypted with a password, so in order to run the program (and thereby open the file), you need to have the password -- it's not possible to reveal the message by inspecting the file with a hex dump, for instance.
The program uses an AES 256-bit encryption algorithm, which makes it extremely difficult to break (to put it mildly!), implemented from an open-source cryptographic library that's withstood heavy scrutiny. The program itself does not need to be installed; it's completely self-contained and can be copied anywhere and run from anywhere (such as a USB drive).
There are, however, a few things missing. For one, it's not possible to encrypt a note as read-only; it would be handy to be able to do this for messages that you want passed around and not edited. One way to partly get around this limitation would be to attach a digital signature in the message itself, which would reveal evidence of tampering, but that requires that the person reading the message has the ability to verify digitally signed messages in the first place.
About the author: Serdar Yegulalp is editor of the Windows Power Users Newsletter. Check it out for the latest advice and musings on the world of Windows network administrators -- and please share your thoughts as well!