Store your most valuable notes in a LockNote. Hide your everyday notes in a safe place. Application and document in one: the mechanism to encrypt and decrypt a note is part of it. Secure, simple, independent. No installation required.
Wonderful concept, but like a few other reviewers all versions of LockNote that I've tried, including 1.0.5, fail to save your text at least half the time when you close the app. In fact, if you manually Save As and write to a new file, LockNote will ask for a password and create an empty copy of itself. When you close, it will ask if you want to save your changes, even if no changes were made, and again ask for a password. Even after entering your password a total of 4 times, you will usually wind up with an empty LockNote. If it opens without asking for a password, you know it didn't save. I've tried LockNote in everything from Windows 2000 to Windows 7 and it has this same problem in each OS. I love the idea of LockNote and carried it everywhere I went for many years, but I recently realized that it is simply too unreliable to trust with important information. I can't imagine why anyone would need encryption for data that *wasn't* important, so unless these issues are resolved, I don't recommend using LockNote. There are numerous apps that will encrypt a text file and yet are portable, so look elsehwere.
Locknote has a clean simple design. I would be very useful if not for a fatal bug where it occasionally fails to save changes. There is no error message or any other indication that it has failed. I have had it working perfectly for a long period of time and, for no reason, suddenly stops updating changes. If I use "save as" to create a new file, it will continue to work but will eventually fail again for no apparent reason.
Be careful - LockNote silently fails to save data. You can tell by watching the Modified timestamp ... when it fails it doesn't change. I lost critical banking login details. I am using KeePass now, which isn't great for handling text but at least it is reliable.