WinCrypt
offers password based file encryption using the Twofish symmetric key block cipher.(It let's you put passwords on files, so only someone with the password can read them.)
Download for Windows
(.NET 4.0 or better)
WinCrypt
Free is open source
software. This means you can be sure that the software includes no back-doors, or other trickery that might compromise the encryption of your data.
You can view, download and contribute to the WinCrypt source on GitHub.