Crypto Notepad is a notepad similar to the default Windows notepad, but, with security built-in. You can password protect your notes with the Advanced Encryption Standard (AES). Don’t let that big word scare you off. Simply download, unzip (portable app), run and then assign a password to the note(s) you create.
It is often necessary to protect important notes in order to prevent them from being accessed by others, but text editors that offer encryption features are sometimes too complex for users who just want a secure Notepad alternative. Crypto Notepad stands out through its relatively simple design, as it looks very similar to the standard Windows Notepad. It offers a few extra features, such as encryption and a customizable UI, but it remains lightweight and very easy to use.
Source: Crypto Notepad