Protect the notes in your contact book with a password. Once you have entered a password all notes that you add or modify will be protected with this password. You can now freely add passwords, login names and credit card information in the notes of your contact book without worrying that your notes can be disclosed (e.g. by applications that request access to your contact book, hackers, etc).
The Locker application protects your notes by using powerful encryption algorithms and allows you to easily protect any unprotected notes, change the password of protected notes, add protection to all of your notes at once or remove the protection of your notes when you dont need them anymore.