QRYPT allows you to create a send secret messages via QR codes.

Use a friend's Qrypt Key to encode messages. You can then send that message to them, and only they will be able to decipher it.

You can share Qrypt keys via QR code, via email, direct message or even publicly over Twitter.
Save the Qrypt Key with that person's name. From that point on, you can encode secret messages that only that person can decipher and read.
Don't worry if someone gets your Qrypt code. It can only encrypt messages, not decrypt them.

The only person who can decipher and read a QR code message, created using a Qrypt Key, is the person who created that Qrypt key.
Other QR code readers will only see gobbledygook.

*This app uses 2048 bit RSA public-private key encryption technology.