Secretbook is an amazing extension or addon for your chrome browser that lets you send secret messages on Facebook by hiding them in Photos. This technique of hiding text in Photos is called ‘steganography’ and Secretbook uses this technique to to share messages on Facebook discreetly.
This chrome extension is developed by Owen Campbell-Moore as a research project in Oxford University.According to Moore, he studied image compression methods of Facebook and developed a way to add text to photos that cannot be destroyed once uploaded to Facebook.
Using the Secretbook extension is quite simple, just select an image, type your message and secure it with Password and share it on Facebook. Friends can then press Ctrl+Alt+A and enter the password (if you’ve told them what it is) to read your secret message. The text limit is set by the size of your image.
Download : Secretbook addon for Chrome