Whether it’s hiding messages under the stamps on letters or writing in invisible ink, people have always found ingenious ways of using whatever technology they have available to write secret messages. A new project carried out by researchers at Columbia University continues this tradition by using some deep learning technology to embed encrypted messages in otherwise ordinary looking text.
“Fontcode” works by making incredibly subtle modifications to everyday fonts like Times New Roman and Helvetica, embedding coded messages inside them. These changes are so subtle that the average person viewing the text would be incredibly unlikely to notice them. They include such alterations as slightly sharper curves or a minutely thicker stem on a particular letter. Each letter has 52 different variations, which makes it possible to encode both lowercase and capital letters within every letter of the alphabet, along with punctuation marks and numbers, too.
The researchers then trained a deep learning neural network to recognize these letters and to match them back to the coded letters in the secret message. With the right smartphone app and just a short period of time for processing the data, it’s possible to decode a secret message from the document it’s embedded in. Simply aim your device at the text and, as if by magic, the real message can be extracted.
Would such a technique ever be applied in the real world? Almost certainly not in everyday conversations, where the idea of having to send one another false text documents to embed a short hidden message sounds like way too much work. However, that doesn’t mean that this is relegated to being an impractical, albeit impressive, demo. It could certainly have applications in the security field, as well as potentially as an invisible watermark. Heck, you could even use it as a to- secret QR code to link to a web address.
A paper describing the project, titled “FontCode: Embedding Information in Text Documents using Glyph Perturbation,” will be presented later this year at the Special Interest Group on Computer Graphics and Interactive Techniques (SIGGRAPH) 2018 conference.
Someone should probably forward this research on to the James Bond producers before then, though. We can totally imagine Daniel Craig using the “Fontcode” algorithm in the next 007 movie!