steganographic technique<\/a>, meaning it hides secret information in plain sight such that only its intended recipient knows where to look for it and how to extract it. FontCode can be applied to hundreds of common fonts, like Helvetica or Times New Roman, and works in word processors like Microsoft Word. Data encoded with FontCode can also endure across any image-preserving digital format, like PDF or PNG. The secret data won't persist after, say, copy and pasting FontCode text between text editors.<\/p>\nThe most significant format conversion FontCode messages can transcend, though, is digital to physical and back.<\/p>\n
\u201cMany modern steganographic techniques are always in digital files, but you can argue that the world is much larger than just digital formats,\u201d says Changxi Zheng, a computer scientist at Columbia University who worked on the FontCode research. \u201cSo the question was how can we design a common physical object to convey digital information without compromising its existing functionality. I call it a hyperlink between a physical object and digital information.\u201d<\/p>\n
The text perturbations FontCode uses to embed a message involve slightly changing curvatures, widths, and heights\u2014but crucially it's all imperceptible to the naked eye. You can intuit that some letters, like capital "I"s or "J"s, don't have a lot of complexity in which to hide subtle variations. But lowercase "a"s and "g"s, for example, have lots of edges and curves that can be elongated or shortened and bulked up or paired down.<\/p>\n
The only easy way to extract the hidden information in all those tiny tweaks is with the research teams' decoding algorithm. A recipient of a FontCode message could use their smartphone to take a picture of text manipulated with FontCode, then run the photo through a dedicated mobile app that decrypts the code to pull out the hidden message. It would also be possible to set up decoding schemes that use a webcam, a scanner, or any other image digitization method. You can see how it works in the video below.<\/p>\n
![](\"https:\/\/media.wired.com\/photos\/5afe1cc38154d3076bfdd582\/master\/pass\/Hidden-Messages.png\"\/)
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