If you’re grasping for the deeper meaning of an essay or article, consider the possibility that it may not be in the words themselves, but hidden in the shape of the letters. It really could be the case, now that researchers from Columbia University have developed a method called FontCode, which plants data in text through tiny changes in how the letters are shaped.
The method is a steganographic technique[1], 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.
The most significant format conversion FontCode messages can transcend, though, is digital to physical and back.
“Many modern steganographic techniques are always in digital files, but you can argue that the world is much larger than just digital formats,” says Changxi Zheng, a computer scientist at Columbia University who worked on the FontCode research. “So 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.”
Invisible Ink
The text perturbations FontCode uses to embed a message involve slightly changing curvatures, widths, and heights—but 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