I recently received a postcard from a designer based in the Netherlands named Amy Suo Wu. It seemed innocuous at first, a simple piece of cardboard with a series of bold graphics on the front and a handwritten address. Peering closer, I noticed a tiny URL directing me to a location on Google maps. When I cut holes into the card as I’d been instructed to by an email from Wu, and then placed the postcard over my screen, a secret message appeared. It was visible through the card’s holes, made from letters on the digital map. This postcard was no ordinary missive at all, but actually what’s known as a Cardan grille—a centuries-old technique for writing secret messages—one that Wu has updated to suit our digital times.
Wu has been researching the potential of analogue forms of secret communication like the Cardan grille and invisible ink for a number of years now, as part of her own artistic practise and for a hacking course that she teaches design students at the Willem de Kooning Academy. “At first, invisible ink and secret writing seemed like a magical and very tactile way to engage students with the difficult subject of online surveillance and the often frustratingly impenetrable complexities,” says Wu.
Her research into the field of analog steganography—the art of hiding messages within a seemingly ordinary piece of communication, and the extraction of their secrets—focuses on developing secure and accessible communication methods in a time of pervasive corporate and governmental spying. This month, Wu’s released the culmination of her research in the form of a chunky, spiral-bound book peppered with illustrations. A Cookbook of Invisible Writing, published with Onomatopee press, contains numerous recipes for secret communication, including nine recipes for invisible ink. As well as being a form of instructional manual, the book contains essays on colonial histories and modern-day applications of surveillance technologies, as well as case studies, puzzles, and a few hidden messages of its own. Together, they attest to the subversive potential of pre-digital spy methods.
“Obsolete analog techniques such as the Cardan grille on paper could be tactically used to subvert surveillance and evade censored contexts precisely because most of our communication is digital,” says Wu. “Paper is not ‘smart’—it doesn’t send information back and forth to servers around the world, and thus it cannot so easily be intercepted by third parties.” Wu cites an example of the relative security of paper as exemplified by a scene in Citizen Four, the documentary film on Edward Snowden, where the journalist Glenn Greenwald resorts to paper and pen to communicate. “In fact, the option of going offline or off-the-grid is becoming increasingly relevant due to our digital vulnerability and unease generated around that reality,” says the artist. “Such sentiments are mirrored by changes in consumer behaviour. One local German publication reported that following the Snowden revelations in 2013, Bandermann and Olympia typewriter manufacturers were experiencing a customer surge.”
Wu locates a radical potential in analog forms, and sees print as taking on a newfound relevance especially in the context of governmental censorship. One of Wu’s essays, for example, recounts time spent in China with the artist-run zine collective Font Fo: “It was fascinating but not surprising to hear them talk about harnessing the tactical nature of printed DIY zines,” says Wu. “Running out of a home-studio in Guangzhou, Fong Fo prints, binds, and distributes its work on paper in a conscious effort to circumvent stringent censorship measures and publish more freely in the government-restricted Chinese media landscape.”
Several of Wu’s own design projects, which are documented in the book, have tapped into the subversive potential of DIY, tactile ephemera, such as her 2017 Thunderclap “walking zine”. For the piece, Wu embedded subversive content into QR codes woven onto fashion accessories. This steganographic design uses unsuspicious fashion accessories to distribute the anarchist writings of a largely forgotten Chinese feminist to passers-by on busy streets. According to Wu, the QR code “has become a ‘habitualized’ mode of information access and as a result its pervasive visual presence inadvertently provides an inconspicuous cover.”
In the tradition of manuals published on secret writing, Wu’s cookbook channels the spirit of accessibility, of easy distribution, and information sharing. An important source of inspiration has been Della Porta’s 1558 popular science book Natural Magic, which was one of the first publications to disperse invisible ink recipes to a wide audience. “In essence, the Cookbook is a hybrid compilation,” says Wu. “It’s my hope that this Cookbook might be able to contribute to the conversation by helping you make small changes and perform acts of resistance at whatever scale, wherever you find yourself to be.”