Analyzing fingerprints found at the scene of the crime is a classic way to identify a criminal who has accidentally left behind his or her unique signature. But what if there’s another way to use fingerprints—one which could even help a criminal achieve their ill-intentioned goals? In an interesting twist, researchers in China have described a way to use fingerprints to encode secret messages.

Take a look at your fingers and note the continuous lines that occasionally swirl into a spiral. Researchers at Fudan University have developed a sophisticated way to construct digital fingerprints that encode secret messages into these spiral points. Their research was published last week in IEEE Transactions on Image Processing.