Markus Guenther Kuhn (born 1971) is a German computer scientist, currently working at the Computer Laboratory, University of Cambridge and a fellow of Wolfson College, Cambridge.
Kuhn's main research interests include computer security, in particular the hardware and signal-processing aspects of it, and distributed systems.
He is known, among other things, for his work on security microcontrollers, compromising emanations, and distance-bounding protocols.
He developed the Stirmark test for digital watermarking schemes, the OTPW one-time password system, and headed the project that extended the X11 misc-fixed fonts to Unicode.
In 1994, as an undergraduate student, he became known for developing several ways to circumvent the VideoCrypt encryption system, most notably the Season7 smartcard emulator.