Physically Unclonable Functions for Fully Fabricated Printed Circuit Boards used in Identification, Authentication, and Cryptographic Key Derivation

Technology #17648

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Michael Geis
Lincoln Laboratory, MIT
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Joshua Kramer
Lincoln Laboratory, MIT
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Karen Gettings
Lincoln Laboratory, MIT
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Marc Burke
Lincoln Laboratory, MIT
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Mankuan Vai
Lincoln Laboratory, MIT
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Theordore Lyszczarz
Lincoln Laboratory, MIT
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Jack Turner
MIT Technology Licensing Officer
Patent Protection

Phosphor-Loaded Waveguide

PCT Patent Application Filed
Full-Wave Analysis and Design of Dielectric-Loaded Waveguide Filters Using a State-Space Integral-Equation Method
EE Transactions on Microwave Theory and Techniques , 57 (1): 109-20, Jan. 9, 2009
Helper-less physically unclonable functions and chip authentication
2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) , 14448207: 8193-7, May 4, 2014


  • Electronic systems needing to incorporate unclonable identification devices for authentication and cryptographic key derivation

Problem Addressed

Many electronic systems use security systems with digital identification for authentication and key derivation. One system security method uses an optical physical unclonable function (PUF), implemented on a printed circuit board. PUFs are constructed from light emitting diodes (LEDs) and an image sensor affixed to the PCB, which is then coated with a thin polymer planar waveguide. The system is designed to create a unique key value from the sensor image. Invasive attempts damage the polymer coating, thus destroying the PUF value. However, current invasive methods can place small enough bounds on the original PUF value from a damaged sensor image that the initial value can be deduced.


The invention provides a method for manufacturing a waveguide which increases the image distortion between the original and damaged image. This significantly increases the difficulty in deducing the initial PUF value from a damaged image. The technology employs a novel two-color phosphor-loaded waveguide technology. When an invasive attempt is made on the system, not only is the image distorted, but color sensitive phosphor is also activated causing a color change in the system. The device can be applied to systems after full fabrication, allowing the security systems of manufactured electronics to be upgraded.  


  • Includes optical effects for improved security and hacker detection
  • Increases image distortion for heightened protection of PUF value from hackers
  • Applicable to fully fabricated systems needing security system upgrades