Physical Unclonable Function


No two silicon chips, even with the same design, technology and fabrication process, are created alike. In the manufacturing process, there are unavoidable and uncontrollable variations at a molecular scale that make each silicon chip unique. With the silicon Physical Unclonable Function (PUF) technology invented by Prof. Srini Devadas and his team at MIT, these semiconductor manufacturing process variations can be used as silicon biometrics to uniquely identify each chip.

At its core, PUFs are tiny electrical circuits extremely sensitive to these minute variations that can be embedded in the chip to extract its unique characteristics. Verayo has developed the technology to probe, interrogate and collect a set of parameters from each PUF circuit to characterize the chip. Since these manufacturing process variations are unpredictable, permanent and impossible to clone, each PUF makes the chip "unclonable" and the parameters become "secrets" for various security applications.

Verayo's technology uses a challenge and response protocol to extract these secrets. Each PUF responds differently to the same challenge based on the "uniqueness" of the chip, its output is affected by the manufacturing variations.

These challenges and responses have the following characteristics:

  • Unique to each chip
  • Consistent across life span, environmental conditions
  • Different ICs have different responses to same challenge

PUF challenge response pairs are used as the secrets to enable two basic functions in a broad range of security applications:

  • Secure authentication of ICs - ASICs, FPGAs
  • Secret key generation for cryptographic applications

Four patents related to the silicon PUF technology were made available from MIT exclusively to Verayo when the company was founded. Since then, ten more have been granted directly to Verayo and eight are pending.

14 patents granted
8 patents pending

PUF Applications

PUF Chip Authentication

A random challenge is generated and an expected response is calculated based on the PUF characteristics. Each random challenge has a unique response. Only an authentic IC can produce a correct response for a challenge.

Response = PUF (challenge, physical silicon)

Using the PUF parameters securely extracted during manufacturing, the same challenge is sent to the chip and, based on the response, it is deemed authentic.

No need for stored keys

PUF authentication is low-cost and simple since it doesn't require crypto, keys or any special fabrication/marking steps. Verayo provides online and offline authentication, securely implemented in the Verayo Authentication Network (VAN) or locally, depending on the client's need.

PUF Key Generation

PUF technology can be used to generate volatile keys from the silicon at very small technology nodes for applications where there is no secure memory.

PUF key generation and provisioning is highly secure and can be integrated into any ASIC and FPGA to establish trust between machines. There is no need for trusted programming and it can be used for cryptographic applications (AES, RSA, HMAC...)

PUF Advantages

PUF technology is elevating the security of semiconductor ICs and IC based systems:

- Since it is effectively impossible to clone PUF based ICs, PUF technology provides a reliable and secure way to authenticate PUF-based ICs and systems.

- Unlike conventional security solutions, PUFs do not store secret keys for cryptographic operations. PUFs dynamically generate unique and volatile secrets for each IC.



Verayo chip has a huge opportunity in India

Interview of Datta Nadkarni, CMO | Verayo with Sachin Jagdale

Our Publications


A Noise Bifurcation Architecture for Linear Additive Physical Functions

Meng-Day (Mandel) Yu, David M'Raihi, I. Verbauwhede, Srinivas Devadas


Performance Metrics and Emperical Results of a PUF Cryptographic Key

Meng-Day (Mandel) Yu, Richard Sowell, Alok Singh, David M'Raihi, Srinivas Devadas


Lightweight and Secure PUF Key Storage Using Limits of Machine Learning

Meng-Day (Mandel) Yu, David M'Raihi, Richard Sowell, Srinivas Devadas


Recombination of Physical Unclonable Functions

Meng-Day (Mandel) Yu, Srinivas Devadas


Design and Implementation of PUF-Based "Unclonable" RFID ICs for Anti-Counterfeiting and Security Applications

Srinivas Devadas, Edward Suh, Sid Paral, Richard Sowell, Tom Ziola, Vivek Khandelwal

Our Researchers

Our researchers have authored and co-authored numerous papers and patents. To learn more:
Meng-Day (Mandel) Yu
Richard Sowell
Srinivas Devadas