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Functional Obfuscation of Integrated Circuits

Technology #20170392

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Integrated CircuitAnti-counterfeit
Keshab Parhi, PhD
Professor, Electrical and Computer Engineering
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Sandhya Koteshwara
Electrical and Computer Engineering
Managed By
Kevin Nickels
Technology Licensing Officer 612-625-7289
Patent Protection

US Patent Pending
Key-Based Dynamic Functional Obfuscation of Integrated Circuits Using Sequentially Triggered Mode-Based Design
IEEE Transactions on Information Forensics and Security, Volume: 13, Issue: 1, Jan. 2018

Electronics Counterfeit Protection

Dynamic functional obfuscation is a hardware obfuscation that addresses electronics counterfeiting by programming the key after an integrated circuit is fabricated. Doing so protects intellectual property by preventing black market selling of excess chips (e.g., those overproduced and sold by a foundry) for which the foundry does not have access to the key. The approach, based on dynamic obfuscation inspired by researching hardware Trojans, has several advantages, such as stronger security, smaller key size requirements and greatly increased time to attack. The technology includes a trigger generator configured to generate a non-periodic trigger output and a multiplexer configured to output a valid control signal and an obfuscated control signal in response to a key value input. The obfuscated control signal is selectively set to one of a valid control signal and an invalid control signal based on the non-periodic trigger output. In addition, a hybrid obfuscation scheme that combines concepts from dynamic and fixed obfuscation offers even more advantages and lower overheads.

Stronger Obfuscation

Current hardware obfuscation techniques suffer from several shortcomings, leaving them vulnerable to attack. In addition, some current methods are difficult to design and implement while others cause overheads in terms of area, power or by increasing timing requirements. Existing schemes also face key problems, because someone with the device can still quickly find the key. This new approach keeps the key values secret during the manufacturing process, so any attempt by unauthorized parties to overproduce chips or pirate designs is thwarted. In this dynamic obfuscation approach, the circuit behaves incorrectly sometimes (unlike fixed obfuscation, where an incorrect key always results in incorrect outputs). This technique differs from existing fixed obfuscation schemes as the obfuscating signals change over time, resulting in inconsistent circuit behavior upon input of incorrect key: the chip sometimes operates correctly and sometimes fails. The advantage is stronger obfuscation by increasing the time complexity of deciphering the correct key using brute-force attack, even with shorter keys. Moreover, the dynamic nature of these circuits also makes them resistant to reverse engineering and SAT solver based attacks.


  • Dynamic functional obfuscation
  • Obfuscating signals change over time, resulting in inconsistent circuit behavior upon input of incorrect key: the chip sometimes operates correctly and sometimes fails
  • Hybrid obfuscation scheme combines dynamic and fixed obfuscation concepts
  • Addresses electronics counterfeiting
  • Programs keys after integrated circuit fabrication; foundries do not have access to keys
  • Comprised of a trigger generator and a multiplexer
  • Increases time to attack by many orders of magnitude
  • Stronger obfuscation
  • Stronger security
  • Smaller key size
  • Lower overheads


  • Obfuscating signals
  • Integrated circuit fabrication

Phase of Development - Prototype developed. Non-exclusive license available for technology patent.