WARF: P140095US01

Encrypting Intellectual Property Cores


Parameswaran Ramanathan, Kewal Saluja, Spencer Millican

The Wisconsin Alumni Research Foundation (WARF) is seeking commercial partners interested in developing a method for providing useful descriptions of integrated circuits while concealing their underlying design.
OVERVIEWSystem-on-Chip (SoC) is a technique for designing complex integrated circuits using circuit ‘building blocks’ developed by different companies. Electronic files describing each building block are combined and assembled to produce the final product. These building blocks are known as intellectual property (IP) cores, reflecting the fact that their underlying design is sold as opposed to an actual integrated circuit. The ability to license IP cores makes the design of complex circuit elements more efficient and helps share costs among manufacturers.

An IP core can be described in an electronically readable schematic that outlines each component (e.g., logic gates, interconnections and functional descriptions of inputs/outputs). The sale of an IP core may include this entire functional specification, a so-called “soft” core. In contrast, it also is possible to sell a description of an IP core that provides the basic layout but not circuit-level information. This “hard” core allows fabrication of the IP core but hides the circuit design to prevent copying or modification.

The hard core license forms the core of IP vendors’ business but it has a major drawback. Namely, because the details are hidden, it is not possible to simulate the IP core with other building block circuits. The ability to simulate is critical for integrating other circuit elements and identifying component faults.
THE INVENTIONUW–Madison researchers have developed a method for encrypting the functional descriptions of IP cores. The encrypted descriptions allow simulation but still obscure the design and operation of the underlying circuit. This provides more flexible testing capabilities while protecting intellectual property.

First, an encryptor receives a description file of the circuit. The encryptor then outputs a description of the underlying IP core in which the nodes or gates of the circuit are replaced with generic placeholder nodes. These placeholders are given encrypted multivalued truth-tables that permit simulation but effectively disguise their function. For example, multiple alias values may hide the logic of the node, or the truth-table may include erroneous entries. The effect is to render the function of the node symbols practically unintelligible.
  • Encrypting digital circuit description files
  • Preserves the confidentiality of circuit designs
  • Allows end user to perform simulations
  • System works with a large variety of basic circuit building blocks.
  • Provides a standard schematic representation
  • Simulation is extremely rapid and does not require complex decryption steps.
STAGE OF DEVELOPMENTThe encryption method was used on a test system and performed fault simulation using the most common fault model (single stuck-at-fault). Researchers also tested how long it would take to decrypt the circuit and found that it would be very computation heavy and time consuming.

The development of this technology was supported by WARF Accelerator. WARF Accelerator selects WARF's most commercially promising technologies and provides expert assistance and funding to enable achievement of commercially significant milestones. WARF believes that these technologies are especially attractive opportunities for licensing.
Contact Information
For current licensing status, please contact Emily Bauer at or 608-960-9842.
The WARF Advantage

Since its founding in 1925 as the patenting and licensing organization for the University of Wisconsin-Madison, WARF has been working with business and industry to transform university research into products that benefit society. WARF intellectual property managers and licensing staff members are leaders in the field of university-based technology transfer. They are familiar with the intricacies of patenting, have worked with researchers in relevant disciplines, understand industries and markets, and have negotiated innovative licensing strategies to meet the individual needs of business clients.