Now, RFID security can be enhanced, and made "unclonable" by linking it inseparably to a Physical Unclonable Function (PUF) – a solution that's practically impossible to model, copy, or control.

Radio frequency identification (RFID), a technology that uses radio signals for object identification, is today one of the most popular anti-counterfeiting solutions. RFID-tags, with their small microchips, help verify a product's authenticity to detect and prevent counterfeiting. However, privacy and security concerns – particularly the technology's ability to fend off attacks, like the cloning of the tag – often inhibit its effectiveness. And privacy and security cryptographic defenses are too hardware-expensive to incorporate into low-cost RFID tags.

To enhance RFID security, RFID-tag can be made unclonable by linking it inseparably to a Physical Unclonable Function (PUF). By exploiting the physical characteristics of the silicon and the inherent integrated circuit (IC) manufacturing process variations, PUFs can uniquely characterize each and every silicon chip. Since it is practically impossible to model, copy, or control the IC manufacturing process variations, PUFs not only make these chips unique, but also practically unclonable. Thus, PUFs provide a secure, robust, low cost mechanism to authenticate silicon chips. This makes PUFs attractive for RFID ICs where cost and security are the key requirements.

According to a paper co-authored by Srinivas Devadas, who pioneered the technology at the Massachusetts Institute of Technology…

Physical Unclonable Functions (PUFs) are innovative primitives [that] derive secrets from complex physical characteristics of [integrated circuits or] ICs rather than storing the secrets in digital memory. For example, a volatile secret can be generated from the random delay characteristics of wires and transistors. Because the PUF taps into the random variation during an IC fabrication process, the secret is extremely difficult to predict or extract.

PUFs significantly increase physical security by generating volatile secrets that only exist in a digital form when a chip is powered on and running. This immediately requires the adversary to mount an attack while the IC is running and using the secret, a significantly harder proposition than discovering non-volatile keys; an invasive attack must accurately measure PUF delays without changing the delays or discover volatile keys in registers without cutting power or tamper-sensing wires that clear out the registers.

When equipped with such a system, RFID can better prevent counterfeiting of intellectual property. And this is amply demonstrated by a company that has incorporated the PUF concept into its anti-counterfeiting technologies:

Brand Sentry's version of this powerful and innovative new solution, productized in Silicon Valley and perfected for use in a remarkable new class of low-cost, highly secure RFIDs, taps the "physical DNA" intrinsic to silicon crystals at the atomic level to generate effectively unclonable secret keys that can be extracted electronically from chips attached to branded products. Its approach results in a counterfeit detection and prevention tools that's:

• Unclonable - Cannot be copied or duplicated
• Low-cost - Cost-effective deployments
• Low-power - Can be used with hand-held readers
• Small and flexible - Can be integrated into many form factors
• Robust - Works in harsh operating environments 

PUF-based secret keys are never burned into the chips themselves, but are intrinsic to the physical characteristics of the silicon itself. Even the chips' manufacturer does not know these secrets and cannot duplicate the "physical DNA" of any single chip.  They exist only when power is applied and can only be generated, read, and authenticated by Brand Sentry-authorized systems.

PUF technology not only enhances RFID security but could very well take brand protection into a whole new level.