Extracting a Secure Key from the Intrinsic Silicon Fingerprint

SRAM Physical Unclonable Functions or SRAM PUF use the behavior of standard SRAM memory, available in any digital chip, to differentiate chips from each other. They are virtually impossible to duplicate, clone or predict. This makes them very suitable for applications such as secure key generation and storage, device authentication, flexible key provisioning and chip asset management.

Due to deep sub-micron process variations in the production process, every transistor in SRAM cells has slightly random electric properties. This randomness is expressed in the startup values of ‘uninitialized’ SRAM memory. These values form a unique chip fingerprint, called the SRAM PUF response.

The SRAM PUF response is a noisy fingerprint, and turning it into a high-quality and secure key vault requires further processing. This is done with the Intrinsic ID IP.  Using our IP it is possible to reconstruct exactly the same cryptographic key every time and under all (environmental) circumstances.

This way of deriving a key from the SRAM properties has great security advantages compared to traditional key storage in non-volatile memory. Because the key is not permanently stored, it is not present when the device is not active (no key at rest) and hence cannot be found by an attacker who is opening up the device and compromising all the memory contents.

Intrinsic ID’s SRAM PUF technology has been tested under extreme conditions of temperature, ageing and usage and has been fine-tuned over a decade to ensure that it works reliably over time in every imaginable scenario for all major IC technologies.

Key Benefits of SRAM PUF technology:

  • Device-unique inclinable fingerprint
  • Leverages entropy of mfg. process
  • No key material programmed