Silicon Fingerprint Device Identification

The startup behavior of SRAM forms a unique pattern. This pattern is only available after SRAM power-up and is unique for each chip yet very persistent across a wide range of operating conditions. As some of the bits in the pattern are unstable, the pattern displays some variation i.e. it is fuzzy. An SRAM startup pattern is therefore a fuzzy identifier or a fuzzy ID.

A fuzzy-to-fixed convertor based on SRAM PUF

The fuzzy identifier can be turned into a fixed identifier by matching it with a reference response. The FUZZY ID™ Server software records the initial fuzzy identifier  (e.g. 128 bytes) produced by a chip as a reference. It then extracts a fixed identifier (e.g. 64 bits) from it. This fixed identifier is a stable, collision-free identifier that can be used as a chip ID or serial number.

Later, the chip will produce a new fuzzy identifier which is slightly different due to noise. The FUZZY ID software uses a scalable and efficient algorithm to convert it back to the same fixed identifier.

Note that the exact length of the fuzzy and fixed identifiers depends on the requirements of the application.

Fuzzy ID Use Cases

Invisible Tag

Fuzzy IDs or SRAM PUF measurements recorded during manufacturing of devices can later be used for supply chain audits or counterfeit checks. The FUZZY ID output is like an invisible and tamper-resistant serial number embedded in a chip.

Identification without NVM

Using current technologies, devices without any non-volatile memory cannot store any identifier or any key. FUZZY ID can be used to identify such devices from their SRAM PUF fingerprint.

Operating Conditions

Intrinsic ID’s has characterized SRAM PUF behavior in a wide range of circumstances and can therefore guarantee reliable FUZZY ID operation in the following scenarios:

  • Qualified semiconductor process nodes ranging from 180nm to 14nm
  • Applications include low power, high speed, and high density
  • Temperature range for PUF reading from -50°C to 150°C [-58°F to 300°F]
  • Voltage supply variation tested at +/- 20%
  • Lifetime > 25 years


The endpoint that produces the fuzzy ID simply needs to send uninitialized SRAM contents without any processing. On most processor architectures this requires only a few instructions. Sample code will be provided for common platforms.

The FUZZY ID server needs to do the fuzzy matching among potentially millions of entries and needs to be highly scalable. Intrinsic ID will provide the source code for the matching algorithm as well as reference architecture for a scalable set-up with load balancing.

In addition, Intrinsic ID can provide the following related services:

  • Security consulting and architecture
  • Product support and maintenance
  • Design integration
  • Server-side code and integration

Key Benefits

  • Device identification from chip’s silicon fingerprint
  • Requires only small amount of (non-dedicated) SRAM
  • Very efficient and scalable conversion of a fuzzy ID to a fixed ID 
  • Results in 64+ bit collision-free identifier 
  • Reliable and robust technology 
  • Compatible with QUIDDIKEY and BROADKEY for key management

Target Markets

  • Chip identification
  • Semiconductor manufacturing and supply chain management
  • IP and software protection
  • Supply chain protection and anti-counterfeiting
  • RFID tags
  • Embedded components