GridTrust PUF Setup

 

The PUF utilized by the GridTrust framework is an SRAM PUF found on the LPC55S69 microprocessor. Our PUF usage utilizes two bare-metal scripts. First, an enrollment script is ran to initialize the PUF and store a chosen counter and AES key value. Second, an operational script is flashed to the memory of the device for deployment of the PUF board.

Source Code

Github link (Note: source code release is being prepared)

Device Utilized

LPCXpresso55S69 Development Board

Software Utilized

MCUXpresso SDK

Setup

The PUF setup first enrolls a desired AES key and a 128-bit counter onto the LPC55S69 microprocessor. These steps are accomplished with the MCUXpresso SDK, available from NXP.

1. Install MCUXpresso
2. Load the enroll project found at github puf/enroll.zip
3. Change the counter and AES key values found in the enroll.c file
   • Found on lines 60 and 63 of enroll.c
   • Note: these values are represented as the same endianess as the values stored in the server’s database.
4. Build the enroll project and run the program on the PUF board one time.
5. Load the encrypt_ctr project found at github puf/encrypt_ctr.zip
6. Build the project and flash the program onto the PUF board
   • Do not run the program as this will increment the counter stored on the board
7. Repeat steps 2-6 for each PUF board.