Tamper resistant cryptographic processing with physically unclonable functions

Tamper resistant cryptographic key generation and storage is a critical function for any secure cryptosystem. Such a system must provide protection from attackers who attempt to read a key stored within the system to gain access to the protected information. A system that derives the key from a Physically Unclonable Function (PUF) measurement rather than storing the key electronically has greatly improved security since key storage is vulnerable to attacks. Once a key has been generated, the key security problem becomes one of preventing adversaries from obtaining it. The act of attempting to obtain a stored key is called tampering and any steps taken to physically protect the key from an adversary are called anti-tamper (AT). Two new PUPs are introduced; one that uses a Micro-Electromechanical Systems (MEMS) capacitor and another that combines a coated PUP and a silicon delay PUP. Pressure is used as an AT protection mechanism by the MEMS PUF and coated capacitors are used by the coated silicon PUP to prevent probing by an adversary. It is shown that the coated silicon PUP can function as a random number generator (RNG) by converting the silicon delay circuits into ring oscillators. To verify the strength of the RNG, it is implemented in a Field Programmable Gate Array (FPGA) and the measured output tested. These results show that the design outperforms other PUP-based RNGs. The RNG is smaller and uses simpler post processing logic than others proposed in literature.