DRAM based Intrinsic Physical Unclonable Functions for System Level Security

Physical Unclonable Functions (PUF) are the result of random uncontrollable variables in the manufacturing process. A PUF can be used as a source of random but reliable data for applications such as generating chip identification and encryption keys. Among various types of PUFs, an intrinsic PUF is the result of a preexisting manufacturing process, does not require any additional circuitry, and is cost effective. In this paper, we introduce an intrinsic PUF based on dynamic random access memories (DRAM). DRAM PUFs can be used in low cost identification applications and also have several advantages over other PUFs such as large input patterns. The DRAM PUF relies on the fact that the capacitor in the DRAM initializes to random values at startup. We demonstrate real DRAM PUFs and describe an experimental setup to test different operating conditions on three DRAMs to achieve the highest reliable results. Finally, we select the most stable bits to use as chip ID using our enrollment algorithm.