  Physically Unclonable Functions (PUFs) are potential security blocks to
generate unique and more secure keys in low-cost cryptographic applications.
Dynamic random-access memory (DRAM) has been proposed as one of the promising
candidates for generating robust keys. Unfortunately, the existing techniques
of generating device signatures from DRAM is very slow, destructive (destroy
the current data), and disruptive to system operation. In this paper, we
propose \textit{precharge} latency-based PUF (PreLatPUF) that exploits DRAM
\textit{precharge} latency variations to generate signatures. The proposed
PreLatPUF is fast, robust, least disruptive, and non-destructive. The silicon
results from commercially available $DDR3$ chips from different manufacturers
show that the proposed key generation technique is at least $ \sim 1,192X$
faster than the existing approaches, while reliably reproducing the key in
extreme operating conditions.
