Intrinsic Rowhammer PUFs: Leveraging the Rowhammer effect for improved security

Abstract

Physically Unclonable Functions (PUFs) have become an important and promising hardware primitive for device fingerprinting, device identification, or key storage. Intrinsic PUFs leverage components already found in existing devices, unlike extrinsic silicon PUFs, which are based on customized circuits that involve modification of hardware. In this work, we present a new type of a memory-based intrinsic PUF, which leverages the Rowhammer effect in DRAM modules -the Rowhammer PUF. Our PUF makes use of bit flips, which occur in DRAM cells due to rapid and repeated access of DRAM rows. Prior research has mainly focused on Rowhammer attacks, where the Rowhammer effect is used to illegitimately alter data stored in memory, e.g., to change page table entries or enable privilege escalation attacks. Meanwhile, this is the first work to use the Rowhammer effect in a positive context -to design a novel PUF. We extensively evaluate the Rowhammer PUF using commercial, off-the-shelf devices, not relying on custom hardware or an FPGA-based setup. The evaluation shows that the Rowhammer PUF holds required properties needed for the envisioned security applications, and could be deployed today.

Intrinsic Run-time Row Hammer PUFs: Leveraging the Row Hammer Effect for Run-Time Cryptography and Improved Security

“…This paper extends the work done by Schaller et al [1] by making the following additonal contributions:…”

“…Additionally, we also present and discuss our Row Hammer PUF implementation, in comparison to the implentation presented by Schaller et al [1]. In particular, we introduce an improved run-time accessible implementation of the Row Hammer PUF, which leverages a Linux kernel module, in a similar way to the work of Xiong et al [17], in order to provide access to DRAM characteristics utilised by the Row Hammer PUF.…”

“…However, as proven by the work of Schaller et al [1], which was published in 2017, the row hammer effect can also be used to actually enhance the security of a system, rather than diminish it. This paper extends the work of Schaller et al, demonstrating that the row hammer effect can be utilised to provide run-time accessible cryptographic applications and improved security.…”

“…In order to present the contributions of this paper in a transparent manner, we first list the contributions made by the original work of Schaller et al [1] that this paper extends, and then presents the additional contributions made by this paper.…”

“…However, as recent work has demonstrated, the times needed in order to generate their responses may prohibit their widespread usage. In order to address this issue, the Row Hammer PUF has been proposed by Schaller et al [1], which leverages the row hammer effect in DRAM modules to reduce the retention times of their cells and, therefore, significantly speed up the generation times for the responses of PUFs based on these retention times. In this work, we extend the work of Schaller et al by presenting a run-time accessible implementation of this PUF and further reducing the time required for the generation of its responses.…”