Oblivious Transfer Based on Physical Unclonable Functions

Ulrich Rührmair, Marten van Dijk

Harishma Boyapally, Chandan Kumar, Debdeep Mukhopadhyay

Oblivious Transfer (OT) protocol is nowadays recognised as a generic primitive for all cryptographic protocols since it is one of the strongest primitives for secure multiparty computation (MPC). To design hardware-assisted OT protocols, Physically Unclonable Functions (PUFs) have been thoroughly studied in the literature. PUF-based OT protocols, however, necessitate the physical transfer of PUF devices, rendering them inappropriate in situations where the physical transfer of devices is not secure. Additionally, two-party secure computation protocols, in general, are performed between two distrusting parties. Yet, the PUF-based OT protocols require the PUF receiver to trust the PUF sender to behave honestly. Recent works have considered malicious PUF models resulting in more complex protocols. To avoid these drawbacks, we in this work rely on the concept of Physically Related Functions (PReFs), a pair of PUF devices that allow two PUF devices to generate similar responses over a "related" input set. XOR composition of PReFs, also called XOR_PReF, is an improved construction that eliminates the need for any trusted party and generates a "related" input set securely and independently. With the help of this new primitive, we propose 1-out-of-2 OT protocols using XOR_PReF in semi-honest as well as malicious settings keeping the protocol secure even after switching the roles of OT-sender and OT-receiver. Our protocols can be integrated into hardware-assisted MPC protocols and provide a safe and valuable solution for all OT-based techniques, notably Private Set Intersection (PSI), Private Information Retrieval (PIR), and Password Authenticated Key Exchange (PAKE).

Moni Naor, Benny Pinkas B

Harishma Boyapally, Sikhar Patranabis, Debdeep Mukhopadhyay

Commitment schemes are one of the basic building blocks to construct secure protocols for multi party computation. Many recent works are exploring hardware primitives like physically unclonable functions to build keyless cryptographic protocols, with minimal assumptions. The asymmetric nature and non-invertibility property of PUFs are widely exploited to build oblivious transfer protocols that are extended to build bit-commitment schemes. However, these schemes require the physical transfer of the PUF device between the interacting parties. In this work, we introduce a new class of hardware-based primitives called physically related functions that enable hardware circuits to securely communicate with each other over insecure channels. We propose a bit-commitment protocol based on this hardware primitive without needing any physical transfer. Our scheme is statistically hiding and computationally binding, requiring only one round of communication while being practically deployable. We explore the security properties of physically related functions, under which we prove the security of our scheme. We experimentally show that it is impossible to break the security of the scheme with more than negligible probability.

Alexander Frolov

Mihir Bellare Y, Silvio M. Micali