Pim T. Tuyls

Memory Leakage-Resilient Encryption Based on Physically Unclonable Functions

Physical attacks on cryptographic implementations and devices have become crucial. In this context a recent line of research on a new class of side-channel attacks, called memory attacks , has received increasingly more attention. These attacks allow an adversary to measure a significant fraction of secret key bits directly from memory, independent of any computational side-channels. n nPhysically Unclonable Functions (PUFs) represent a promising new technology that allows to store secrets in a tamper-evident and unclonable manner. PUFs enjoy their security from physical structures at submicron level and are very useful primitives to protect against memory attacks. n nIn this paper we aim at making the first step towards combining and binding algorithmic properties of cryptographic schemes with physical structure of the underlying hardware by means of PUFs. We introduce a new cryptographic primitive based on PUFs, which we call PUF-PRFs. These primitives can be used as a source of randomness like pseudorandom functions (PRFs). We construct a block cipher based on PUF-PRFs that allows simultaneous protection against algorithmic and physical attackers, in particular against memory attacks. While PUF-PRFs in general differ in some aspects from traditional PRFs, we show a concrete instantiation based on established SRAM technology that closes these gaps.

Hardware Intrinsic Security from Physically Unclonable Functions

Counterfeiting of goods in general and of electronic goods in particular is a growing concern with a huge impact on the global economy, the society, and the security of its critical infrastructure. Various examples are known where companies suffer from economic and brand damage due to competition with counterfeit goods. In some cases the use of counterfeit components has even led to tragic accidents in which lives were lost. It has also recently become clear that counterfeit products can penetrate the critical and security infrastructure of our modern societies and hence cause a threat to national security.

Process Variations for Security: PUFs

Process variations in deep-submicron technology lead usually to undesired effects. Manufacturers of ICs try to remove those as much as possible in order to be sure that all their devices function in the same and expected way. In this chapter, we show how process variations which make a device unique can be used to provide new, cheap and enhanced security functionality to the device. We identify physical unclonable functions (PUFs) based on process variations that are present on an IC and explain how they can be used to provide enhanced security features for the IC.