Sam Kerr

Authentication and key management for Advanced Metering Infrastructures utilizing physically unclonable functions

Conventional utility meters are increasingly being replaced with smart meters as smart meter based AMIs (Advanced Metering Infrastructures) provide many benefits over conventional power infrastrucutures. However, security issues pertaining to the data transmission between smart meters and utility servers have been a major concern. With large scale AMI deployments, addressing these issues is challenging. In particular, as data travels through several networks, secure end-to-end communication based on strong authentication mechanisms and a robust and scalable key management schemes are crucial for assuring the confidentiality and the integrity of this data. In this paper, we propose an approach based on PUF (physically unclonable function) technology for providing strong hardware based authentication of smart meters and efficient key management to assure the confidentiality and integrity of messages exchanged between smart meters and the utility. Our approach does not require modifications to the existing smart meter communication. We have developed a proof-of-concept implementation of the proposed approach which is also briefly discussed in the paper.

Marlin: A Fine Grained Randomization Approach to Defend against ROP Attacks

Code-reuse attacks, such as return-oriented programming (ROP), bypass defenses against code injection by repurposing existing executable code toward a malicious end. A common feature of these attacks is the reliance on the knowledge of the layout of the executable code. We propose a fine grained randomization based approach that modifies the layout of executable code and hinders code-reuse attack. Our solution, Marlin, randomizes the internal structure of the executable code, thereby denying the attacker the necessary a priori knowledge of instruction addresses for constructing the desired exploit payload. Our approach can be applied to any ELF binary and every execution of this binary uses a different randomization. Our work shows that such an approach is feasible and significantly increases the level of security against code-reuse based attacks.

PEAR: a hardware based protocol authentication system

As users have to manage an increasing number of accounts, they have to balance password security and password usability. As such, many users use insecure passwords resulting in their accounts and data being vulnerable to unauthorized accesses. In this paper, we present Physically Enhanced Authentication Ring, or PEAR, a system that alleviates this problem. We leverage Physically Unclonable Functions (PUF) to create unclonable hardware devices, which users use to authenticate. Using a hardware device, our system uses zero-knowledge proofs, which provide better security than traditional passwords, yet users must only enter a simple PIN. As such, our system is very usable and imposes little to no burden on end users and service providers. We present transaction levels on top of PEAR of as an extension and then discuss some other work that could be done in the future.

Enforcing physically restricted access control for remote data

In a distributed computing environment, remote devices must often be granted access to sensitive information. In such settings, it is desirable to restrict access only to known, trusted devices. While approaches based on public key infrastructure and trusted hardware can be used in many cases, there are settings for which these solutions are not practical. In this work, we define physically restricted access control to reflect the practice of binding access to devices based on their intrinsic properties. Our approach is based on the application of physically unclonable functions. We define and formally analyze protocols enforcing this policy, and present experimental results observed from developing a prototype implementation. Our results show that non-deterministic physical properties of devices can be used as a reliable authentication and access control factor.

PUF ROKs: a hardware approach to read-once keys

Cryptographers have proposed the notion of read-once keys (ROKs) as a beneficial tool for a number of applications, such as delegation of authority. The premise of ROKs is that the key is destroyed by the process of reading it, thus preventing subsequent accesses. While the idea and the applications are well-understood, the consensus among cryptographers is that ROKs cannot be produced by algorithmic processes alone. Rather, a trusted hardware mechanism is needed to support the destruction of the key. In this work, we propose one such approach for using a hardware design to generate ROKs. Our approach is an application of physically unclonable functions (PUFs). PUFs use the intrinsic differences in hardware behavior to produce a random function that is unique to that hardware instance. Our design consists of incorporating the PUF in a feedback loop to make reading the key multiple times physically impossible.

Marlin: making it harder to fish for gadgets

Code-reuse attacks, including return-oriented programming (ROP) and jump-oriented programming, bypass defenses against code injection by repurposing existing executable code in application binaries and shared libraries toward a malicious end. A common feature of these attacks is the reliance on the knowledge of the layout of the executable code. We propose a fine grained randomization based approach that modifies the layout of executable code and hinders code-reuse attack. Our solution consists solely of a modified dynamic loader that randomizes the internal structure of the executable code, thereby denying the attacker the necessary apriori knowledge for constructing the desired sequence of gadgets. Our approach has the advantage that it can be applied to any ELF binary and every execution of this binary uses a different randomization. We describe the initial implementation of Marlin, a customized loader for randomization of executable code. Our work shows that such an approach is feasible and significantly increases the level of security against code-reuse attacks.

PUF ROKs: generating read-once keys from physically unclonable functions

Cryptographers have proposed the notion of read-once keys (ROKs) as a beneficial tool for a number of applications, such as delegation of authority. The premise of ROKs is that the key is destroyed by the process of reading it, thus preventing subsequent accesses. While the idea and the applications are well-understood, the consensus among cryptographers is that ROKs cannot be produced by algorithmic processes alone. Rather, a trusted hardware mechanism is needed to support the destruction of the key. In this work, we propose one such approach for using a hardware design to generate ROKs. Our approach is an application of physically unclonable functions (PUFs). PUFs use the intrinsic differences in hardware behavior to produce a random function that is unique to that hardware instance. Our design consists of incorporating the PUF in a feedback loop to make reading the key multiple times physically impossible.