Embedded systems are increasingly ubiquitous. Many of them have security requirements such as smart cards, mobile phones, and internet connected appliances. It can be a challenge to fulfill security requirements due to the constrained nature of embedded devices. This security challenge is worsened by the possibility of implementation attacks. Despite well formulated cryptosystems being used, the underlying hardware can often undermine any security proven on paper. If a secret key is at play, an adversary has a chance of revealing it by simply looking at the power variation. Additionally, an adversary can tamper with an embedded system's environment to get it to skip a security check or generate side channel information.
Any adversary with physical access to an embedded system can conduct such implementation attacks. It is the focus of this work to explore different countermeasures against both side channel and fault attacks. A new countermeasure call Intra-instruction Redundancy, based on bit-slicing, or N-bit SIMD processing, is proposed. Another challenge with implementing countermeasures against implementation attacks, is that they need to be able to be combined. Most proposed side channel countermeasures do not prevent fault injection and vice versa. Combining them is non-trivial as demonstrated with a combined implementation attack. / Master of Science / Consider a mechanical dial lock that must be opened without knowing the correct combination. One technique is to use a stethoscope to closely listen to the internal mechanical sounds and try to pick out any biases in order to figure out the correct combination without having to go through an exhaustive search. This is what a side channel is.
Embedded systems do not have mechanical sound side channels like mechanical locks but they do leak information through power consumption. This is the basis for power analysis attacks on embedded systems. By observing power, secret information from an embedded system can be revealed despite any cryptographic protections implemented. Another side channel is the behavior of the processor when it is physically tampered with, specifically known as a fault attack. It is important that embedded systems are able to detect when they are tampered with and respond accordingly to protect sensitive information.
Side channel and fault attack countermeasures are methods for embedded systems to prevent such attacks. This work presents a new state of the art fault attack countermeasure and a framework for combining the countermeasure with existing side channel countermeasures. It is nontrivial to combine countermeasures as there is a potential for combined attacks which this work shows as well.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/78685 |
| Date | 09 August 2017 |
| Creators | Patrick, Conor Persson |
| Contributors | Electrical and Computer Engineering, Schaumont, Patrick R., Nazhandali, Leyla, Gerdes, Ryan M. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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