Lightweight symmetric cryptography

Mikhalev, Vasily

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URL:	https://madoc.bib.uni-mannheim.de/50318
URN:	urn:nbn:de:bsz:180-madoc-503181
Dokumenttyp:	Dissertation
Erscheinungsjahr:	2018
Ort der Veröffentlichung:	Mannheim
Hochschule:	Universität Mannheim
Gutachter:	Armknecht, Frederik
Datum der mündl. Prüfung:	11 April 2019
Sprache der Veröffentlichung:	Englisch
Einrichtung:	Fakultät für Wirtschaftsinformatik und Wirtschaftsmathematik > Kryptographie (Juniorprofessur) (Armknecht 2010-2015)
Fachgebiet:	004 Informatik
Normierte Schlagwörter (SWD):	Kryptologie , Internet der Dinge , Stromchiffre , Authentifikation
Freie Schlagwörter (Englisch):	Cryptography , Internet of Things Stream Ciphers , Authentification
Abstract:	The Internet of Things is one of the principal trends in information technology nowadays. The main idea behind this concept is that devices communicate autonomously with each other over the Internet. Some of these devices have extremely limited resources, such as power and energy, available time for computations, amount of silicon to produce the chip, computational power, etc. Classical cryptographic primitives are often infeasible for such constrained devices. The goal of lightweight cryptography is to introduce cryptographic solutions with reduced resource consumption, but with a sufficient security level. Although this research area was of great interest to academia during the last years and a large number of proposals for lightweight cryptographic primitives have been introduced, almost none of them are used in real-word. Probably one of the reasons is that, for academia, lightweight usually meant to design cryptographic primitives such that they require minimal resources among all existing solutions. This exciting research problem became an important driver which allowed the academic community to better understand many cryptographic design concepts and to develop new attacks. However, this criterion does not seem to be the most important one for industry, where lightweight may be considered as "rightweight". In other words, a given cryptographic solution just has to fit the constraints of the specific use cases rather than to be the smallest. Unfortunately, academic researchers tended to neglect vital properties of the particular types of devices, into which they intended to apply their primitives. That is, often solutions were proposed where the usage of some resources was reduced to a minimum. However, this was achieved by introducing new costs which were not appropriately taken into account or in such a way that the reduction of costs also led to a decrease in the security level. Hence, there is a clear gap between academia and industry in understanding what lightweight cryptography is. In this work, we are trying to fill some of these gaps. We carefully investigate a broad number of existing lightweight cryptographic primitives proposed by academia including authentication protocols, stream ciphers, and block ciphers and evaluate their applicability for real-world scenarios. We then look at how individual components of design of the primitives influence their cost and summarize the steps to be taken into account when designing primitives for concrete cost optimization, more precisely - for low energy consumption. Next, we propose new implementation techniques for existing designs making them more efficient or smaller in hardware without the necessity to pay any additional costs. After that, we introduce a new stream cipher design philosophy which enables secure stream ciphers with smaller area size than ever before and, at the same time, considerably higher throughput compared to any other encryption schemes of similar hardware cost. To demonstrate the feasibility of our findings we propose two ciphers with the smallest area size so far, namely Sprout and Plantlet, and the most energy efficient encryption scheme called Trivium-2. Finally, this thesis solves a concrete industrial problem. Based on standardized cryptographic solutions, we design an end-to-end data-protection scheme for low power networks. This scheme was deployed on the water distribution network in the City of Antibes, France.