The Design and Analysis of Message Authentication and Authenticated Encryption Schemes

TLDR: This thesis studies message authentication and authenticated encryption algorithms, which are symmetric-key solutions to providing data integrity and confidentiality, and introduces a new design, LightMAC, which enables keys to be used longer than typically possible and an existing construction, PMAC, is analyzed in depth for its potential to provide more security than what was commonly thought.

Abstract: Awareness of the significance of securing communication and data has increased dramatically due to the countless examples showing that systems with little or no protection can and will be attacked. Lack of adoption, or improper use of strong cryptographic techniques could be attributed to the fact that cryptographic solutions are not efficient enough, impose impractical constraints on their use, or their analysis does not align with how they are used in practice. This thesis studies message authentication and authenticated encryption algorithms, which are symmetric-key solutions to providing data integrity and confidentiality. A formal study is performed of how security degrades when authenticated encryption algorithms are implemented in environments where theoretical assumptions might not be met, the so-called nonce abuse and release of unverified plaintext settings. Designs for authenticated encryption schemes are analyzed, including our designs COPA and COBRA, while keeping efficiency constraints in mind. Additionally, limits imposed by constrained environments, which commonly appear in applications for the internet of things, are considered, and discussed in the context of message authentication algorithms. A new design is introduced, LightMAC, which enables keys to be used longer than typically possible, and an existing construction, PMAC, is analyzed in depth for its potential to provide more security than what was commonly thought.