posted on 2024-07-25, 12:38authored byChandranan Dhar, Jordan EthanJordan Ethan, Ravindra Jejurikar, Mustafa Khairallah, Eik List, Sougata Mandal
During recent years, research on authenticated encryption has been thriving through two highly active and practically motivated research directions: provable leakage resilience and key- or context-commitment security. However, the intersection of both fields had been overlooked until very recently. In ToSC 1/2024, Struck and Weishäupl studied generic compositions of encryption schemes and message authentication codes for building committing leakage-resilient schemes. They showed that, in general, Encrypt-then-MAC (EtM) and MAC-then-Encrypt (MtE) are not committing while Encrypt-and-MAC (EaM) is, under plausible and weak assumptions on the components. However, real-world schemes are rarely strict blackbox constructions. Instead, while various leakage-resilient schemes follow blueprints inspired by generic compositions, they often tweak them for security or efficiency.
In this paper, we study two blueprints, the first one based on EtM for one of the strongest possible levels of leakage resilience. The second one is a single-pass framework based on leveled implementations. We show that, with a careful selection of the underlying primitives such as with identical encryption and authentication keys and a collision-resistant PRF as the MAC, these blueprints are committing. Our results do not contradict the results by Struck and Weishäupl since we pose more, but practically-motivated, requirements on the components. We demonstrate the practical relevance of our results by showing that our results on those blueprints allow us to easily derive proofs that several state-of-the-art leakage-resilient schemes are indeed committing, including TEDT and its descendants TEDT2 and Romulus-T, as well as the single-pass scheme Triplex.
History
Primary Research Area
Algorithmic Foundations and Cryptography
Journal
IACR Transactions on Symmetric Cryptology
Volume
2024
Page Range
348-370
Publisher
Ruhr-Universität Bochum
Open Access Type
Gold
Sub Type
Article
BibTeX
@article{Dhar:Ethan:Jejurikar:Khairallah:List:Mandal:2024,
title = "Context-Committing Security of Leveled Leakage-Resilient AEAD",
author = "Dhar, Chandranan" AND "Ethan, Jordan" AND "Jejurikar, Ravindra" AND "Khairallah, Mustafa" AND "List, Eik" AND "Mandal, Sougata",
year = 2024,
month = 6,
journal = "IACR Transactions on Symmetric Cryptology",
number = "2",
pages = "348--370",
publisher = "Ruhr-Universität Bochum",
issn = "2519-173X",
doi = "10.46586/tosc.v2024.i2.348-370"
}