Hybrid Encryption in a Multi-user Setting, Revisited

Abstract

This paper contributes to understanding the interplay of security notions for PKE, KEMs, and DEMs, in settings with multiple users, challenges, and instances. We start analytically by first studying (a) the tightness aspects of the standard hybrid KEM+DEM encryption paradigm, (b) the inherent weak security properties of all deterministic DEMs due to generic key-collision attacks in the multi-instance setting, and (c) the negative effect of deterministic DEMs on the security of hybrid encryption.We then switch to the constructive side by (d) introducing the concept of an augmented data encapsulation mechanism (ADEM) that promises robustness against multi-instance attacks, (e) proposing a variant of hybrid encryption that uses an ADEM instead of a DEM to alleviate the problems of the standard KEM+DEM composition, and (f) constructing practical ADEMs that are secure in the multi-instance setting.

Heterogeneous deniable authenticated encryption for location-based services

“…Abe et al [20] put forward to a more efficient tag-KEM/DEM scheme. Then, many KEM/ DEM schemes [21][22][23][24][25][26][27][28] have been proposed. These designs support both components modular design.…”

Critical perspectives on provable security: Fifteen years of "another look" papers

“…Considerable work has been done in recent years on designing cryptographic protocols that have reductionist security proofs in the multi-user setting whose tightness gaps do not (significantly) depend on the number of users. Examples include MAC schemes [29], signature schemes [203], aggregate signature schemes [223], Galois counter mode (GCM) in authenticated encryption [230], hybrid encryption [159], and key agreement [18].…”

A hybrid encryption system for communication and financial transactions using RSA and a novel symmetric key algorithm

“…Consequently, hybrid algorithm techniques provide a new class of algorithms [20], [21]. A hybrid scheme provides more data confidentiality which is to be achieved by this hybrid cryptosystem which contains all the interchangeable and dissimilar cryptography rules [22], [23]. In order to ensure safe communication and secure transactions, there are several factors to consider, including the type of channel used, the business model, and the associated security infrastructure.…”