[Resource Topic] 2016/534: Damaging, Simplifying, and Salvaging p-OMD

Welcome to the resource topic for 2016/534

Damaging, Simplifying, and Salvaging p-OMD

Authors: Tomer Ashur, Bart Mennink


One of the submissions to the CAESAR competition for the design of a new authenticated encryption scheme is Offset Merkle-Damgård (OMD). At FSE 2015, Reyhanitabar et al. introduced p-OMD, an improvement of OMD that processes the associated data almost for free. As an extra benefit, p-OMD was claimed to offer integrity against nonce-misusing adversaries, a property that OMD does not have. In this work we show how a nonce-misusing adversary can forge a message for the original p-OMD using only 3 queries (including the forgery). As a second contribution, we generalize and simplify p-OMD. This is done via the introduction of the authenticated encryption scheme Spoed. The most important difference is the usage of a generalized padding function GPAD, which neatly eliminates the need for a case distinction in the design specification and therewith allows for a significantly shorter description of the scheme and a better security bound. Finally, we introduce the authenticated encryption scheme Spoednic, a variant of Spoed providing authenticity against a nonce-misusing adversary at a modest price.

ePrint: https://eprint.iacr.org/2016/534

See all topics related to this paper.

Feel free to post resources that are related to this paper below.

Example resources include: implementations, explanation materials, talks, slides, links to previous discussions on other websites.

For more information, see the rules for Resource Topics .