[Resource Topic] 1998/012: Maintaining Authenticated Communication in the Presence of Break-ins

Welcome to the resource topic for 1998/012

Maintaining Authenticated Communication in the Presence of Break-ins

Authors: Ran Canetti, Shai Halevi, Amir Herzberg


We study the problem of maintaining authenticated communication over untrusted
communication channels, in a scenario where the communicating parties may be
occasionally and repeatedly broken into for transient periods of time. Once
a party is broken into, its cryptographic keys are exposed and perhaps
modified. Yet, we want parties whose security is thus compromised to regain
their ability to communicate in an authenticated way aided by other parties.
In this work we present a mathematical model for this highly adversarial
setting, exhibiting salient properties and parameters, and then describe
a practically-appealing protocol for the task of maintaining authenticated
communication in this model.

A key element in our solution is devising {\em proactive distributed signature
(PDS) schemes} in our model. Although PDS schemes are known in the literature,
they are all designed for a model where authenticated communication and
broadcast primitives are available. We therefore show how these schemes can be
modified to work in our model, where no such primitives are available a-priori.
In the process of devising the above schemes, we also present a new definition
of PDS schemes (and of distributed signature schemes in general). This
definition may be of independent interest.

ePrint: https://eprint.iacr.org/1998/012

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