Distributed Storage for Data Security

TL;DR

This paper analyzes the security of distributed password storage, characterizing the maximum guessing difficulty for eavesdroppers while ensuring legitimate users can reliably retrieve passwords.

Contribution

It provides a theoretical characterization of the optimal secrecy exponent in a distributed storage system with partial eavesdropper access.

Findings

Maximized the guessing exponent for Eve under system constraints

Established conditions for reliable password retrieval by Bob

Quantified the trade-off between security and retrieval reliability

Abstract

We study the secrecy of a distributed storage system for passwords. The encoder, Alice, observes a length-n password and describes it using two hints, which she then stores in different locations. The legitimate receiver, Bob, observes both hints. The eavesdropper, Eve, sees only one of the hints; Alice cannot control which. We characterize the largest normalized (by n) exponent that we can guarantee for the number of guesses it takes Eve to guess the password subject to the constraint that either the number of guesses it takes Bob to guess the password or the size of the list that Bob must form to guarantee that it contain the password approach 1 as n tends to infinity.