11,272 research outputs found
Finding Safety in Numbers with Secure Allegation Escrows
For fear of retribution, the victim of a crime may be willing to report it
only if other victims of the same perpetrator also step forward. Common
examples include 1) identifying oneself as the victim of sexual harassment,
especially by a person in a position of authority or 2) accusing an influential
politician, an authoritarian government, or ones own employer of corruption. To
handle such situations, legal literature has proposed the concept of an
allegation escrow: a neutral third-party that collects allegations anonymously,
matches them against each other, and de-anonymizes allegers only after
de-anonymity thresholds (in terms of number of co-allegers), pre-specified by
the allegers, are reached.
An allegation escrow can be realized as a single trusted third party;
however, this party must be trusted to keep the identity of the alleger and
content of the allegation private. To address this problem, this paper
introduces Secure Allegation Escrows (SAE, pronounced "say"). A SAE is a group
of parties with independent interests and motives, acting jointly as an escrow
for collecting allegations from individuals, matching the allegations, and
de-anonymizing the allegations when designated thresholds are reached. By
design, SAEs provide a very strong property: No less than a majority of parties
constituting a SAE can de-anonymize or disclose the content of an allegation
without a sufficient number of matching allegations (even in collusion with any
number of other allegers). Once a sufficient number of matching allegations
exist, the join escrow discloses the allegation with the allegers' identities.
We describe how SAEs can be constructed using a novel authentication protocol
and a novel allegation matching and bucketing algorithm, provide formal proofs
of the security of our constructions, and evaluate a prototype implementation,
demonstrating feasibility in practice.Comment: To appear in NDSS 2020. New version includes improvements to writing
and proof. The protocol is unchange
Beyond the Hype: On Using Blockchains in Trust Management for Authentication
Trust Management (TM) systems for authentication are vital to the security of
online interactions, which are ubiquitous in our everyday lives. Various
systems, like the Web PKI (X.509) and PGP's Web of Trust are used to manage
trust in this setting. In recent years, blockchain technology has been
introduced as a panacea to our security problems, including that of
authentication, without sufficient reasoning, as to its merits.In this work, we
investigate the merits of using open distributed ledgers (ODLs), such as the
one implemented by blockchain technology, for securing TM systems for
authentication. We formally model such systems, and explore how blockchain can
help mitigate attacks against them. After formal argumentation, we conclude
that in the context of Trust Management for authentication, blockchain
technology, and ODLs in general, can offer considerable advantages compared to
previous approaches. Our analysis is, to the best of our knowledge, the first
to formally model and argue about the security of TM systems for
authentication, based on blockchain technology. To achieve this result, we
first provide an abstract model for TM systems for authentication. Then, we
show how this model can be conceptually encoded in a blockchain, by expressing
it as a series of state transitions. As a next step, we examine five prevalent
attacks on TM systems, and provide evidence that blockchain-based solutions can
be beneficial to the security of such systems, by mitigating, or completely
negating such attacks.Comment: A version of this paper was published in IEEE Trustcom.
http://ieeexplore.ieee.org/document/8029486
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