1,605 research outputs found
Fully leakage-resilient signatures revisited: Graceful degradation, noisy leakage, and construction in the bounded-retrieval model
We construct new leakage-resilient signature schemes. Our schemes remain unforgeable against an adversary leaking arbitrary (yet bounded) information on the entire state of the signer (sometimes known as fully leakage resilience), including the random coin tosses of the signing algorithm. The main feature of our constructions is that they offer a graceful degradation of security in situations where standard existential unforgeability is impossible
Cloud Data Auditing Using Proofs of Retrievability
Cloud servers offer data outsourcing facility to their clients. A client
outsources her data without having any copy at her end. Therefore, she needs a
guarantee that her data are not modified by the server which may be malicious.
Data auditing is performed on the outsourced data to resolve this issue.
Moreover, the client may want all her data to be stored untampered. In this
chapter, we describe proofs of retrievability (POR) that convince the client
about the integrity of all her data.Comment: A version has been published as a book chapter in Guide to Security
Assurance for Cloud Computing (Springer International Publishing Switzerland
2015
Quantum Cryptography Beyond Quantum Key Distribution
Quantum cryptography is the art and science of exploiting quantum mechanical
effects in order to perform cryptographic tasks. While the most well-known
example of this discipline is quantum key distribution (QKD), there exist many
other applications such as quantum money, randomness generation, secure two-
and multi-party computation and delegated quantum computation. Quantum
cryptography also studies the limitations and challenges resulting from quantum
adversaries---including the impossibility of quantum bit commitment, the
difficulty of quantum rewinding and the definition of quantum security models
for classical primitives. In this review article, aimed primarily at
cryptographers unfamiliar with the quantum world, we survey the area of
theoretical quantum cryptography, with an emphasis on the constructions and
limitations beyond the realm of QKD.Comment: 45 pages, over 245 reference
PROPYLA: Privacy Preserving Long-Term Secure Storage
An increasing amount of sensitive information today is stored electronically
and a substantial part of this information (e.g., health records, tax data,
legal documents) must be retained over long time periods (e.g., several decades
or even centuries). When sensitive data is stored, then integrity and
confidentiality must be protected to ensure reliability and privacy. Commonly
used cryptographic schemes, however, are not designed for protecting data over
such long time periods. Recently, the first storage architecture combining
long-term integrity with long-term confidentiality protection was proposed
(AsiaCCS'17). However, the architecture only deals with a simplified storage
scenario where parts of the stored data cannot be accessed and verified
individually. If this is allowed, however, not only the data content itself,
but also the access pattern to the data (i.e., the information which data items
are accessed at which times) may be sensitive information. Here we present the
first long-term secure storage architecture that provides long-term access
pattern hiding security in addition to long-term integrity and long-term
confidentiality protection. To achieve this, we combine information-theoretic
secret sharing, renewable timestamps, and renewable commitments with an
information-theoretic oblivious random access machine. Our performance analysis
of the proposed architecture shows that achieving long-term integrity,
confidentiality, and access pattern hiding security is feasible.Comment: Few changes have been made compared to proceedings versio
Lime: Data Lineage in the Malicious Environment
Intentional or unintentional leakage of confidential data is undoubtedly one
of the most severe security threats that organizations face in the digital era.
The threat now extends to our personal lives: a plethora of personal
information is available to social networks and smartphone providers and is
indirectly transferred to untrustworthy third party and fourth party
applications.
In this work, we present a generic data lineage framework LIME for data flow
across multiple entities that take two characteristic, principal roles (i.e.,
owner and consumer). We define the exact security guarantees required by such a
data lineage mechanism toward identification of a guilty entity, and identify
the simplifying non repudiation and honesty assumptions. We then develop and
analyze a novel accountable data transfer protocol between two entities within
a malicious environment by building upon oblivious transfer, robust
watermarking, and signature primitives. Finally, we perform an experimental
evaluation to demonstrate the practicality of our protocol
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