6,058 research outputs found
fVSS: A New Secure and Cost-Efficient Scheme for Cloud Data Warehouses
Cloud business intelligence is an increasingly popular choice to deliver
decision support capabilities via elastic, pay-per-use resources. However, data
security issues are one of the top concerns when dealing with sensitive data.
In this pa-per, we propose a novel approach for securing cloud data warehouses
by flexible verifiable secret sharing, fVSS. Secret sharing encrypts and
distributes data over several cloud ser-vice providers, thus enforcing data
privacy and availability. fVSS addresses four shortcomings in existing secret
sharing-based approaches. First, it allows refreshing the data ware-house when
some service providers fail. Second, it allows on-line analysis processing.
Third, it enforces data integrity with the help of both inner and outer
signatures. Fourth, it helps users control the cost of cloud warehousing by
balanc-ing the load among service providers with respect to their pricing
policies. To illustrate fVSS' efficiency, we thoroughly compare it with
existing secret sharing-based approaches with respect to security features,
querying power and data storage and computing costs
On the Impossibility of Surviving (Iterated) Deletion of Weakly Dominated Strategies in Rational MPC
Rational multiparty computation (rational MPC) provides a framework for analyzing MPC protocols through the lens of game theory. One way to judge whether an MPC protocol is rational is through weak domination: Rational players would not adhere to an MPC protocol if deviating never decreases their utility, but sometimes increases it. Secret reconstruction protocols are of particular importance in this setting because they represent the last phase of most (rational) MPC protocols. We show that most secret reconstruction protocols from the literature are not, in fact, stable with respect to weak domination. Furthermore, we formally prove that (under certain assumptions) it is impossible to design a secret reconstruction protocol which is a Nash equlibrium but not weakly dominated if (1) shares are authenticated or (2) half of all players may form a coalition
Multi-party Quantum Computation
We investigate definitions of and protocols for multi-party quantum computing
in the scenario where the secret data are quantum systems. We work in the
quantum information-theoretic model, where no assumptions are made on the
computational power of the adversary. For the slightly weaker task of
verifiable quantum secret sharing, we give a protocol which tolerates any t <
n/4 cheating parties (out of n). This is shown to be optimal. We use this new
tool to establish that any multi-party quantum computation can be securely
performed as long as the number of dishonest players is less than n/6.Comment: Masters Thesis. Based on Joint work with Claude Crepeau and Daniel
Gottesman. Full version is in preparatio
Manifesting Unobtainable Secrets: Threshold Elliptic Curve Key Generation using Nested Shamir Secret Sharing
We present a mechanism to manifest unobtainable secrets using a nested Shamir
secret sharing scheme to create public/private key pairs for elliptic curves. A
threshold secret sharing scheme can be used as a decentralised trust mechanism
with applications in identity validation, message decryption, and agreement
empowerment. Decentralising trust means that there is no single point
vulnerability which could enable compromise of a system. Our primary interest
is in twisted Edwards curves as used in EdDSA, and the related Diffie-Hellman
key-exchange algorithms. The key generation is also decentralised, so can be
used as a decentralised secret RNG suitable for use in other algorithms. The
algorithms presented could be used to fill a ``[TBS]'' in the draft IETF
specification ``Threshold modes in elliptic curves'' published in 2020 and
updated in 2022
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