48,954 research outputs found
A Semantic Hierarchy for Erasure Policies
We consider the problem of logical data erasure, contrasting with physical
erasure in the same way that end-to-end information flow control contrasts with
access control. We present a semantic hierarchy for erasure policies, using a
possibilistic knowledge-based semantics to define policy satisfaction such that
there is an intuitively clear upper bound on what information an erasure policy
permits to be retained. Our hierarchy allows a rich class of erasure policies
to be expressed, taking account of the power of the attacker, how much
information may be retained, and under what conditions it may be retained.
While our main aim is to specify erasure policies, the semantic framework
allows quite general information-flow policies to be formulated for a variety
of semantic notions of secrecy.Comment: 18 pages, ICISS 201
Just forget it - The semantics and enforcement of information erasure
Abstract. There are many settings in which sensitive information is made available to a system or organisation for a specific purpose, on the understanding that it will be erased once that purpose has been fulfilled. A familiar example is that of online credit card transactions: a customer typically provides credit card details to a payment system on the understanding that the following promises are kept: (i) Noninterference (NI): the card details may flow to the bank (in order that the payment can be authorised) but not to other users of the system; (ii) Erasure: the payment system will not retain any record of the card details once the transaction is complete. This example shows that we need to reason about NI and erasure in combination, and that we need to consider interactive systems: the card details are used in the interaction between the principals, and then erased; without the interaction, the card details could be dispensed with altogether and erasure would be unnecessary. The contributions of this paper are as follows. (i) We show that an end-to-end erasure property can be encoded as a “flow sensitive ” noninterference property. (ii) By a judicious choice of language construct to support erasur
Quantum optical coherence can survive photon losses: a continuous-variable quantum erasure correcting code
A fundamental requirement for enabling fault-tolerant quantum information
processing is an efficient quantum error-correcting code (QECC) that robustly
protects the involved fragile quantum states from their environment. Just as
classical error-correcting codes are indispensible in today's information
technologies, it is believed that QECC will play a similarly crucial role in
tomorrow's quantum information systems. Here, we report on the first
experimental demonstration of a quantum erasure-correcting code that overcomes
the devastating effect of photon losses. Whereas {\it errors} translate, in an
information theoretic language, the noise affecting a transmission line, {\it
erasures} correspond to the in-line probabilistic loss of photons. Our quantum
code protects a four-mode entangled mesoscopic state of light against erasures,
and its associated encoding and decoding operations only require linear optics
and Gaussian resources. Since in-line attenuation is generally the strongest
limitation to quantum communication, much more than noise, such an
erasure-correcting code provides a new tool for establishing quantum optical
coherence over longer distances. We investigate two approaches for
circumventing in-line losses using this code, and demonstrate that both
approaches exhibit transmission fidelities beyond what is possible by classical
means.Comment: 5 pages, 4 figure
- …