219,718 research outputs found
Ozone: Efficient Execution with Zero Timing Leakage for Modern Microarchitectures
Time variation during program execution can leak sensitive information. Time
variations due to program control flow and hardware resource contention have
been used to steal encryption keys in cipher implementations such as AES and
RSA. A number of approaches to mitigate timing-based side-channel attacks have
been proposed including cache partitioning, control-flow obfuscation and
injecting timing noise into the outputs of code. While these techniques make
timing-based side-channel attacks more difficult, they do not eliminate the
risks. Prior techniques are either too specific or too expensive, and all leave
remnants of the original timing side channel for later attackers to attempt to
exploit.
In this work, we show that the state-of-the-art techniques in timing
side-channel protection, which limit timing leakage but do not eliminate it,
still have significant vulnerabilities to timing-based side-channel attacks. To
provide a means for total protection from timing-based side-channel attacks, we
develop Ozone, the first zero timing leakage execution resource for a modern
microarchitecture. Code in Ozone execute under a special hardware thread that
gains exclusive access to a single core's resources for a fixed (and limited)
number of cycles during which it cannot be interrupted. Memory access under
Ozone thread execution is limited to a fixed size uncached scratchpad memory,
and all Ozone threads begin execution with a known fixed microarchitectural
state. We evaluate Ozone using a number of security sensitive kernels that have
previously been targets of timing side-channel attacks, and show that Ozone
eliminates timing leakage with minimal performance overhead
Delegating Quantum Computation in the Quantum Random Oracle Model
A delegation scheme allows a computationally weak client to use a server's
resources to help it evaluate a complex circuit without leaking any information
about the input (other than its length) to the server. In this paper, we
consider delegation schemes for quantum circuits, where we try to minimize the
quantum operations needed by the client. We construct a new scheme for
delegating a large circuit family, which we call "C+P circuits". "C+P" circuits
are the circuits composed of Toffoli gates and diagonal gates. Our scheme is
non-interactive, requires very little quantum computation from the client
(proportional to input length but independent of the circuit size), and can be
proved secure in the quantum random oracle model, without relying on additional
assumptions, such as the existence of fully homomorphic encryption. In practice
the random oracle can be replaced by an appropriate hash function or block
cipher, for example, SHA-3, AES.
This protocol allows a client to delegate the most expensive part of some
quantum algorithms, for example, Shor's algorithm. The previous protocols that
are powerful enough to delegate Shor's algorithm require either many rounds of
interactions or the existence of FHE. The protocol requires asymptotically
fewer quantum gates on the client side compared to running Shor's algorithm
locally.
To hide the inputs, our scheme uses an encoding that maps one input qubit to
multiple qubits. We then provide a novel generalization of classical garbled
circuits ("reversible garbled circuits") to allow the computation of Toffoli
circuits on this encoding. We also give a technique that can support the
computation of phase gates on this encoding.
To prove the security of this protocol, we study key dependent message(KDM)
security in the quantum random oracle model. KDM security was not previously
studied in quantum settings.Comment: 41 pages, 1 figures. Update to be consistent with the proceeding
versio
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
S-FaaS: Trustworthy and Accountable Function-as-a-Service using Intel SGX
Function-as-a-Service (FaaS) is a recent and already very popular paradigm in
cloud computing. The function provider need only specify the function to be
run, usually in a high-level language like JavaScript, and the service provider
orchestrates all the necessary infrastructure and software stacks. The function
provider is only billed for the actual computational resources used by the
function invocation. Compared to previous cloud paradigms, FaaS requires
significantly more fine-grained resource measurement mechanisms, e.g. to
measure compute time and memory usage of a single function invocation with
sub-second accuracy. Thanks to the short duration and stateless nature of
functions, and the availability of multiple open-source frameworks, FaaS
enables non-traditional service providers e.g. individuals or data centers with
spare capacity. However, this exacerbates the challenge of ensuring that
resource consumption is measured accurately and reported reliably. It also
raises the issues of ensuring computation is done correctly and minimizing the
amount of information leaked to service providers.
To address these challenges, we introduce S-FaaS, the first architecture and
implementation of FaaS to provide strong security and accountability guarantees
backed by Intel SGX. To match the dynamic event-driven nature of FaaS, our
design introduces a new key distribution enclave and a novel transitive
attestation protocol. A core contribution of S-FaaS is our set of resource
measurement mechanisms that securely measure compute time inside an enclave,
and actual memory allocations. We have integrated S-FaaS into the popular
OpenWhisk FaaS framework. We evaluate the security of our architecture, the
accuracy of our resource measurement mechanisms, and the performance of our
implementation, showing that our resource measurement mechanisms add less than
6.3% latency on standardized benchmarks
Detection loophole attacks on semi-device-independent quantum and classical protocols
Semi-device-independent quantum protocols realize information tasks - e.g.
secure key distribution, random access coding, and randomness generation - in a
scenario where no assumption on the internal working of the devices used in the
protocol is made, except their dimension. These protocols offer two main
advantages: first, their implementation is often less demanding than
fully-device-independent protocols. Second, they are more secure than their
device-dependent counterparts. Their classical analogous is represented by
random access codes, which provide a general framework for describing one-sided
classical communication tasks. We discuss conditions under which detection
inefficiencies can be exploited by a malicious provider to fake the performance
of semi-device-independent quantum and classical protocols - and how to prevent
it.Comment: 13 pages, 1 figure, published versio
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