250 research outputs found
Two-message quantum interactive proofs and the quantum separability problem
Suppose that a polynomial-time mixed-state quantum circuit, described as a
sequence of local unitary interactions followed by a partial trace, generates a
quantum state shared between two parties. One might then wonder, does this
quantum circuit produce a state that is separable or entangled? Here, we give
evidence that it is computationally hard to decide the answer to this question,
even if one has access to the power of quantum computation. We begin by
exhibiting a two-message quantum interactive proof system that can decide the
answer to a promise version of the question. We then prove that the promise
problem is hard for the class of promise problems with "quantum statistical
zero knowledge" (QSZK) proof systems by demonstrating a polynomial-time Karp
reduction from the QSZK-complete promise problem "quantum state
distinguishability" to our quantum separability problem. By exploiting Knill's
efficient encoding of a matrix description of a state into a description of a
circuit to generate the state, we can show that our promise problem is NP-hard
with respect to Cook reductions. Thus, the quantum separability problem (as
phrased above) constitutes the first nontrivial promise problem decidable by a
two-message quantum interactive proof system while being hard for both NP and
QSZK. We also consider a variant of the problem, in which a given
polynomial-time mixed-state quantum circuit accepts a quantum state as input,
and the question is to decide if there is an input to this circuit which makes
its output separable across some bipartite cut. We prove that this problem is a
complete promise problem for the class QIP of problems decidable by quantum
interactive proof systems. Finally, we show that a two-message quantum
interactive proof system can also decide a multipartite generalization of the
quantum separability problem.Comment: 34 pages, 6 figures; v2: technical improvements and new result for
the multipartite quantum separability problem; v3: minor changes to address
referee comments, accepted for presentation at the 2013 IEEE Conference on
Computational Complexity; v4: changed problem names; v5: updated references
and added a paragraph to the conclusion to connect with prior work on
separability testin
Quantum interactive proofs and the complexity of separability testing
We identify a formal connection between physical problems related to the
detection of separable (unentangled) quantum states and complexity classes in
theoretical computer science. In particular, we show that to nearly every
quantum interactive proof complexity class (including BQP, QMA, QMA(2), and
QSZK), there corresponds a natural separability testing problem that is
complete for that class. Of particular interest is the fact that the problem of
determining whether an isometry can be made to produce a separable state is
either QMA-complete or QMA(2)-complete, depending upon whether the distance
between quantum states is measured by the one-way LOCC norm or the trace norm.
We obtain strong hardness results by proving that for each n-qubit maximally
entangled state there exists a fixed one-way LOCC measurement that
distinguishes it from any separable state with error probability that decays
exponentially in n.Comment: v2: 43 pages, 5 figures, completely rewritten and in Theory of
Computing (ToC) journal forma
Secure Authentication in the Grid: A Formal Analysis of DNP3: SAv5
Most of the world’s power grids are controlled remotely. Their control messages are sent over potentially insecure channels, driving the need for an authentication mechanism. The main communication mechanism for power grids and other utilities is defined by an IEEE standard, referred to as DNP3; this includes the Secure Authentication v5 (SAv5) protocol, which aims to ensure that messages are authenticated. We provide the first security analysis of the complete DNP3: SAv5 protocol. Previous work has considered the message-passing sub-protocol of SAv5 in isolation, and considered some aspects of the intended security properties. In contrast, we formally model and analyse the complex composition of the protocol’s three sub-protocols. In doing so, we consider the full state machine, and the possibility of cross-protocol attacks. Furthermore, we model fine-grained security properties that closely match the standard’s intended security properties. For our analysis, we leverage the Tamarin prover for the symbolic analysis of security protocols. Our analysis shows that the core DNP3: SAv5 design meets its intended security properties. Notably, we show that a previously reported attack does not apply to the standard. However, our analysis also leads to several concrete recommendations for improving future versions of the standard
Automatically Detecting the Misuse of Secrets: Foundations, Design Principles, and Applications
We develop foundations and several constructions for security protocols that can automatically detect, without false positives, if a secret (such as a key or password) has been misused. Such constructions can be used, e.g., to automatically shut down compromised services, or to automatically revoke misused secrets to minimize the effects of compromise. Our threat model includes malicious agents, (temporarily or permanently) compromised agents, and clones.
Previous works have studied domain-specific partial solutions to this problem. For example, Google’s Certificate Transparency aims to provide infrastructure to detect the misuse of a certificate authority’s signing key, logs have been used for detecting endpoint compromise, and protocols have been proposed to detect cloned RFID/smart cards. Contrary to these existing approaches, for which the designs are interwoven with domain-specific considerations and which usually do not enable fully automatic response (i.e., they need human assessment), our approach shows where automatic action is possible. Our results unify, provide design rationales, and suggest improvements for the existing domain-specific solutions.
Based on our analysis, we construct several mechanisms for the detection of misuse. Our mechanisms enable automatic response, such as revoking keys or shutting down services, thereby substantially limiting the impact of a compromise. In several case studies, we show how our mechanisms can be used to substantially increase the security guarantees of a wide range of systems, such as web logins, payment systems, or electronic door locks. For example, we propose and formally verify an improved version of Cloudflare’s Keyless SSL protocol that enables key misuse detection
Disparate data integration case for connected factories using timestamps
Manufacturing data integration of machine, process, and sensor data from the shop floor remains an important issue to achieve the anticipated business value of fully connected factories. Integrated manufacturing data has been a hallmark of Industry 4.0 initiatives, because integrated data precipitates better decision-making for cost, schedule, and system optimizations. In this paper, we extend work on optimizing manufacturing costs, describing an algorithm using timestamps to integrate previously unassociated quality and test information, enabling us to better identify and eliminate redundant tests. Results are provided and discussed, and we suggest the approach described may be valuable for some types of heterogeneous manufacturing data integration where timestamps and event chronologies are available
Factor determinante en la calificaciĂłn fiscal en las denuncias por violencia psicolĂłgica, Segunda FiscalĂa Provincial Penal Corporativa de Huaraz, 2020
La presente tesis se denomina “Cuál es el factor determinante en la calificación
fiscal en las denuncias por violencia psicolĂłgica, en la segunda fiscalĂa
provincial penal corporativa de Huaraz, 2020”, de tal manera que, su objetivo
general fue, Determinar cuál es el factor determinante en la decisión fiscal, en
las denuncias por violencia psicolĂłgica en la segunda fiscalĂa provincial penal
corporativa de Huaraz. Es asà que se desarrolló bajo el método cuantitativo el
cual estuvo basado en la aplicaciĂłn de una encuesta que fue dirigida a fiscales
del distrito fiscal de Ancash. Luego de análisis se determinó que en aquellos
donde existe una denuncia por violencia familiar bajo la modalidad de violencia
psicolĂłgica, el factor determinante viene a ser la pericia psicolĂłgica, toda vez
que los fiscales encuestados, sostuvieron en su mayorĂa, que solo se basan
en la pericia para calificar el hecho como delito o no, cosa errada, sin embargo,
ya que consideramos que es necesario recurrir a otros medios de prueba para
esclarecer los hechos de forma más correcta
Secure Authentication in the Grid: A Formal Analysis of DNP3 SAv5
Most of the world's power grids are controlled remotely. Their control messages are sent over potentially insecure channels, driving the need for an authentication mechanism. The main communication mechanism for power grids and other utilities is defined by an IEEE
standard, referred to as DNP3; this includes the Secure Authentication v5 (SAv5) protocol, which aims to ensure that messages are authenticated.
We provide the first security analysis of the complete DNP3: SAv5 protocol. Previous work has considered the message-passing sub-protocol of SAv5 in isolation, and considered some aspects of the intended security properties. In contrast, we formally model and analyse the complex composition of the protocol's sub-protocols. In doing so, we consider the full state machine, the protocol's asymmetric mode, and the possibility of cross-protocol attacks. Furthermore, we model fine-grained security properties that closely match the standard's intended security properties. For our analysis, we leverage the Tamarin prover for the symbolic analysis of security protocols.
Our analysis shows that the core DNP3: SAv5 design meets its intended security properties. Notably, we show that a previously reported attack does not apply to the standard. However, our analysis also leads to several concrete recommendations for improving future versions of the standard
Automatically Detecting the Misuse of Secrets: Foundations, Design Principles, and Applications
We develop foundations and several constructions for
security protocols that can automatically detect, without false
positives, if a secret (such as a key or password) has been misused.
Such constructions can be used, e.g., to automatically shut down
compromised services, or to automatically revoke misused secrets to
minimize the effects of compromise.
Our threat model includes malicious agents, (temporarily or permanently)
compromised agents, and clones.
Previous works have studied domain-specific partial solutions to this
problem. For example, Google's Certificate Transparency aims to provide
infrastructure to detect the misuse of a certificate authority's signing
key, logs have been used for detecting endpoint compromise, and
protocols have been proposed to detect cloned RFID/smart cards.
Contrary to these existing approaches, for which the designs are
interwoven with domain-specific considerations and which usually do not
enable fully automatic response (i.e., they need human assessment), our
approach shows where automatic action is possible. Our results
unify, provide design rationales, and suggest improvements for the
existing domain-specific solutions.
Based on our analysis, we construct several mechanisms for the detection
of misuse. Our mechanisms enable automatic response, such as revoking
keys or shutting down services, thereby substantially limiting the
impact of a compromise.
In several case studies, we show how our mechanisms can be used to
substantially increase the security guarantees of a wide range of
systems, such as web logins, payment systems, or electronic door locks.
For example, we propose and formally verify an improved version of
Cloudflare's Keyless SSL protocol that enables key misuse detection
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