301 research outputs found
Sparsity in Dynamics of Spontaneous Subtle Emotions: Analysis \& Application
Spontaneous subtle emotions are expressed through micro-expressions, which
are tiny, sudden and short-lived dynamics of facial muscles; thus poses a great
challenge for visual recognition. The abrupt but significant dynamics for the
recognition task are temporally sparse while the rest, irrelevant dynamics, are
temporally redundant. In this work, we analyze and enforce sparsity constrains
to learn significant temporal and spectral structures while eliminate
irrelevant facial dynamics of micro-expressions, which would ease the challenge
in the visual recognition of spontaneous subtle emotions. The hypothesis is
confirmed through experimental results of automatic spontaneous subtle emotion
recognition with several sparsity levels on CASME II and SMIC, the only two
publicly available spontaneous subtle emotion databases. The overall
performances of the automatic subtle emotion recognition are boosted when only
significant dynamics are preserved from the original sequences.Comment: IEEE Transaction of Affective Computing (2016
Enriched Long-term Recurrent Convolutional Network for Facial Micro-Expression Recognition
Facial micro-expression (ME) recognition has posed a huge challenge to
researchers for its subtlety in motion and limited databases. Recently,
handcrafted techniques have achieved superior performance in micro-expression
recognition but at the cost of domain specificity and cumbersome parametric
tunings. In this paper, we propose an Enriched Long-term Recurrent
Convolutional Network (ELRCN) that first encodes each micro-expression frame
into a feature vector through CNN module(s), then predicts the micro-expression
by passing the feature vector through a Long Short-term Memory (LSTM) module.
The framework contains two different network variants: (1) Channel-wise
stacking of input data for spatial enrichment, (2) Feature-wise stacking of
features for temporal enrichment. We demonstrate that the proposed approach is
able to achieve reasonably good performance, without data augmentation. In
addition, we also present ablation studies conducted on the framework and
visualizations of what CNN "sees" when predicting the micro-expression classes.Comment: Published in Micro-Expression Grand Challenge 2018, Workshop of 13th
IEEE Facial & Gesture 201
Less is More: Micro-expression Recognition from Video using Apex Frame
Despite recent interest and advances in facial micro-expression research,
there is still plenty room for improvement in terms of micro-expression
recognition. Conventional feature extraction approaches for micro-expression
video consider either the whole video sequence or a part of it, for
representation. However, with the high-speed video capture of micro-expressions
(100-200 fps), are all frames necessary to provide a sufficiently meaningful
representation? Is the luxury of data a bane to accurate recognition? A novel
proposition is presented in this paper, whereby we utilize only two images per
video: the apex frame and the onset frame. The apex frame of a video contains
the highest intensity of expression changes among all frames, while the onset
is the perfect choice of a reference frame with neutral expression. A new
feature extractor, Bi-Weighted Oriented Optical Flow (Bi-WOOF) is proposed to
encode essential expressiveness of the apex frame. We evaluated the proposed
method on five micro-expression databases: CAS(ME), CASME II, SMIC-HS,
SMIC-NIR and SMIC-VIS. Our experiments lend credence to our hypothesis, with
our proposed technique achieving a state-of-the-art F1-score recognition
performance of 61% and 62% in the high frame rate CASME II and SMIC-HS
databases respectively.Comment: 14 pages double-column, author affiliations updated, acknowledgment
of grant support adde
Cryptanalysis of a new ultralightweight RFID authentication protocol—SASI
Since RFID tags are ubiquitous and at times even oblivious to the
human user, all modern RFID protocols are designed to resist tracking so that the
location privacy of the human RFID user is not violated. Another design criterion
for RFIDs is the low computational effort required for tags, in view that most tags
are passive devices that derive power from an RFID reader’s signals. Along this
vein, a class of ultralightweight RFID authentication protocols has been designed,
which uses only the most basic bitwise and arithmetic operations like exclusive-
OR, OR, addition, rotation, and so forth. In this paper, we analyze the security of
the SASI protocol, a recently proposed ultralightweight RFID protocol with better
claimed security than earlier protocols. We show that SASI does not achieve
resistance to tracking, which is one of its design objectives
Non-repudiable authentication and billing architecture for wireless mesh networks
Wireless mesh networks (WMNs) are a kind of wireless ad hoc networks
that are multi-hop where packets are forwarded from source to destination
by intermediate notes as well as routers that form a kind of network infrastructure
backbone. We investigate the security of the recently proposed first known secure
authentication and billing architecture for WMNs which eliminates the need for
bilateral roaming agreements and that for traditional home-foreign domains. We
show that this architecture does not securely provide incontestable billing contrary
to designer claims and furthermore it does not achieve entity authentication. We
then present an enhanced scheme that achieves entity authentication and nonrepudiable
billing
Fixing the integrated Diffie-Hellman-DSA key exchange protocol
Recently, three key exchange protocols were proposed that integrated the Diffie-Hellman key exchange into the digital signature algorithm (DSA). It was claimed that the protocols provide known-key security and unknown key-share resilience, while the most advanced variant also provides key-replay resilience. However, we show in this paper that the protocols do not provide forward secrecy and key freshness which are two of the standard security attributes that key exchange protocols should have. We also fix the protocols such that they provide these security attributes
Security limitations of an authorized anonymous ID-based scheme for mobile communication
In this article we discuss the security limitations of a recently proposed authorized anonymous ID-based scheme for mobile communications due to He et al. We present three example attacks an attacker could mount on the scheme, point out the weaknesses we exploited, and suggest how to counter them. Our attacks are variants of the replay attack to which any security scheme should be resistant. Such attacks are easy to mount since they simply require replaying previous valid messages, and are often passive attacks and thus hard to detect. Therefore, our results are devastating since they show that the scheme has failed to achieve its main objective of establishing mutual authentication between legitimate parties
Security of two recent constant-round password authenticated group key exchange schemes
When humans interact with machines in their daily networks, it is important that security of the communications is offered, and where the involved shared secrets used to achieve this are easily remembered by humans. Password-based authenticated group key exchange (PAGKE) schemes allow group users to share a session key based on a human-memorizable password. In this paper, we consider two PAGKE schemes that build on the seminal scheme of Burmester and Desmedt. Weshow an undetectable online dictionary attack on the first scheme, and exploit the partnering definition to break the key indistinguishability of the second scheme
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