35901095
The Computational SLR: A Logic for Reasoning about Computational Indistinguishability
Computational indistinguishability is a notion in complexity-theoretic cryptography and is used to define many security criteria. However, in traditional cryptography, proving computational indistinguishability is usually informal and becomes error-prone when cryptographic constructions are complex. This paper presents a formal proof system based on an extension of Hofmann's SLR language, which can capture probabilistic polynomial-time computations through typing and is sufficient for expressing cryptographic constructions. We in particular define rules that justify directly the computational indistinguishability between programs and prove that these rules are sound with respect to the set-theoretic semantics, hence the standard definition of security. We also show that it is applicable in cryptography by verifying, in our proof system, Goldreich and Micali's construction of pseudorandom generator.
12359586
Verifying Anonymous Credential Systems in Applied Pi Calculus
Anonymous credentials are widely used to certify properties of a credential owner or to support the owner to demand valuable services, while hiding the user's identity at the same time. A credential system (a.k.a. pseudonym system) usually consists of multiple interactive procedures between users and organizations, including generating pseudonyms, issuing credentials and verifying credentials, which are required to meet various security properties. We propose a general symbolic model (based on the applied pi calculus) for anonymous credential systems and give formal definitions of a few important security properties, including pseudonym and credential unforgeability, credential safety, pseudonym untraceability. We specialize the general formalization and apply it to the verification of a concrete anonymous credential system proposed by Camenisch and Lysyanskaya. The analysis is done automatically with the tool ProVerif and several security properties have been verified.
14270166
A Role-Based Approach in Dynamic Task Delegation in Agent Teamwork
This paper presents a role-based agent teamwork language called RoB-MALLET (Role-Based Multi-Agent Logic Language for Encoding Teamwork). Roles have been used to form multi-agent theories and guide the construction of multi-agent architectures and systems. Different from the most existing agent teamwork models that emphasize practical reasoning based on beliefs, desires and intentions (BDI), a role-based teamwork language stresses the concept of organization and thereby cooperation. RoB-MALLET is able to handle unexpected uncertainties and allow for the conceptual specification of teamwork knowledge for reuse. Finally, we present several experiments that explore plan reusability of RoB-MALLET, show that it is flexible in supporting simultaneity of invocation and evaluate its efficiency in supporting teamwork.
44325838
Simulating Wrinkles in Facial Expressions on an Anatomy-Based Face
This paper presents a muscle-driven wrinkle model for simulating dynamic wrinkles that appear during facial expressions, which is geometric in nature. Wrinkles are generated on an anatomy-based face model that incorporates a structure of skin, muscles and skull for physically-based animation. Corresponding to two types of facial muscles, a geometric model is developed to govern how the wrinkle amplitude evolves locally upon skin deformation, taking into account the properties of real wrinkles. During facial animation, wrinkles are generated in the local regions influenced by muscle contraction, simulating resistance to compression of tissues. Using our method, realistic wrinkles can be dynamically rendered on the adaptively refined face mesh at interactive rates.
16765186
Insider DoS Attacks on Epidemic Propagation Strategies of Network Reprogramming in Wireless Sensor Networks
Network reprogramming is a crucial service in wireless sensor networks (WSNs) that relies on epidemic strategy for spreading software updates by just having a local view of the networks. Securing the process of network reprogramming is essential in some certain WSNs applications, state-of-the-art secure network reprogramming protocols for WSNs aim for the efficient source authentication and integrity verification of code image, however, due to the resource constrains of WSNs, existing secure network reprogramming protocols are vulnerable to Denial of Service (DoS) attacks when sensor nodes can be compromised (insider DoS attacks). In this paper, we identify different types of DoS attacks exploiting the epidemic propagation strategies used by Deluge and propose corresponding analysis models to attempt to quantify the cost of these attacks damage. Simulation further shows the impact of insider DoS attacks on network reprogramming in WSNs.
40389264
Application of Efficient Numerical Methods in Solution of Ordinary Differential Equations for Modeling Electrical Activity in Cardiac Cells
There is a large number of ordinary differential equations (ODEs) characterize the electrical behavior generated by ionic movements in human myocardial cell. In this paper, several approaches were investigated in order to improve the efficiency of solving the ODE systems for ten Tusscher et al.’s ionic model of human ventricular tissue. By using non-standard finite difference (NSFD) scheme, the stiffness of the ODEs system will be successfully reduced, so a larger step-size can be used. A popular multi-step method called backward differentiation formulation (BDF) was also incorporated into the computational model for testing the largest possible time steps. The results show that NSFD can be as much as 10 times more efficient than standard forward Euler in single cell model simulation while maintaining an acceptable level of accuracy. The investigation of BDF method shows that a large step size is not recommended for the single cell simulation application. All solvers were coupled to the partial differential equations for the complete simulation of heart tissue, and such computation scheme may be a good calculation technique in heart modeling and simulation.
1171092
On Completeness of Logical Relations for Monadic Types
Software security can be ensured by specifying and verifying security properties of software using formal methods with strong theoretical bases. In particular, programs can be modeled in the framework of lambda-calculi, and interesting properties can be expressed formally by contextual equivalence (a.k.a. observational equivalence). Furthermore, imperative features, which exist in most real-life software, can be nicely expressed in the so-called computational lambda-calculus. Contextual equivalence is difficult to prove directly, but we can often use logical relations as a tool to establish it in lambda-calculi. We have already defined logical relations for the computational lambda-calculus in previous work. We devote this paper to the study of their completeness w.r.t. contextual equivalence in the computational lambda-calculus.