Security In Presence Research Articles

Probabilistic Security-Constrained Preventive Control under Forecast Uncertainties Including Volt/Var Constraints

The continuous increase in generation from renewable energy sources, marked by correlated forecast uncertainties, requires specific methodologies to support power system operators in security management. This paper proposes a probabilistic preventive control to ensure N-1 security in presence of correlated uncertainties of renewable sources and loads. By adopting a decoupled linear formulation of the AC load flow equations, the preventive control is decomposed into two subsequent linear programming problems, the former concerning the active power and the latter the voltage/reactive power-related issues. In particular, in the active control problem, the algorithm combines Third Order Polynomial Normal Transformation, Point Estimate Method, and Cornish–Fisher expansion to model the forecast uncertainties and characterize the chance constraints in the problem. The goal is to find the optimal phase shifting transformer tap setting, conventional generation redispatching, and renewable curtailment at the minimum cost to assure the probabilistic fulfillment of N and N-1 security constraints on branch active power flows. The second stage solves another linear programming problem, which aims to minimize the adjustments to generators’ set-point voltages to avoid violations at node voltages and branch-rated limits due to reactive power flows while meeting generator reactive power constraints. Simulations performed on an IEEE test system demonstrate the effectiveness of the proposed security control method in limiting the probability of violating security limits in N and N-1 state, including voltage/reactive power constraints, in presence of correlated uncertainties.

Second-Order SCA Security with almost no Fresh Randomness

Masking schemes are among the most popular countermeasures against Side-Channel Analysis (SCA) attacks. Realization of masked implementations on hardware faces several difficulties including dealing with glitches. Threshold Implementation (TI) is known as the first strategy with provable security in presence of glitches. In addition to the desired security order d, TI defines the minimum number of shares to also depend on the algebraic degree of the target function. This may lead to unaffordable implementation costs for higher orders.For example, at least five shares are required to protect the smallest nonlinear function against second-order attacks. By cuttingsuch a dependency, the successor schemes are able to achieve the same security level by just d + 1 shares, at the cost of high demand for fresh randomness, particularly at higher orders. In this work, we provide a methodology to realize the second-order glitch-extended probing-secure implementation of a group of quadratic functions with three shares and no fresh randomness. This allows us to construct second-order secure implementations of several cryptographic primitives with very limited number of fresh masks, including Keccak, SKINNY, Midori, PRESENT, and PRINCE.

A fast watermarking algorithm with enhanced security using compressive sensing and principle components and its performance analysis against a set of standard attacks

An algorithm for watermarking of digital images is proposed in this paper which utilizes Compressive Sensing (CS) with Principle Components (PCs) to achieve robustness, speed and security. CS is applied on PCs of watermark image to get the CS measurements. The singular values of these CS measurements are embedded with a scale factor into the HL subband of the cover image. The generated watermarked image contains three-layer security: one from PCs and other two from CS measurements. To recover PCs from CS measurements, a convex optimization tool, namely, the Orthogonal Matching Pursuit (OMP) is employed. Experiments are performed on both types of cover images; one with more low frequency components and another with more high frequency components. The algorithm offers state-of-the art values of robustness and security in presence of different checkmark attacks like geometrical, non-geometrical and JPEG compression. A comparison of robustness of proposed algorithm with existing algorithms reveals that the proposed algorithm outperforms for most of the noise attacks. The performance of proposed algorithm with different wavelet families (e.g., orthogonal, biorthogonal, symmetric and asymmetric) are compared in terms of robustness and execution time. Such comparison may be helpful in selecting a suitable wavelet for a class of cover images in presence of checkmark attacks. The Haar wavelet performs better for geometric noise attack whereas Bior6.8 and Sym8 for non-geometric and JPEG compression type of noise attacks. The execution time of proposed algorithm with Haar wavelet is found to be minimum for all checkmark attacks. Moreover, it is quite less as compared to Optimization based methods and close to the other watermarking technique used for H.264 video standard.

A legal information flow (LIF) scheduler based on role-based access control model

Information systems have to be consistent and secure in presence of multiple conflicting transactions. The role-based access control (RBAC) model is widely used to keep information systems consistent and secure. A role shows a job function in an enterprise and is a set of access rights (permissions). Here, a subject s is allowed to issue a method op to an object o only if an access right 〈 o, op〉 is included in the roles granted to the subject s. A subject is granted one or more than one role and issues a transaction to multiple objects. The transaction is assigned with some roles of the subject which is referred to as purpose. Even if every access request issued by every subject is authorized in the roles, illegal information flow might occur as well known confinement problem. In this paper, we define a legal information flow (LIF) relation ( R 1 ⪯ I R 2) among a pair of role families R 1 and R 2 to prevent illegal information flow. Here, an LIF relation R 1 ⪯ I R 2 shows that no illegal information flow occur if a transaction T 1 with a role family R 1 is performed prior to another transaction T 2 with a role family R 2. In addition, it is significant to discuss which transaction to be performed prior to another transaction if the both transactions manipulate the same object in a conflicting way. In this paper, we define a significantly precedent relation R 1 ⪯ s R 2 among role families R 1 and R 2 which implies that the role family R 2 is more significant than R 1. Suppose a pair of transactions T 1 and T 2 with role families R 1 and R 2 issue conflicting methods op 1 and op 2, respectively, to an object o. If R 1 ⪯ s R 2, op 2 is performed on the object o prior to op 1. The more significant a transaction is, the more prior it is performed. We discuss a legal information flow (LIF) scheduler to synchronize transactions so as to prevent illegal information flow and to serialize conflicting methods from multiple transactions in terms of significancy and information flow relation of roles families. We evaluate the LIF scheduler in terms of how much illegal information flow can be prevented compared with the other scheduler.

Improving virus protection with an efficient secure architecture with memory encryption, integrity and information leakage protection

Malicious software and other attacks are a major concern in the computing ecosystem and there is a need to go beyond the answers based on untrusted software. Trusted and secure computing can add a new hardware dimension to software protection. Several secure computing hardware architectures using memory encryption and memory integrity checkers have been proposed during the past few years to provide applications with a tamper resistant environment. Some solutions, such as HIDE, have also been proposed to solve the problem of information leakage on the address bus. We propose the CRYPTOPAGE architecture which implements memory encryption, memory integrity protection checking and information leakage protection together with a low performance penalty (3% slowdown on average) by combining the Counter Mode of operation, local authentication values and MERKLE trees. It has also several other security features such as attestation, secure storage for applications and program identification. We present some applications of the CRYPTOPAGE architecture in the computer virology field as a proof of concept of improving security in presence of viruses compared to software only solutions.