Message Authentication Codes (MACs) used in today's wireless communication standards may not be able to satisfy resource limitations of simpler 5G radio types and use cases such as machine type communications. As a possible solution, we present a lightweight message authentication scheme based on the cyclic redundancy check (CRC). It has been previously shown that a CRC with an irreducible generator polynomial as the key is an ϵ-almost XOR-universal (AXU) hash function with ϵ = (m + n)/2n-1, where m is the message size and n is the CRC size. While the computation of n-bit CRCs can be efficiently implemented in hardware using linear feedback shift registers, generating random degree-n irreducible polynomials is computationally expensive for large n. We propose using a product of k irreducible polynomials whose degrees sum up to n as a generator polynomial for an n-bit CRC and show that the resulting hash functions are ϵ-AXU with ϵ = (m + n)k/2n-k. The presented message authentication scheme can be seen as providing a trade-off between security and implementation efficiency.

A central component of managing risks in cloud computing is to understand the nature of security threats. The relevance of security concerns are evidenced by the efforts from both the academic community and technological organizations such as NIST, ENISA and CSA, to investigate security threats and vulnerabilities related to cloud systems. Provisioning secure virtual networks (SVNs) in a multi-tenant environment is a fundamental aspect to ensure trust in public cloud systems and to encourage their adoption. However, comparing existing SVN-oriented solutions is a difficult task due to the lack of studies summarizing the main concerns of network virtualization and providing a comprehensive list of threats those solutions should cover. To address this issue, this paper presents a threat classification for cloud networking, describing threat categories and attack scenarios that should be taken into account when designing, comparing, or categorizing solutions. The classification is based o n the CSA threat report, building upon studies and surveys from the specialized literature to extend the CSA list of threats and to allow a more detailed analysis of cloud network virtualization issues.

Security is one of the most imperative requirements for the success of systems that deal with highly sensitive data, such as medical information. However, many existing mobile health solutions focused on collecting patients' data at their homes that do not include security among their main requirements. Aiming to tackle this issue, this paper presents SecourHealth, a lightweight security framework focused on highly sensitive data collection applications. SecourHealth provides many security services for both stored and in-transit data, displaying interesting features such as tolerance to lack of connectivity (a common issue when promoting health in remote locations) and the ability to protect data even if the device is lost/stolen or shared by different data collection agents. Together with the system's description and analysis, we also show how SecourHealth can be integrated into a real data collection solution currently deployed in the city of Sao Paulo, Brazil.

Cryptographic methods are used to protect confidential information against unauthorised modification or disclo-sure. Cryptographic algorithms providing high assurance exist, e.g. AES. However, many open problems related to assuring security of a hardware implementation of a cryptographic algorithm remain. Security of a hardware implementation can be compromised by a random fault or a deliberate attack. The traditional testing methods are good at detecting random faults, but they do not provide adequate protection against malicious alterations of a circuit known as hardware Trojans. For example, a recent attack on Intel's Ivy Bridge processor demonstrated that the traditional Logic Built-In Self-Test (LBIST) may fail even the simple case of stuck-at fault type of Trojans. In this paper, we present a novel LBIST method for Feedback Shift Register (FSR)-based cryptographic systems which can detect such Trojans. The specific properties of FSR-based cryptographic systems allow us to reach 100% single stuck-at fault coverage with a small set of deterministic tests. The test execution time of the proposed method is at least two orders of magnitude shorter than the one of the pseudo-random pattern-based LBIST. Our results enable an efficient protection of FSR-based cryptographic systems from random and malicious stuck-at faults.

The development of cloud computing services is speeding up the rate in which the organizations outsource their computational services or sell their idle computational resources. Even though migrating to the cloud remains a tempting trend from a financial perspective, there are several other aspects that must be taken into account by companies before they decide to do so. One of the most important aspect refers to security: while some cloud computing security issues are inherited from the solutions adopted to create such services, many new security questions that are particular to these solutions also arise, including those related to how the services are organized and which kind of service/data can be placed in the cloud. Aiming to give a better understanding of this complex scenario, in this article we identify and classify the main security concerns and solutions in cloud computing, and propose a taxonomy of security in cloud computing, giving an overview of the current status of security in this emerging technology.

Security is an important concern in any modern network. This also applies to Wireless Sensor Networks (WSNs), especially those used in applications that monitor sensitive information (e.g., health care applications). However, the highly constrained nature of sensors impose a difficult challenge: their reduced availability of memory, processing power and energy hinders the deployment of many modern cryptographic algorithms considered secure. For this reason, the choice of the most memory-, processing- and energy-efficient security solutions is of vital importance in WSNs. To date, several authors have developed extensive analyses comparing different encryption algorithms and key management schemes, while very little attention has been given to message authentication mechanisms. In this paper, we address this issues by identifying Authenticated Encryption with Associated Data (AEAD) schemes suitable for WSNs and by evaluating their features and performance on TelosB sensor nodes. As a result of this analysis, we identify the recommended choices depending on the characteristics of the target network.

Wireless Sensor Networks (WSNs) are a valuable technology to support countless applications in different areas. Given the WSN nodes resource constrained characteristics, designing energy-aware applications, communication protocols and security mechanisms are critical. The operating system (OS) running on the WSN node also interferes with the node overall behavior, and its energy consumption. In this paper, we develop a comparison between two different operating systems (Contiki and TinyOS) running on the same hardware platform (Crossbow TelosB). Using a set of tasks, which includes sensing, communication and security mechanisms, we evaluate their behavior in terms of energy consumption and execution time.

As TV consumers expect a growing quantity and quality of services provided to them, and providers fear uncontrolled distribution of the digital content, one of the more promising theoretical proposals to balance these two needs are the so-called "Authorized Domains" (AD). We present in this paper a novel architecture that builds on the AD concept, but extends it to allow for a more generic, open, and flexible solution. The contributions of our work are twofold: First, we analyze and motivate which features a generic and flexible IPTV architecture should exhibit in order to enable various business models, while maintaining in all instances the above-mentioned core features. Second, we present our architecture – “Personal Home Domains” (PHD) –, which adds some key features to the original AD: it allows offline content in addition to streaming; it harmonizes the distribution inside the domain with (new) the delivery from service provider to the domain; it allows for the distribution of free or age-protected content; it emphasizes the mobility of users more than the original concept; and it allows for non-compliant devices inside the domain devices as well.

Mobility, usability and security are major requirements for any Ad Hoc network systems, and there have been numerous papers in regards to them. However, often these requirements are addressed separately. For a valid solution, these requirements must be considered from an integrated view. In this paper, taking into account mobility and usability, we implement a framework which allows to securely share resources and services between devices in Ad-hoc networks, based on security policies defined by the owners of those devices. In addition, we extend our framework to support inter-domain sharing of services and resources. We detail our design, present the preliminary results of our prototype, and discuss the lessons learned, in particular how user experience led to several re-designs of the initial security solution.

We study the security of individual bits in an RSA encrypted message E N ( x ). We show that given E N ( x ), predicting any single bit in x with only a nonnegligible advantage over the trivial guessing strategy, is (through a polynomial-time reduction) as hard as breaking RSA. Moreover, we prove that blocks of O (log log N ) bits of x are computationally indistinguishable from random bits. The results carry over to the Rabin encryption scheme.Considering the discrete exponentiation function g x modulo p , with probability 1 − o (1) over random choices of the prime p , the analog results are demonstrated. The results do not rely on group representation, and therefore applies to general cyclic groups as well. Finally, we prove that the bits of ax + b modulo p give hard core predicates for any one-way function f .All our results follow from a general result on the chosen multiplier hidden number problem: given an integer N , and access to an algorithm P x that on input a random a ∈ Z N , returns a guess of the i th bit of ax mod N , recover x . We show that for any i , if P x has at least a nonnegligible advantage in predicting the i th bit, we either recover x , or, obtain a nontrivial factor of N in polynomial time. The result also extends to prove the results about simultaneous security of blocks of O (log log N ) bits.

We explore the problem of transforming n independent and identically biased {-1,1}-valued random variables X/sub 1/,...,X/sub n/ into a single {-1,1} random variable f(X/sub 1/,...,X/sub n/), so that this result is as unbiased as possible. In general, no function f produces a completely unbiased result. We perform the first study of the relationship between the bias b of these X/sub i/ and the rate at which f(X/sub 1/,...,X/sub n/) can converge to an unbiased {-1,1} random variable (as n/spl rarr//spl infin/). A {-1,1} random variable has bias b if E(X/sub i/)=b. Fixing a bias b, we explore the rate at which the output bias |E(f(X/sub 1/,...,X/sub n/))| can tend to zero for a function f:{-1,1}*/spl rarr/{-1,1}. This is accomplished by classifying the behavior of the natural normalized quantity /spl Xi/(b)/spl Delta/inf/sub f/[lim/sub n/spl rarr//spl infin//n/spl radic/(|E(f(X/sub 1/,...,X/sub n/))|] this infimum taken over all such f. We show that for rational b, /spl Xi/(b)=(1/s), where (1+b/2)=(r/s) (r and s relatively prime). Developing the theory of uniform distribution of sequences to suit our problem, we then explore the case where b is irrational. We prove a new metrical theorem concerning multidimensional Diophantine approximation type from which we show that for (Lebesgue) almost all biases b, /spl Xi/(b)=0. Finally, we show that algebraic biases exhibit curious "boundary" behavior, falling into two classes. Class 1. Those algebraics b for which /spl Xi/(b)>0 and, furthermore, c/sub 1//spl les//spl Xi/(b)/spl les/c/sub 2/ where c/sub 1/ and c/sub 2/ are positive constants depending only on b's algebraic characteristics. Class 2. Those algebraics b for which there exist n>0 and f: {-1,1}/sup n//spl rarr/{-1,1} so that E(f(X/sub 1/,...,X/sub n/))=0. Notice that this classification excludes the possibility that n/spl radic/(|E(f(X/sub 1/,...,X/sub n/))| limits to zero (for algebraics). For rational and algebraic biases, we also study the computational problem by restricting f to be a polynomial time computable function. Finally, we discuss natural extensions where output distributions other than the uniform distribution on {-1,1} are sought.

We study the security of individual bits in an RSA encrypted message E/sub N/(X). We show that given E/sub N/(X), predicting any single bit in x with only a non-negligible advantage over the trivial guessing strategy is (through a polynomial time reduction) as hard as breaking RSA. We briefly discuss a related result for bit security of the discrete logarithm.