21366301
The EM Side-Channel(s)
We present results of a systematic investigation of leakage of compromising information via electromagnetic (EM) emanations from CMOS devices. These emanations are shown to consist of a multiplicity of signals, each leaking somewhat different information about the underlying computation. We show that not only can EM emanations be used to attack cryptographic devices where the power side-channel is unavailable, they can even be used to break power analysis countermeasures.
9570200
Templates as Master Keys
We introduce two new attacks: the single-bit template attack and the template-enhanced DPA attack. The single-bit template attack can be used very effectively to classify even single bits in a single side channel sample with a high probability of correctness. The template-enhanced DPA attack, combines traditional DPA with single-bit template attacks to show that if an adversary has access to a test card with even a slightly biased RNG, then he/she can break protected cryptographic implementations on a target card even if they have perfect RNGs. In support of our claim, we report results from experiments on breaking two implementations of DES and AES protected by the masking countermeasure running on smartcards of different manufacturers. 
 
In light of these results, the threat of template attacks, generally viewed as intrinsically difficult to mount, needs to be reconsidered.
14060994
On nearest neighbor indexing of nonlinear trajectories
In recent years, the problem of indexing mobile objects has assumed great importance because of its relevance to a wide variety of applications. Most previous results in this area have proposed indexing schemes for objects with linear trajectories in one or two dimensions. In this paper, we present methods for indexing objects with nonlinear trajectories. Specifically, we identify a useful condition called the convex hull property and show that any trajectory satisfying this condition can be indexed by storing a careful representation of these objects in a traditional index structure. Since a wide variety of relevant nonlinear trajectories satisfy this condition, our result significantly expands the class of trajectories for which nearest neighbor indexing schemes can be devised. We also show that even though many non-linear trajectories do not satisfy the convex hull condition, an approximate representation can often be found which satisfies it. We discuss examples of techniques which can be utilized to find representations that satisfy the convex hull property. We present empirical results to demonstrate the effectiveness of our indexing method.
15003245
Probabilistic treatment of MIXes to hamper traffic analysis
The goal of anonymity providing techniques is to preserve the privacy of users, who has communicated with whom, for how long, and from which location, by hiding traffic information. This is accomplished by organizing additional traffic to conceal particular communication relationships and by embedding the sender and receiver of a message in their respective anonymity sets. If the number of overall participants is greater than the size of the anonymity set and if the anonymity set changes with time due to unsynchronized participants, then the anonymity technique becomes prone to traffic analysis attacks. We are interested in the statistical properties of the disclosure attack, a newly suggested traffic analysis attack on the MIXes. Our goal is to provide analytical estimates of the number of observations required by the disclosure attack and to identify fundamental (but avoidable) 'weak operational modes' of the MIXes and thus to protect users against a traffic analysis by the disclosure attack.
7357174
On the design and quantification of privacy preserving data mining algorithms
The increasing ability to track and collect large amounts of data with the use of current hardware technology has lead to an interest in the development of data mining algorithms which preserve user privacy. A recently proposed technique addresses the issue of privacy preservation by perturbing the data and reconstructing distributions at an aggregate level in order to perform the mining. This method is able to retain privacy while accessing the information implicit in the original attributes. The distribution reconstruction process naturally leads to some loss of information which is acceptable in many practical situations. This paper discusses an Expectation Maximization (EM) algorithm for distribution reconstruction which is more effective than the currently available method in terms of the level of information loss. Specifically, we prove that the EM algorithm converges to the maximum likelihood estimate of the original distribution based on the perturbed data. We show that when a large amount of data is available, the EM algorithm provides robust estimates of the original distribution. We propose metrics for quantification and measurement of privacy-preserving data mining algorithms. Thus, this paper provides the foundations for measurement of the effectiveness of privacy preserving data mining algorithms. Our privacy metrics illustrate some interesting results on the relative effectiveness of different perturbing distributions.
45546568
Multi-channel Attacks
We introduce multi-channel attacks, i.e., side-channel attacks which utilize multiple side-channels such as power and EM simultaneously. We propose an adversarial model which combines a CMOS leakage model and the maximum-likelihood principle for performing and analyzing such attacks. This model is essential for deriving the optimal and very often counter-intuitive techniques for channel selection and data analysis. We show that using multiple channels is better for template attacks by experimentally showing a three-fold reduction in the error probability. Developing sound countermeasures against multi-channel attacks requires a rigorous leakage assessment methodology. Under suitable assumptions and approximations, our model also yields a practical assessment methodology for net information leakage from the power and all available EM channels in constrained devices such as chip-cards. Classical DPA/DEMA style attacks assume an adversary weaker than that of our model. For this adversary, we apply the maximum-likelihood principle to such design new and more efficient single and multiple-channel DPA/DEMA attacks.
16637841
Performance evaluation of medium access control for multiple-beam antenna nodes in a wireless LAN
We consider the medium access control (MAC) protocol design for nodes in a wireless LAN that use a wide-azimuth switched beam smart antenna system comprised of a multiple beam antenna array. The one-hop performance of carrier sense multiple access (CSMA) as well as slotted aloha for such a system is presented analytically and through simulation. The problem of synchronization of multiple beams in CSMA is investigated in our analysis. Our results show that, under heavy offered load conditions, CSMA is a good choice with nodes that have multiple-beam smart antennas, despite the performance loss due to the beam synchronization, providing a stable throughput that approaches unity and is invariant to fluctuations in the offered load. Slotted Aloha, on the other hand, is capable of higher peak throughput in a narrow range of offered loads as more switched beams are employed, but performance drastically reduces beyond optimum offered loads. We also introduce a method, expanded receive rule (ERR), whereby the tight synchronization among different beams of a receiver node in CSMA is relaxed, which is observed to provide better throughput. Finally, we also present performance results for a 4-way-handshake-type carrier sense mechanism using multiple beam antennas.
12993949
High-Speed Arithmetic Arrays
High-speed multifunction arithmetic arrays for multiplication, division, square and square-root operations are presented in this paper. These arrays seem attractive due to their versatility and speed. A recently described quotient-bit evaluation technique that uses the carry-save method in a nonuniform division array is extended here for the restoring-division process. This array includes the multiplication process as well, and the division time approaches that of multiplication. The design objective of multifunctional arithmetic arrays precludes consideration of other high-speed division techniques. A further extension of the restoring division process is shown to make the design of an array for square/square-root operation straightforward. The two underlying arrays can be coalesced to perform any one of the four operations. Possible methods of merging the arrays, with their relative merits, are also discussed. For illustration purposes, complete internal details of such a generalized pipelined array for 4-bit operation is included in this paper. Due consideration is also given to the possibility of large-scale integration of the different arrays illustrated in this paper.
9699345
Signed Modified Reflected Binary Code
A signed modified reflected binary (SMRB) code with unique representability of both positive and negative numbers has been proposed in this correspondence. The bit pattern in this code can be defined in a systematic way leading to a simple synchronous up/down counter. Some arithmetic operations for this code have also been considered.
7194636
Jigsaw-based secure data transfer over computer networks
In this paper, we present a novel encryption-less algorithm to enhance security in transmission of data in networks. The algorithm uses an intuitively simple idea of a "jigsaw puzzle" to break the transformed data into multiple parts where these parts form the pieces of the puzzle. Then these parts are packaged into packets and sent to the receiver. A secure and efficient mechanism is provided to convey the information that is necessary for obtaining the original data at the receiver-end from its parts in the packets, that is, for solving the "jigsaw puzzle". The algorithm is designed to provide information-theoretic (that is, unconditional) security by the use of a one-time pad like scheme so that no intermediate or unintended node can obtain the entire data. An authentication code is also used to ensure authenticity of every packet.
206414100
Parameters for System Effectiveness Evaluation of Distributed Systems
In a Distributed Computing System (DCS), the failure of one or more system components causes the degradation in its effectiveness to complete a given task as opposed to a complete network breakdown. This paper addresses the issue of degraded system effectiveness evaluation by introducing two static measures, namely, Distributed Program Performance Index (DPPI) and Distributed System Performance Index (DSPI). These metrics can be used to compare networks with different features for application execution. It can be used to determine if the network with high reliability and low capacity, or low reliability and high capacity is better for a given program execution. An algorithm is also developed for computing these indices, and it is shown to be not only efficient, but general enough to compute many other existing measures such as computer networks, distributed systems, transaction based systems, etc.