The distributed coordination function (DCF) in the upcoming standard for wireless LANs IEEE 802.11 is based on a CSMA/CA like access protocol. The collision avoidance part applies a rotating backoff window mechanism, that causes unequal collision probability distribution depending on the position of the selected slot within the contention window. We present simple modifications for the backoff ...

We propose a Wald Sequential Probability Ratio Test for analysis of commonly available predictions associated with spacecraft conjunctions. Such predictions generally consist of a relative state and relative state error covariance at the time of closest approach, under the assumption that prediction errors are Gaussian. We show that under these circumstances, the likelihood ratio of the Wald te...

Most of the attacks against (reduced) SHA-2 family in literature have used local collisions which are valid for linearized version of SHA-2 hash functions. Recently, at FSE ’08, an attack against reduced round SHA-256 was presented by Nikolić and Biryukov which used a local collision which is valid for the actual SHA-256 function. It is a 9-step local collision which starts by introducing a mod...

In this paper we compute the coliision probability of CBC-MAC [3] for suitably chosen messages. We show that the probability is Ω(`q/N) where ` is the number of message block, N is the size of the domain and q is the total number of queries. For random oracle the probability is O(q/N). This improved collision prbability will help us to have an efficient distinguishing attack and MAC-forgery att...

We present a fast, analytical method for estimating the probability of collision of a motion plan for a mobile robot operating under the assumptions of Gaussian motion and sensing uncertainty. Estimating the probability of collision is an integral step in many algorithms for motion planning under uncertainty and is crucial for characterizing the safety of motion plans. Our method computes an ac...

In this paper, the authors introduced a new approach to find the optimal collision avoidance maneuver considering multi threatening objects within short period, while minimizing the fuel consumption and satisfying the acceptable collision probability. A preliminary effort in applying a genetic algorithm (GA) to those kinds of problems has also been demonstrated through a simulation study with a...

The features of transmissions in underwater sensor networks (UWSNs) include lower transmission rate, longer delay time, and higher power consumption when compared with terrestrial radio transmissions. The negative effects of transmission collisions deteriorate in such environments. Existing UWSN routing protocols do not consider the transmission collision probability differences resulting from ...

Cryptographic unkeyed hash functions should satisfy preimage resistance, second-preimage resistance and collision resistance. In this article, weak second-preimage resistance and weak collision resistance are defined following the definition of weak one-wayness. Preimage resistance is one-wayness of cryptographic hash functions. The properties of weak collision resistance is discussed in this a...

Message Authentication Codes (MAC) are used to ensure the integrity of digital content is not compromised and to authenticate the sender. A MAC can be constructed by using a message digest and a shared secret value. Two different digital contents should have a low probability of having the same message digest. This is called a collision. Also, when a message digest is used to create a MAC, it s...

A set of positive generators S ⊂ N with a probability distribution p on S induces a monotone transitive walk on the integers Z, with P(x, x+s) = p(s). Kruskal’s principle observes that when two independent copies of the walk are started from nearby states then, with high probability, they do not have to travel far before visiting a common state (“collision distance”). We develop tools for deter...