The ability to recover quickly from large-impact, hard-to-predict, and rare incidents without incurring sizable permanent damage is vital to major stakeholders in ICT infrastructures of national importance.

Traditional risk assessment methods underestimate the risks of large-impact, hard-to-predict, and rare events in information systems. An alternative approach extends these methods to better evaluate risks associated with black and gray swans.

In Norway, BankID is the banking industry's public-key infrastructure (PKI) of choice for authenticating Internet customers. But do BanklD's differences from standard PKIs make it a riskier choice? This assessment, based on both publicly available information and usage experiences, addresses that question.

Open wireless networks raise privacy issues and entail increased risk of malicious attacks and illegal downloading activities. Such networks are nonetheless attractive-particularly to universities-because they enhance usability and thus expand access to nonsensitive system resources. At universities, such access brings numerous benefits to students, faculty, and the surrounding community alike. Here, the authors describe the challenges of removing individual user authentication requirements at the perimeter of a university network in which mobile device users access system resources over wireless links to the wired infrastructure. The authors discuss how to mitigate the security and privacy risks entailed in an open network of this sort, and also describe how IT departments can vary the network's degree of openness.

Wi-Fi networks, based on the IEEE 802.11 b/g standards, have become very popular in recent years. Many users have installed Wi-Fi networks at home, and numerous corporations have added Wi-Fi access points to their wired networks, giving employees easier access to corporate data and services. Hackers can decrypt and read data on a wireless link protected by built-in WEP encryption, and may even be able to access the data on a wired network through a Wi-Fi access point. We assess Wi-Fi network security in one city, analyze alternative security techniques, and suggest ways to secure such networks.

A performance analysis of an adaptive modulation (ACM) system operating on a multiple-input multiple-output (MIMO) channel with uncorrelated Rayleigh fading subchannels is presented. Rate adaptation is based on periodically transmitted channel state information (CSI) back to the transmitter, providing information about the channel signal-to-noise ratio (CSNR) as predicted by the receiver. Transmit diversity is utilized by employing space-time block coding (STBC) at the transmitter.

Punctured convolutional codes with good performance are reported for rates ( n -1)/ n  with  n =5, 6, 7, 8 and constraint lengths  k =2, 3, . . ., 6. The tabulated codes are nonsystematic binary convolutional codes with maximum free distance and minimum information weight, for use with soft-decision Viterbi decoding

Communication systems and storage systems derive symbol synchronization from the received symbol stream. To facilitate symbol synchronization, the channel sequences must have a short maximum zero-run length. One way to achieve this is to use a coset of an (n, k) convolutional code to generate the channel inputs. For k⩽n-2, it is shown that there exist cosets with short maximum zero-run length for any constraint length. Any coset of an (n, n-1) code with high rate and/or large constraint length is shown to have a large maximum zero-run length. A systematic procedure for obtaining cosets with short maximum zero-run length from (n, k) codes is presented, and new cosets with short maximum zero-run length and large minimum Hamming distance are tabulated

A coset of a convolutional code may be used to generate a zero-run length limited trellis code for a 1-D partial-response channel. The free squared Euclidean distance, dfree2, at the channel output is lower bounded by the free Hamming distance of the convolutional code. The lower bound suggests the use of a convolutional code with maximal free Hamming distance, dmax(R,N), for given rate R and number of decoder states N. In this paper we present cosets of convolutional codes that generate trellis codes with dfree 2>dmax(R,N) for rates 1/5⩽R⩽7/9 and (d free2=dmax(R,N) for R=13/16,29/32,61/64, The tabulated convolutional codes with R⩽7/9 were not optimized for Hamming distance. Instead, a computer search was used to determine cosets of convolutional codes that exploit the memory of the 1-D channel to increase dfree2 at the channel output. The search was limited by only considering cosets with certain structural properties. The R⩾13/16 codes were obtained using a new construction technique for convolutional codes with free Hamming distance 4. Newly developed bounds on the maximum zero-run lengths of cosets were used to ensure a short maximum run length at the 1-D channel output

A coded (1-D) system containing a punctured convolutional encoder is analyzed. In general, a punctured encoder with 2v states results in a decoder trellis with 2v+1 states and a periodically time-varying branch structure. A class C of punctured convolutional encoders for which the decoder trellis has a fixed branch structure with 2v states is described. An encoder in this class can be combined with a precoder to form a new punctured convolutional encoder that generates the output from the precoder. The author determines the set of good variable-rate trellis codes for selectable rate encoding and Viterbi decoding. A set of variable-rate trellis codes is generated by a variable-rate punctured convolutional encoder in C. The author also determines punctured convolutional encoders in C that generate a single good high-rate trellis code.