Publications
Journal Article
A thousand brains: toward biologically constrained AI
SN Applied Sciences 3 (2021): 743.Status: Published
A thousand brains: toward biologically constrained AI
This paper reviews the state of artificial intelligence (AI) and the quest to create general AI with human-like cognitive capabilities. Although existing AI methods have produced powerful applications that outperform humans in specific bounded domains, these techniques have fundamental limitations that hinder the creation of general intelligent systems. In parallel, over the last few decades, an explosion of experimental techniques in neuroscience has significantly increased our understanding of the human brain. This review argues that improvements in current AI using mathematical or logical techniques are unlikely to lead to general AI. Instead, the AI community should incorporate neuroscience discoveries about the neocortex, the human brain’s center of intelligence. The article explains the limitations of current AI techniques. It then focuses on the biologically constrained Thousand Brains Theory describing the neocortex’s computational principles. Future AI systems can incorporate these principles to overcome the stated limitations of current systems. Finally, the article concludes that AI researchers and neuroscientists should work together on specified topics to achieve biologically constrained AI with human-like capabilities.
Afilliation | Machine Learning |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2021 |
Journal | SN Applied Sciences |
Volume | 3 |
Number | 8 |
Pagination | 743 |
Date Published | 07/2021 |
Publisher | Springer nature |
Keywords | Biologically constrained general AI, Common cortical algorithm, General AI, Limitations of narrow AI, Neocortex, Neuroscience |
DOI | 10.1007/s42452-021-04715-0 |
Tutorial on systems with antifragility to downtime
Computing 104 (2021): 73-93.Status: Published
Tutorial on systems with antifragility to downtime
An antifragile system of software and stakeholders, including designers, developers, and operators, learn from incidents how to avoid outages and maintain high uptime. This tutorial article reviews how to design and operate such socio-technical systems with antifragility to downtime. It documents the importance of four design principles and two operational principles by exploring the polar opposite anti-principles and the interplay between the principles and the anti-principles. The design principles mandate a software design of separate and isolatable processes with sufficient diversity and redundancy. The processes should communicate asynchronously over an external network. The operational principles imply that the software development teams should repeatedly inject artificial failures into the production system to understand its behavior and detect and mitigate vulnerabilities as the system and its environment change.
Afilliation | Cryptography |
Project(s) | No Simula project |
Publication Type | Journal Article |
Year of Publication | 2021 |
Journal | Computing |
Volume | 104 |
Number | 1 |
Pagination | 73-93 |
Date Published | 01/2021 |
Publisher | Springer |
Keywords | Antifragility, Design principles, Distributed systems, Uptime |
DOI | 10.1007/s00607-020-00895-6 |
Journal Article
Biologically driven AI
IEEE Computer 52, no. 8 (2019): 72-87.Status: Published
Biologically driven AI
Afilliation | Cryptography |
Publication Type | Journal Article |
Year of Publication | 2019 |
Journal | IEEE Computer |
Volume | 52 |
Issue | 8 |
Pagination | 72-87 |
Publisher | IEEE |
Dominating software systems
IEEE Software 36, no. 4 (2019): 81-87.Status: Published
Dominating software systems
Afilliation | Cryptography |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2019 |
Journal | IEEE Software |
Volume | 36 |
Issue | 4 |
Pagination | 81-87 |
Publisher | IEEE |
Software systems with antifragility to downtime
IEEE Computer 52, no. 2 (2019): 23-31.Status: Published
Software systems with antifragility to downtime
Afilliation | Cryptography |
Publication Type | Journal Article |
Year of Publication | 2019 |
Journal | IEEE Computer |
Volume | 52 |
Issue | 2 |
Pagination | 23-31 |
Publisher | IEEE |
Book
Anti-fragile ICT Systems
Vol. 1. Switzerland: Springer International Publishing, 2016.Status: Published
Anti-fragile ICT Systems
The book introduces a novel approach to the design and operation of large ICT systems. It views the technical solutions and their stakeholders as complex adaptive systems and argues that traditional risk analyses cannot predict all future incidents with major impacts. To avoid unacceptable events, it is necessary to establish and operate anti-fragile ICT systems that limit the impact of all incidents, and which learn from small-impact incidents how to function increasingly well in changing environments.
The book applies four design principles and one operational principle to achieve anti-fragility for different classes of incidents. It discusses how systems can achieve high availability, prevent malware epidemics, and detect anomalies. Analyses of Netflix’s media streaming solution, Norwegian telecom infrastructures, e-government platforms, and Numenta’s anomaly detection software show that cloud computing is essential to achieving anti-fragility for classes of events with negative impacts.
Afilliation | Communication Systems |
Project(s) | Simula UiB |
Publication Type | Book |
Year of Publication | 2016 |
Volume | 1 |
Edition | 1 |
Number of Pages | 151 |
Publisher | Springer International Publishing |
Place Published | Switzerland |
URL | http://link.springer.com/book/10.1007/978-3-319-30070-2 |
DOI | 10.1007/978-3-319-30070-2 |
Journal Article
Building trust in e-government services
IEEE Computer 49, no. 1 (2016): 66-74.Status: Published
Building trust in e-government services
Afilliation | Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2016 |
Journal | IEEE Computer |
Volume | 49 |
Issue | 1 |
Pagination | 66-74 |
Date Published | 01/2016 |
Publisher | IEEE |
ISSN | 0018-9162 |
Keywords | Cloud cmputing, Electronic government, Iterative methods, Trust management, User centered design |
DOI | 10.1109/MC.2016.4 |
Vendor malware: detection limits and mitigation
IEEE Computer 49, no. 8 (2016): 62-69.Status: Published
Vendor malware: detection limits and mitigation
Computing device vendors can introduce malware that is nearly impossible to detect with known methods, but microservice solutions can limit the negative impact. Malware contains instructions whose execution negatively impacts stakeholders, typically leading to unauthorized access and computation, data theft, loss of privacy, inability to inspect data, or prolonged downtime. A computing system's robustness to malware attacks strongly depends on the ability of the technical system and its stakeholders to either detect inactive malware before it executes or to detect active executing malware as soon as possible, before it causes serious damage. Many previous works discuss the general difficulty of detecting malware, but we focus on the ability of buyers and other legitimate stakeholders to detect malware inserted in computing devices by vendors and other insiders with access to the devices before they reach the buyers.
Afilliation | Communication Systems |
Publication Type | Journal Article |
Year of Publication | 2016 |
Journal | IEEE Computer |
Volume | 49 |
Issue | 8 |
Pagination | 62-69 |
Date Published | 08/2016 |
Publisher | IEEE |
ISSN | 0018-9162 |
Keywords | Computer architecture, Computer crime, Computer security, Malware, Software Engineering, Supply chain management |
DOI | 10.1109/MC.2016.227 |
Journal Article
Diversity Reduces the Impact of Malware
IEEE Security & Privacy 13, no. 3 (2015): 48-54.Status: Published
Diversity Reduces the Impact of Malware
Many Internet networks have limited internal diversity, making them vulnerable to serious malware spreading. A proposed malware-halting technique that uses software diversity can halt infectious outbreaks on these networks.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2015 |
Journal | IEEE Security & Privacy |
Volume | 13 |
Issue | 3 |
Pagination | 48-54 |
Publisher | IEEE |
Other Numbers | DOI: 10.1109/MSP.2013.48 |
Keywords | infectious outbreaks, internal diversity, Internet networks, malware-halting technique, serious malware spreading, software diversity |
Toward anti-fragility: a malware-halting technique
IEEE Security & Privacy 13, no. 4 (2015): 40-46.Status: Published
Toward anti-fragility: a malware-halting technique
Afilliation | Cryptography |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2015 |
Journal | IEEE Security & Privacy |
Volume | 13 |
Issue | 4 |
Pagination | 40-46 |
Publisher | IEEE |
Toward anti-fragility: a malware-halting technique
IEEE Security & Privacy 13, no. 3 (2015): 48-54.Status: Published
Toward anti-fragility: a malware-halting technique
Afilliation | Cryptography |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2015 |
Journal | IEEE Security & Privacy |
Volume | 13 |
Issue | 3 |
Pagination | 48-54 |
Publisher | IEEE |
Toward Anti-fragility: A Malware-Halting Technique
IEEE Security & Privacy 13, no. 4 (2015): 40-46.Status: Published
Toward Anti-fragility: A Malware-Halting Technique
Unlike robust systems, anti-fragile systems learn to adapt to changes and reduce the impact of future incidents. A combination of software diversity and imperfect malware detection can help achieve networked computing systems that are anti-fragile to malware with unknown and time-varying spreading mechanisms.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2015 |
Journal | IEEE Security & Privacy |
Volume | 13 |
Issue | 4 |
Pagination | 40-46 |
Publisher | IEEE |
Other Numbers | DOI: 10.1109/MSP.2015.73 |
Keywords | anti fragile systems, anti fragility, imperfect malware detection, malware-halting technique, networked computing systems |
Public outreach
Dømt til dårlig sikkerhet
In Chronicle in Bergens Tidende. Bergen: Bergens Tidende, 2014.Status: Published
Dømt til dårlig sikkerhet
SIKKERHET PÅ NETT: Ville vi akseptert at postmannen åpnet alle brevene våre og la innholdet i postkassen?
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2014 |
Secondary Title | Chronicle in Bergens Tidende |
Date Published | 02/2014 |
Publisher | Bergens Tidende |
Place Published | Bergen |
Type of Work | Chronicle |
URL | http://www.bt.no/meninger/kronikk/Domt-til-darlig-sikkerhet-3055677.html |
Talks, invited
Hva kan gjøres når man ikke stoler på de som lager utstyret til Ekom-nettet vårt?
In Justisdepartementet. Kriserådet, 2014.Status: Published
Hva kan gjøres når man ikke stoler på de som lager utstyret til Ekom-nettet vårt?
Afilliation | , Communication Systems, Communication Systems |
Project(s) | The Center for Resilient Networks and Applications |
Publication Type | Talks, invited |
Year of Publication | 2014 |
Location of Talk | Justisdepartementet |
Publisher | Kriserådet |
Journal Article
Management of hidden risks
IEEE Computer 46, no. 1 (2013): 65-70.Status: Published
Management of hidden risks
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2013 |
Journal | IEEE Computer |
Volume | 46 |
Issue | 1 |
Pagination | 65-70 |
Publisher | IEEE |
Keywords | Adaptive systems, Base stations, Electronic voting, information systems, Mobile handsets, Privacy, risk management, Security |
DOI | 10.1109/MC.2012.397 |
Journal Article
Building and Maintaining Trust in Internet Voting
IEEE Computer 45, no. 5 (2012): 74-80.Status: Published
Building and Maintaining Trust in Internet Voting
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2012 |
Journal | IEEE Computer |
Volume | 45 |
Issue | 5 |
Pagination | 74-80 |
Publisher | IEEE |
Other Numbers | DOI: 10.1109/MC.2012.35 |
Keywords | data privacy, government data processing, Internet computer forensics, risk analysis |
Toward a Practical Technique to Halt Multiple Virus Outbreaks on Computer Networks
Journal of Computer Networks and Communications 2012 (2012).Status: Published
Toward a Practical Technique to Halt Multiple Virus Outbreaks on Computer Networks
The author analyzes a technique to prevent multiple simultaneous virus epidemics on any vulnerable computer network with inhomogeneous topology. The technique immunizes a small fraction of the computers and utilizes diverse software platforms to halt the virus outbreaks. The halting technique is of practical interest since a network's detailed topology need not be known.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2012 |
Journal | Journal of Computer Networks and Communications |
Volume | 2012 |
Publisher | Hindawi Publishing Corporation |
DOI | 10.1155/2012/462747 |
Public outreach
Helseopplysninger på nett
In Letter to there editor in Dagens Næringsliv, 2012.Status: Published
Helseopplysninger på nett
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2012 |
Secondary Title | Letter to there editor in Dagens Næringsliv |
Date Published | 05/2012 |
Nytt sårbarhetsutvalg må til
In Feature article in Dagens Næringsliv, 2012.Status: Published
Nytt sårbarhetsutvalg må til
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2012 |
Secondary Title | Feature article in Dagens Næringsliv |
Date Published | 03/2012 |
Public outreach
Farene ved e-valg
In Feature article in Dagbladet, 2011.Status: Published
Farene ved e-valg
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2011 |
Secondary Title | Feature article in Dagbladet |
Date Published | 09/2011 |
Systemene vil svikte
In Feature article in Dagens Næringsliv, 2011.Status: Published
Systemene vil svikte
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2011 |
Secondary Title | Feature article in Dagens Næringsliv |
Date Published | 12/2011 |
Proceedings, refereed
Security Analysis of Mobile Phones Used as OTP Generators
In International Workshop on Security Theory and Practice, WISTP 2010. Vol. 6033. Lecture Notes in Computer Science, Springer Verlag, 2010.Status: Published
Security Analysis of Mobile Phones Used as OTP Generators
The Norwegian company Encap has developed protocols enabling individuals to use their mobile phones as one-time password (OTP) generators. An initial analysis of the protocols reveals minor security flaws. System-level testing of an online bank utilizing Encap’s solution then shows that several attacks allow a malicious individual to turn his own mobile phone into an OTP generator for another individual’s bank account. Some of the suggested countermeasures to thwart the attacks are already incorporated in an updated version of the online banking system.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Proceedings, refereed |
Year of Publication | 2010 |
Conference Name | International Workshop on Security Theory and Practice, WISTP 2010 |
Volume | 6033 |
Pagination | 324-331 |
Date Published | 04/2010 |
Publisher | Lecture Notes in Computer Science, Springer Verlag |
ISBN Number | 978-3-642-12367-2 |
ISSN Number | 0302-9743 |
URL | http://link.springer.com/chapter/10.1007/978-3-642-12368-9_26 |
DOI | 10.1007/978-3-642-12368-9_26 |
Journal Article
Toward Risk Assessment of Large-Impact and Rare Events
IEEE Security & Privacy 8, no. 3 (2010): 21-27.Status: Published
Toward Risk Assessment of Large-Impact and Rare Events
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2010 |
Journal | IEEE Security & Privacy |
Volume | 8 |
Issue | 3 |
Pagination | 21-27 |
Publisher | IEEE |
Other Numbers | DOI: 10.1109/MSP.2010.55 |
Keywords | information systems, risk management |
DOI | 10.1109/MSP.2010.55 |
Journal Article
Risk Assessment of a National Security Infrastructure
IEEE Security & Privacy 7, no. 1 (2009): 34-41.Status: Published
Risk Assessment of a National Security Infrastructure
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2009 |
Journal | IEEE Security & Privacy |
Volume | 7 |
Issue | 1 |
Pagination | 34-41 |
Publisher | IEEE |
Keywords | bank data processing, Internet, public key cryptography |
DOI | 10.1109/MSP.2009.17 |
Public outreach
Alvorlige svakheter ved e-valg
In Letter to editor in Bergens Tidende, 2009.Status: Published
Alvorlige svakheter ved e-valg
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2009 |
Secondary Title | Letter to editor in Bergens Tidende |
Date Published | 05/2009 |
Når folk stemmer hjemme
In Feature article in HUBRO, 2009.Status: Published
Når folk stemmer hjemme
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Public outreach |
Year of Publication | 2009 |
Secondary Title | Feature article in HUBRO |
Proceedings, refereed
A Proof of Concept Attack against Norwegian Internet Banking Systems
In 12th International Conference on Financial Cryptography and Data Security (FC08). Vol. Volume 5143 of the series Lecture Notes in Computer Science, 2008.Status: Published
A Proof of Concept Attack against Norwegian Internet Banking Systems
The banking industry in Norway has developed a new secu- rity infrastructure for conducting commerce on the Internet. The initia- tive, called BankID, aims to become a national ID infrastructure sup- porting services such as authentication and digital signatures for the entire Norwegian population. This paper describes a practical man-in- the-middle attack against online banking applications using BankID. The attack gives an adversary access to customer bank accounts in two dif- ferent online banking systems. Proof of concept code has been developed and executed to demonstrate the seriousness of the problem.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Proceedings, refereed |
Year of Publication | 2008 |
Conference Name | 12th International Conference on Financial Cryptography and Data Security (FC08) |
Volume | Volume 5143 of the series Lecture Notes in Computer Science |
Pagination | 197-201 |
Identity Theft: Much too Easy? A study of Online Systems in Norway
In 12th International Conference on Financial Cryptography and Data Security (FC08). Vol. Volume 5143 of the series Lecture Notes in Computer Science, 2008.Status: Published
Identity Theft: Much too Easy? A study of Online Systems in Norway
Governments and commercial companies connect more and more computer systems to the Internet, giving people easier access to ser- vices. Many of these online services handle personal information. Leak- age of such information can facilitate large-scale identity theft. This paper determines how personal information leaks from online systems of national importance, discusses proof of concept software to demon- strate the seriousness of the problem, and suggests how to improve the situation.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Proceedings, refereed |
Year of Publication | 2008 |
Conference Name | 12th International Conference on Financial Cryptography and Data Security (FC08) |
Volume | Volume 5143 of the series Lecture Notes in Computer Science |
Pagination | 192-196 |
Robbing Banks with Their Own software—an Exploit against Norwegian Online Banks
In 23rd International Information Security Conference (SEC 2008). Vol. Volume 278 of the series IFIP – The International Federation for Information Processing . Springer, 2008.Status: Published
Robbing Banks with Their Own software—an Exploit against Norwegian Online Banks
The banking industry in Norway has developed a new security infrastruc- ture for conducting commerce on the Internet. The initiative, called BankID, aims to become a national ID infrastructure supporting services such as authentication and digital signatures for the entire Norwegian population. This paper describes a man-in-the-middle vulnerability in online banking applications using BankID. An exploit has been implemented and successfully run against two randomly chosen online banking systems to demonstrate the seriousness of the attack.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Proceedings, refereed |
Year of Publication | 2008 |
Conference Name | 23rd International Information Security Conference (SEC 2008) |
Volume | Volume 278 of the series IFIP – The International Federation for Information Processing |
Pagination | 63-77 |
Publisher | Springer |
Journal Article
Open Wireless Networks on University Campuses
IEEE Security & Privacy 6, no. 4 (2008): 14-20.Status: Published
Open Wireless Networks on University Campuses
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2008 |
Journal | IEEE Security & Privacy |
Volume | 6 |
Issue | 4 |
Pagination | 14-20 |
Publisher | IEEE |
Keywords | authorisation, radio networks, telecommunication security |
DOI | 10.1109/MSP.2008.92 |
Journal Article
Challenges in securing networked J2ME applications
IEEE Computer 40, no. 2 (2007): 24-30.Status: Published
Challenges in securing networked J2ME applications
An increasing number of smart phones support Java 2, Micro Edition. Mobile application developers must deal with J2ME's inherent security weaknesses as well as bugs in implementations on real devices. The new Security and Trust Services API for J2ME addresses some of these challenges, although it too has shortcomings.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2007 |
Journal | IEEE Computer |
Volume | 40 |
Issue | 2 |
Pagination | 24-30 |
Publisher | IEEE |
Keywords | application program interfaces, Java, mobile computing, security of data |
DOI | 10.1109/MC.2007.49 |
Lessons from the Norwegian ATM System
IEEE Security & Privacy 5, no. 6 (2007): 25-31.Status: Published
Lessons from the Norwegian ATM System
This case study focuses on real-world ATM card misuse, illustrating how too much secrecy led to a deterioration of PIN-based authentication procedures, and why a bank's refusal to share technical information is a threat to customers during a conflict.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2007 |
Journal | IEEE Security & Privacy |
Volume | 5 |
Issue | 6 |
Pagination | 25-31 |
Publisher | IEEE |
Keywords | automatic teller machines, message authentication |
DOI | 10.1109/MSP.2007.168 |
Vulnerabilities in E-Governments
International Journal of Electronic Security and Digital Forensics 1, no. 1 (2007): 89-100.Status: Published
Vulnerabilities in E-Governments
This paper shows that more than 80% of the E-Governments in the world are vulnerable to common Web-application attacks such as Cross Site Scripting and SQL injection. Industrialized countries were found to be more vulnerable than under-developed countries (90% vs. 50%). The paper also describes some malicious data mining possibilities on the Norwegian E-Government, and how information can be combined and used to create other practical attacks.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2007 |
Journal | International Journal of Electronic Security and Digital Forensics |
Volume | 1 |
Issue | 1 |
Pagination | 89-100 |
Publisher | InderScience Publishers |
Keywords | cross site scripting, e-government, Electronic government, electronic security, Privacy, SQL injection, vulnerabilities, web application attacks |
DOI | 10.1504/IJESDF.2007.013595 |
Journal Article
Adaptive coded modulation with receive antenna diversity and imperfect channel knowledge at receiver and transmitter
IEEE Transactions on Vehicular Technology 55, no. 2 (2006): 458-465.Status: Published
Adaptive coded modulation with receive antenna diversity and imperfect channel knowledge at receiver and transmitter
Unifying and generalizing the works of Cai and Giannakis and Oien et al., the performance of an adaptive trellis-coded modulation system where receive antenna diversity is implemented by means of maximum ratio combining is analyzed and optimized. As in the work of Cai and Giannakis, the analysis is done in the presence of both estimation and prediction errors. Rayleigh fading on each subchannel is considered, with the estimation and prediction being performed independently on each subchannel. The system optimization process is done in such a way that the throughput is maximized under a bit-error-rate (BER) constraint. The numerical example employs a Jakes-fading spectrum and shows how the power should be distributed between pilot and data symbols and how often pilot symbols should be transmitted for maximum throughput under an instantaneous (with respect to the predicted channel) BER constraint.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2006 |
Journal | IEEE Transactions on Vehicular Technology |
Volume | 55 |
Issue | 2 |
Pagination | 458 - 465 |
Publisher | IEEE |
Keywords | Adaptive systems, Bit error rate, Diversity reception, Estimation error, Modulation coding, Performance Analysis, Rayleigh channels, Receiving antennas, Throughput, Transmitters |
DOI | 10.1109/TVT.2005.863348 |
Case study: online banking security
IEEE Security & Privacy 4, no. 2 (2006): 14-20.Status: Published
Case study: online banking security
A description of attack scenarios over a two-year period illustrates several key security issues with Internet banking systems in Norway. Given the banks' security-by-obscurity policy, online customers knew little about security levels and falsely believed their assets were safe.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2006 |
Journal | IEEE Security & Privacy |
Volume | 4 |
Issue | 2 |
Pagination | 14-20 |
Publisher | IEEE |
DOI | 10.1109/MSP.2006.36 |
Journal Article
Securing Wi-Fi networks
IEEE Computer 38, no. 7 (2005): 28-34.Status: Published
Securing Wi-Fi networks
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2005 |
Journal | IEEE Computer |
Volume | 38 |
Issue | 7 |
Pagination | 28-34 |
Publisher | IEEE |
Keywords | Cities and towns, Communication system security, Computer crime, Computer hacking, Computer networks, Cryptography Data security |
DOI | 10.1109/MC.2005.241 |
Journal Article
Impact of channel prediction on adaptive coded modulation performance in Rayleigh fading
IEEE Transactions on Vehicular Technology 53, no. 3 (2004): 758-769.Status: Published
Impact of channel prediction on adaptive coded modulation performance in Rayleigh fading
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2004 |
Journal | IEEE Transactions on Vehicular Technology |
Volume | 53 |
Issue | 3 |
Pagination | 758-769 |
Publisher | IEEE |
DOI | 10.1109/TVT.2004.827156 |
Weaknesses in the temporal key hash of WPA
Mobile Computing and Communications Review 8, no. 2 (2004): 76-83.Status: Published
Weaknesses in the temporal key hash of WPA
This article describes some weaknesses in the key scheduling in Wi-Fi Protected Access (WPA) put forward to secure the IEEE standard 802.11-1999. Given a few RC4 packet keys in WPA it is possible to find the Temporal Key (TK) and the Message Integrity Check (MIC) key. This is not a practical attack on WPA, but it shows that parts of WPA are weak on their own. Using this attack it is possible to do a TK recovery attack on WPA with complexity O(2105) compared to a brute force attack with complexity O (2128).
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2004 |
Journal | Mobile Computing and Communications Review |
Volume | 8 |
Issue | 2 |
Pagination | 76-83 |
Date Published | 04/2004 |
Publisher | ACM Sigmobile |
Keywords | 802.11, MIC, Michael, temporal key hash, TKIP, WPA |
DOI | 10.1145/997122.997132 |
Proceedings, refereed
Limitations in spectral efficiency of a rate-adaptive MIMO system utilizing pilot-aided channel prediction
In The 57th IEEE Semiannual Vehicular Technology Conference, 2003 (VTC 2003-Spring). Vol. 1, 2003.Status: Published
Limitations in spectral efficiency of a rate-adaptive MIMO system utilizing pilot-aided channel prediction
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Proceedings, refereed |
Year of Publication | 2003 |
Conference Name | The 57th IEEE Semiannual Vehicular Technology Conference, 2003 (VTC 2003-Spring) |
Volume | 1 |
Pagination | 282-286 |
DOI | 10.1109/VETECS.2003.1207547 |
Journal Article
New short constraint length rate (n-1)/n punctured convolutional codes for soft-decision Viterbi decoding
IEEE Transactions on Information Theory 34, no. 5 (2002): 1079-1081.Status: Published
New short constraint length rate (n-1)/n punctured convolutional codes for soft-decision Viterbi decoding
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
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2002 |
Journal | IEEE Transactions on Information Theory |
Volume | 34 |
Issue | 5 |
Pagination | 1079-1081 |
Publisher | IEEE |
Keywords | punctured convolutional codes, soft-decision Viterbi decoding |
DOI | 10.1109/18.21236 |
Journal Article
Spectral efficiency of adaptive coded modulation in urban microcellular networks
IEEE Transactions on Vehicular Technology 50, no. 1 (2001): 205-222.Status: Published
Spectral efficiency of adaptive coded modulation in urban microcellular networks
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2001 |
Journal | IEEE Transactions on Vehicular Technology |
Volume | 50 |
Issue | 1 |
Pagination | 205-222 |
Publisher | IEEE |
Keywords | Adaptive coding, Convolutional codes, Degradation, Fading, Information rates, Intelligent networks, Interference |
DOI | 10.1109/25.917922 |
Journal Article
Adaptive multidimensional coded modulation over flat fading channels
IEEE Journal on Selected Areas in Communications (IEEE JSAC) 18, no. 7 (2000): 1153-1158.Status: Published
Adaptive multidimensional coded modulation over flat fading channels
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2000 |
Journal | IEEE Journal on Selected Areas in Communications (IEEE JSAC) |
Volume | 18 |
Issue | 7 |
Pagination | 1153-1158 |
Publisher | IEEE |
Keywords | Adaptive coding, Additive white noise, AWGN channels, Codecs, Convolutional codes, Decoding, Fading, Feedback, Modulation coding, Multidimensional systems |
DOI | 10.1109/49.857915 |
On classes of convolutional codes that are not asymptotically catastrophic
IEEE Transactions on Information Theory 46, no. 2 (2000): 663-669.Status: Published
On classes of convolutional codes that are not asymptotically catastrophic
The author denotes by w0 the minimum average weight per edge over all nonzero cycles in the state diagram for a convolutional code, and assumes that a technique is available for generating canonical parity-check matrices for codes with increasing degree m. The obtained class of codes is asymptotically catastrophic if w0 approaches zero for large m. We prove the existence of convolutional code classes that are not asymptotically catastrophic by providing explicit constructions of codes with nonzero w0 for all m
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 2000 |
Journal | IEEE Transactions on Information Theory |
Volume | 46 |
Issue | 2 |
Pagination | 663-669 |
Publisher | IEEE |
Keywords | Bit error rate, Convolutional codes |
DOI | 10.1109/18.825838 |
Journal Article
Tight bounds on the minimum average weight per branch for rate (N-1)/N convolutional codes
IEEE Transactions on Information Theory 43, no. 4 (1997): 1301-1305.Status: Published
Tight bounds on the minimum average weight per branch for rate (N-1)/N convolutional codes
Consider a cycle in the state diagram of a convolutional code. The average weight per branch of the cycle is equal to the total Hamming weight of all labels on the branches divided by the number of branches. Let w0 be the minimum average weight per branch over all cycles in the state diagram, except the zero state self-loop of weight zero. Codes with low w0 result in high bit error probabilities when they are used with either Viterbi or sequential decoding. Hemmati and Costello (1980) showed that w0 is upper-bounded by 2ν-2/(3·2ν-2-1) for a class of (2,1) codes where ν denotes the constraint length. In the present correspondence it is shown that the bound is valid for a large class of (n,n-1) codes, n⩾2. Examples of high-rate codes with w0 equal to the upper bound are also given. Hemmati and Costello defined a class of codes to be asymptotically catastrophic if w 0 approaches zero for large ν. The class of (n,n-1) codes constructed by Wyner and Ash (1963) is shown to be asymptotically catastrophic. All codes in the class have minimum possible w0 equal to 1/ν
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 1997 |
Journal | IEEE Transactions on Information Theory |
Volume | 43 |
Issue | 4 |
Pagination | 1301-1305 |
Publisher | IEEE |
Keywords | Convolutional codes, error statistics, minimisation |
DOI | 10.1109/18.605599 |
A note on asymptotically catastrophic convolutional codes of rate (n-1)/n
IEEE Transactions on Communications 45, no. 9 (1997): 1014-1016.Status: Published
A note on asymptotically catastrophic convolutional codes of rate (n-1)/n
Convolutional codes with rate R=(n-1)/n,n⩾2, are defined in terms of their minimal parity check matrices. The matrices are represented by a binary vector notation introduced by Ytrehus (1992). The upper bounds on ω0 (minimum average weight per branch) are presented. Many classes of rate (n-1)/n convolutional codes are shown to be asymptotically catastrophic
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 1997 |
Journal | IEEE Transactions on Communications |
Volume | 45 |
Issue | 9 |
Pagination | 1014-1016 |
Publisher | IEEE |
Journal Article
Cosets of convolutional codes with short maximum zero-run lengths
IEEE Transactions on Information Theory 41, no. 4 (1995): 1145-1150.Status: Published
Cosets of convolutional codes with short maximum zero-run lengths
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
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 1995 |
Journal | IEEE Transactions on Information Theory |
Volume | 41 |
Issue | 4 |
Pagination | 1145-1150 |
Publisher | IEEE |
Keywords | Convolutional codes, encoding, Error correction, Hamming distance |
Journal Article
Improved coding techniques for preceded partial-response channels
IEEE Transactions on Information Theory 40, no. 2 (1994): 482-493.Status: Published
Improved coding techniques for preceded partial-response channels
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
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 1994 |
Journal | IEEE Transactions on Information Theory |
Volume | 40 |
Issue | 2 |
Pagination | 482 - 493 |
Publisher | IEEE |
Keywords | Convolutional codes, encoding, telecommunication channels, trellis codes |
DOI | 10.1109/18.312170 |
Journal Article
Punctured convolutional codes for the 1-D partial-response channel
IEEE Transactions on Information Theory 37, no. 3 (1991): 808-817.Status: Published
Punctured convolutional codes for the 1-D partial-response channel
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.
Afilliation | , Communication Systems |
Project(s) | Simula UiB |
Publication Type | Journal Article |
Year of Publication | 1991 |
Journal | IEEE Transactions on Information Theory |
Volume | 37 |
Issue | 3 |
Pagination | 808-817 |
Publisher | IEEE |
Keywords | Convolutional codes, Decoding, Euclidean distance, Hamming distance |
DOI | 10.1109/18.79950 |