International Journal of Advanced and Applied Sciences, 4(3) 2017, Pages: 31-40 Contents lists available at Science-Gate International Journal of Advanced and Applied Sciences Journal homepage: http://www.science-gate.com/IJAAS.html 31 A fully distributed reputation system for m-commerce via ad hoc wireless networking Husna Osman 1, *, Munaisyah Abdullah 2 , Nur Zaimah Ahamad 1 1 System and Networking Section, MIIT, University Kuala Lumpur, Kuala Lumpur, Malaysia 2 Software Engineering Section, MIIT, University Kuala Lumpur, Kuala Lumpur, Malaysia ARTICLE INFO ABSTRACT Article history: Received 3 November 2016 Received in revised form 9 January 2017 Accepted 11 January 2017 Trust development among traders in an ad hoc m-commerce trading system is vital to mitigate uncertainty and risks involved in transactions. It helps traders decide whether to trade with potential trading partners as well as to gauge the degree of confidence that they should give these parties. One way to facilitate such trust is through use of a reputation system. However, the potential for ill-intentioned traders to subvert the reputation system makes the task challenging. This paper discusses key issues in designing a reputation system that can effectively facilitate trust development in such a loose and dynamic trading community. It proposes a fully distributed approach that employs a sanction-backed mechanism to encourage traders to be truthful in providing reputation reports. It advocates letting traders maintain their own reputation information as well as share knowledge about other traders’ trading behavior in a peer-to-peer (P2P) manner without relying on network services that are always available. A security analysis on the proposed design shows that it can help traders detect or mitigate the identified misbehavior-related threats to a sufficient degree. Keywords: Casual local trading Ad hoc community Infrastructure-less service Peer-to-peer service © 2017 The Authors. Published by IASE. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). 1. Introduction *To be a viable means to conduct online trading, ad hoc m-commerce (Osman and Taylor, 2008) must mitigate uncertainty and risks in its transactions by providing a means to foster trust among traders. A reputation system can be an effective means to do this. It provides a collaborative method for traders to assess the trustworthiness as well as predict the future behavior of other traders based on sharing past trading history and testimonials of trade worthiness. It helps traders choose reputable parties to trade with and avoid dealing with dubious ones. However, designing a reliable reputation system for ad hoc m-commerce trading systems is challenging as traders cannot be expected to spend lengthy periods of time to obtain their potential trading counterparties' reputation reports. Casual online trading is likely to take place over fairly short periods and not on an extended basis due to unpredictable network connectivity and irregular participation by its members. Traders in this type of * Corresponding Author. Email Address: husna@unikl.edu.my (H. Osman) https://doi.org/10.21833/ijaas.2017.03.006 2313-626X/© 2017 The Authors. Published by IASE. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) online trading will sometimes have to make rapid decisions whether to trade or not with a potential trading counterparty. Delays in making such decisions due to having insufficient reputation information might cause a trader to lose a rare opportunity to trade for a valuable resource or item as he might not be offered the same chance again in the foreseeable future. Another important issue is that ill-intentioned traders might try to subvert the reputation system by compromising the reliability of its reputation reports. To be effective in assisting traders make fast and reasonably founded trust decisions, a reputation system for ad hoc m-commerce trading systems must provide high availability and efficient retrieval of relevant reputation information as well as be robust against the sort of attacks that could compromise the reliability of this information. This paper presents the design of a distributed reputation system that lets traders maintain their own reputation information locally and share their knowledge about other traders’ trading behavior in a totally P2P manner without having to rely on network services that are always available. It advocates reinforcing this with a sanction-backed mechanism that lets traders collaborate to exclude any member that has misbehaved or has a poor