In recent years, the number of Internet users has increased very significantly. The utilization of the Internet for business purposes is everyday more factual. However this exponential growth of Internet users and networks has provoked an equivalent augment of malicious users. Hackers can take advantage of the low security level of the network, and hence, access to the valuable information exchanged through it. As a huge amount of electronic shopping choices become available, the reputation and interest of merchants and users have an economic value and probable costly consequences. Therefore, security mechanisms are needed for protecting the exchange of this type of information. When agents are representing users in Electronic Commerce scenarios, they are intended to cooperate with their trusted agents sharing recommendations about third parties, which represents the implementation of an electronic ‘word of mouth’. In this way, only the members of the group of agents should be authorized to access to its recommendations. This particular problem requires sharp responses according to computer performance, since it is supposed to be executed in real time. So typical approach –communications protection based on public key encryption- will be avoided in order to improve the efficiency.
In this paper, we propose some security mechanisms to be applied in such specific domain: electronic communities of agents sharing recommendations about merchants. As each agent establishes its electronic community and this group of agents is short-lived and all of them will receive exactly the same messages, then we propose a protection based on the combination of hash chains and symmetric encryption.
