The financial markets have been started to get decentralized and even distributed. Consumers can now purchase stocks from their home computers without the use of a traditional broker. The dynamism and unpredictability of this domain which is continuously growing in complexity and also the giant volume of information which can affect this market, makes it one of the best potential domains to take advantage of agents. This thesis considers the main concerns of securities e-trading area in order to highlight advantages and disadvantages of multi-agent negotiating systems for online trading of securities comparing to single-agent systems. And then presents a multi-agent system design named MASTNA which considers both decision making and negotiating. The design seeks to improve the main concerns of securities e-trading such as speed, accuracy and handling complexities. MASTNA works over a distributed market and engages different types of agents in order to perform different tasks. For handling the negotiations MASTNA takes advantage of mobile negotiator agents with the purpose of handling parallel negotiations over an unreliable network (Internet).

The enormous growth of the Internet and the World Wide Web has provided the opportunity for an enterprise to extend its boundaries in the global business environment. While commercial functions can be shared among a variety of strategic allies - including business partners and customers, extranets appear to be the cost-effective solution to providing global connectivity for different user groups. Because extranets allow third-party users into corporate networks, they need to be extremely secure and external access needs to be highly controllable. Access control and authorisation mechanisms must be in place to regulate user access to information/resources in a manner that is consistent with the current set of policies and practices both at intra-organisational and cross-organisational levels. In the business-to-customer (B2C) e-commerce setting, a service provider faces a wide spectrum of new customers, who may not have pre-existing relationships established. Thus the authorisation problem is particularly complex. In this thesis, a new authorisation scheme is proposed to facilitate the service provider to establish trust with potential customers, grant access privileges to legitimate users and enforce access control in a diversified commercial environment. Four modules with a number of innovative components and mechanisms suitable for distributed authorisation on extranets are developed: * One-shot Authorisation Module - One-shot authorisation token is designed as a flexible and secure credential for access control enforcement in client/server systems; * Token-Based Trust Establishment Module - Trust token is proposed for server-centric trust establishment in virtual enterprise environment. * User-Centric Anonymous Authorisation Module - One-task authorisation key and anonymous attribute certificate are developed for anonymous authorisation in a multi-organisational setting; * Agent-Based Privilege Negotiation Module - Privilege negotiation agents are proposed to provide dynamic authorisation services with secure client agent environment for hosting these agents on user's platform