Group Assertion

This chapter begins by distinguishing between two kinds of group assertion—coordinated and authority-based—and it is argued that authority-based group assertion is the core notion. It is then shown that a deflationary view of group assertion, according to which a group’s asserting is understood in terms of individual assertions, is misguided. This is the case because a group can clearly assert a proposition even when no individual does. A positive inflationary view of group assertion is then developed, according to which it is the group itself that is the asserter, even though this standardly occurs through a spokesperson(s) or other proxy agent(s) having the authority to speak on behalf of the group. A central virtue of my account is that it provides the framework for distinguishing when responsibility for an assertion lies at the collective level and when it should be shouldered by an individual simply speaking for herself.

The Division of Labor and Proxy Agency

Chapter 13 first lays out the problem of proxy agency. An example of a proxy agent is a spokesperson for an organization. When the spokesperson, appropriately authorized, in the right conditions, with the right intention and message, speaks, we count the group as announcing something. Thus, it appears that the group does something but only one of its members acts. Proxy agency appears then to be inconsistent with the multiple agents analysis of collective action. Chapter 13 provides an account of proxy agency, focusing on the case of a spokesperson, that draws on the notion of a status function and constitutive agency to show it can be compatible with the multiple agents account of institutional action. Then it clarifies and extends the account by defending it against objections. Finally, it discusses the systematic use of the same terms in different senses in relation to individual and institutional agency.

Experimenting with Proxy Agents in Online Combinatorial Auctions

To promote online eBay-like combinatorial auctions, the authors experiment with a distributive agent based mechanism PRACA which attempts to address two research issues. First, the scheme uses an algorithm CompDL to incrementally solve the Winner Determination Problem under limited memory for any package that the bidder may be interested to bid at any time. This helps the bidder to bid effectively knowing the current state of the auction. CompDL thereby allows a large number of items to be put on auction. Second, PRACA supplies an autonomous proxy agent to each bidder who logs in to an ongoing auction; this agent bids on the bidder's behalf and relays data on requested packages to the bidder. Therefore, PRACA helps in reducing operational overheads of seller and bidder in online combinatorial auctions. Both schemes have been implemented and the efficacy of the approach is demonstrated by experiments.

A Provably Secure Proxy Signcryption Scheme Using Bilinear Pairings

As people in modern societies are busier than any human era and computer network has profound impact on how people work and live through fast and convenient information exchange, people need more help from each other to accomplish more work via network connections in limited period of time. Therefore, privilege delegation mechanism has become a necessary service in modern enterprises and organizations. Proxy signcryption scheme provides a secure privilege delegation mechanism for a person to delegate his privilege to his proxy agent to accomplish things. In 2010, Lin et al. had proposed an efficient signcryption scheme using bilinear pairings. However, we found that the proxy signcryption scheme of Lin et al. is vulnerable to the chosen warrant attack. A provably secure proxy signcryption scheme using bilinear pairings is introduced accordingly. In terms of performance efficiency, the proposed scheme is superior to other existing schemes. In addition, a new security model is proposed to describe proxy signcryption scheme; based on the security model we show that the proposed scheme is provably secure in terms of indistinguishability under adaptive chosen ciphertext attack (IND-CCA2), unforgeability under adaptive chosen message attack (EF-CMA), and unforgeability under adaptive chosen warrant attack (EF-CWA).

Design and Implementation of a Distributed Firewall

This chapter presents the design and the implementation of a decentralized firewall. The latter uses autonomous agents to coordinately control the traffic on the network. The proposed framework includes a set of controllers’ agents that ensure the packets filtering services, a proxy agent that plays a role of a proxy server and an identifier agent which is responsible for user authentication. The decentralization of the different agents’ activities is managed by an administrator agent which is a core point for launching the most important operations of the access control. A prototype has been designed and implemented. Furthermore, the authors hope that the underlying framework will inform researchers of a possible way to implement a decentralized firewall to improve the current solution, and will help readers understand the need for techniques and tools such as firewalls that are useful to protect their network traffic.