24,304 research outputs found
An optimistic fair e-commerce protocol for large e-goods
Suppose two entities that do not trust each other want to exchange some arbitrary data over a public channel. A fair exchange protocol ensures that both parties get what they want or neither gets anything. In this paper, a fair e-commerce protocol for large e-goods is proposed and implemented. The proposed protocol provides a method for the fair exchange of e-money for e-products, and a method for verifying the contents of the exchanged items. The protocol is optimistic and efficient such that when none of the parties tries to cheat, only three messages are sufficient. In case of disputes, three more messages are needed. Furthermore, the customer remains anonymous after the transaction; thus, no information about the customers' shopping habits can be gathered through the protocol. The implementation results show that the protocol is efficient and secure and that only a small number of cryptographic operations is sufficient
A Fair and Secure Cluster Formation Process for Ad Hoc Networks
An efficient approach for organizing large ad hoc networks is to divide the nodes
into multiple clusters and designate, for each cluster, a clusterhead which is responsible for
holding intercluster control information. The role of a clusterhead entails rights and duties.
On the one hand, it has a dominant position in front of the others because it manages the
connectivity and has access to other node¿s sensitive information. But on the other hand, the
clusterhead role also has some associated costs. Hence, in order to prevent malicious nodes
from taking control of the group in a fraudulent way and avoid selfish attacks from suitable
nodes, the clusterhead needs to be elected in a secure way. In this paper we present a novel
solution that guarantees the clusterhead is elected in a cheat-proof manner
PKI Scalability Issues
This report surveys different PKI technologies such as PKIX and SPKI and the
issues of PKI that affect scalability. Much focus is spent on certificate
revocation methodologies and status verification systems such as CRLs,
Delta-CRLs, CRS, Certificate Revocation Trees, Windowed Certificate Revocation,
OCSP, SCVP and DVCS.Comment: 23 pages, 2 figure
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