In the analysis of security protocols, methods and tools for reasoning about protocol
behaviors have been quite effective. We aim to expand the scope of those methods and …

Spam filters often use the reputation of an IP address (or IP address range) to classify email
senders. This approach worked well when most spam originated from senders with fixed IP …

A resource may be abused if its users incur little or no cost. For example, e-mail abuse is
rampant because sending an e-mail has negligible cost for the sender. It has been …

In recent years, email spam has become an increasingly important problem, with a big
economic impact in society. In this work, we present the problem of spam, how it affects us …

Recently, online social networking sites have exploded in popularity. Numerous sites are
dedicated to finding and maintaining contacts and to locating and sharing different types of …

A significant and growing class of location-based mobile applications aggregate position
data from individual devices at a server and compute aggregate statistics over these position …

Online communication media such as email, instant messaging, bulletin boards, voice-over-
IP, and social networking sites allow any sender to reach potentially millions of users at near …

As with any other emerging system, the analysis of the security of Peer-to-Peer Session
Initiation Protocol systems is of crucial importance for its secure development and future …

Abstract Voice-over-IP (VoIP) has become an attractive alternative to the plain old telephone
system, especially due to the much lower communication costs. However, there are several …

If communication involves some transactions cost to both sender and recipient, what policy
ensures that correct messages--those with positive social surplus-get sent? Filters block …