Selective Receipt in Certified E-mail [chapter]

Steve Kremer, Olivier Markowitch
2001 Lecture Notes in Computer Science  
Traditional pen and paper transactions are becoming more and more replaced by equivalent electronic services. Therefore electronic e-mail should also provide enhanced services as those provided by traditional mail. In this paper we present new optimistic protocols for certified e-mail. The major contribution of our paper is the definition of a new property, specific to certified e-mail: no author-based selective receipt. This property requires that once the identity of the author of the mail is
more » ... known, the receipt can not be refused any more. We present two certified e-mail protocols respecting this property. First solutions to these exchange problem were based on gradual exchange protocols [13] . The disadvantages of this approach are the requirement of equivalent computational power and the network overhead. The second approach is a probabilistic one [4, 9] . Generally, the probability to cheat the other entity can be decreased by increasing the number of messages necessary in the protocol. To avoid the communication overhead, a different approach using a trusted third party (TTP) has been introduced. Both entities can send their items to the TTP that forwards them to the respective entities. However, this may create a communication and computation bottleneck at the TTP. To overcome this bottleneck, independently, Micali and Asokan et al. [1] introduced the optimistic approach in the context of fair exchange protocols. The rationale is that the TTP only intervenes in case of a problem, i.e. an entity is trying to cheat or a communication fails at a crucial moment. In an optimistic protocol, the TTP is said to be offline, while it is online in non-optimistic protocols. The optimistic approach has received most attention in recent literature.
doi:10.1007/3-540-45311-3_14 fatcat:ev3pe3nprnfkbkr65awv2uhq44