Preface to Special Issue on General Secure Multi-Party Computation

More than a decade has passed since general results concerning secure two-party and multi-party computations were rst announced in 15, 24, 16] (see details in 14]). In a nutshell, assuming the existence of trapdoor permutations, these results assert that one can construct protocols for securely computing any desirable multi-party functionality. These results either require a majority of honest players or allow dishonest players to suspend the execution (while being detected as bad). Subsequent \unconditional" results in the \private channel model" require a 2/3-majority of honest player (cf., 4, 7]). The abovementioned results were presented at a time in which intensive electronic multi-party interactions seemed a remote possibility. So it seems fair to say that, while generating considerable interest within the theory community, these results generated little interest in the applied cryptography community. But times have changed: Intensive electronic multi-party interactions seems almost a reality, and the entire cryptographic community seems very much interested in a variety of natural problems which arise from such a reality. This has triggered the idea of having a special issue on general secure multi-party computation. Most of the current application-oriented interest is focused on the design of eecient and secure schemes for speciic purposes { Threshold Cryptography (cf., 10, 12]) is indeed a good example. Nevertheless, we believe that the general study of secure multi-party computation is important to practice. Firstly, this study clariies fundamental issues regarding security in a multi-party environment. Secondly, it draws the lines between what is possible in principle and what is not. Thirdly, it develops general techniques for design of secure protocols. And last, sometimes, it may even yield schemes (or modules) which may be incorporated in practical systems. Thus, we believe that the current special issue may be both of theoretical and practical interest. In order to put the papers of this special issue in perspective, it seems good to start with a short overview of the area.