A collusion problem and its solution

摘要: Consider a group of colluders, each with certain knowledge such as the identity some other cryptographic keys, and data, possibly multiply encrypted. Two colluders can combine their if current satisfies conditions. Their keys help decrypt other's encrypted expanding revealing more collusion opportunities, process continues. The question we address is whether it possible for to uncover target set unencrypted data. In this paper formulate problem provide an algorithm that determines has solution and, so, computes one. A specific way by which hidden information. generated our generally not one involves minimum number colluders. We show, however, find NP-complete. Complex communications protocols employing building blocks are being developed transfer information among users hide from others. presented here be applied determine how subset protocol discover during or after protocol's execution them.