1. A system for exchanging a transformed message with enhanced privacy, comprising: a defined set of input messages; a defined set of output messages; a module to select a message from the input messages set, and to efficiently transform one or more words in the selected message directly into a transformed message different from the selected message, wherein the transformed message belongs to the set of output messages, at least one component of the selected message is recoverable from the transformed message, and the cost of determining whether the transformed message belongs to the input messages set or the output messages set exceeds a defined threshold.