“…O VER the last two decades there has been a growing interest in methods for anonymous communication and in developing techniques for reasoning about information hiding properties in security protocols [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26]. This is mainly due to the applications of the anonymous communication to various fields such as e-voting, e-commerce, e-mail, e-cash and so on.…”