Technical Report TR-98-6, LCIS, Tamkang University, Taiwan, R.O.C., May 1998.
To appear in Proc. of the 1998 International Computer Symposium, Tainan (Taiwan, R.O.C.), 17-19th Dec. 1998.

Abstract. This report considers the problem of efficiently generating a sequence of secrets with the special property that the knowledge of one or several secrets does not help an adversary to find the other ones. This is achieved through one-way cross-trees, which may be seen as a multidimensional extension of the so-called one-way chains. In a dual way, some applications require the release of one or several secrets; one-way cross-trees allow to minimize the amount of data necessary to recover those secrets and only those ones.