1. A method implemented by a processor, the processor being coupled to a memory, the memory having a designated amount of storage available for storing values of a one-way chain, the designated amount of available storage being less than that required to store simultaneously all of the values of the one-way chain, the method comprising the steps of: storing in the memory a subset of the values of the one-way chain as helper values for facilitating computation of other values of the one-way chain not in the subset; utilizing one of the values in the subset of values to compute one of the other values of the one-way chain not in the subset; generating a cryptographic output determined by the computed value not in the subset; and updating the stored subset of values of the one-way chain so as to replace at least one of the helper values with a new helper value not previously part of the subset.