International Association for Cryptologic Research (IACR)
Abstract
We introduce a new class of computational problems which we
call the ``one-more-RSA-inversion\u27\u27 problems. Our main result is that
two problems in this class, which we call the chosen-target and known-target
inversion problems respectively, have polynomially-equivalent computational
complexity. We show how this leads to a proof of security for Chaum\u27s RSA-based
blind signature scheme in the random oracle model based on the assumed hardness
of either of these problems. We define and prove analogous results for
``one-more-discrete-logarithm\u27\u27 problems. Since the appearence of the
preliminary version of this paper, the new problems we have introduced
have found other uses as well