Technical Report TR-98-8B, LCIS, Tamkang University, Taiwan, R.O.C., July 1998.

Abstract. In 1995, Shamir proposed a variant of the RSA cryptosystem in which one of the two secret primes is much larger than the other one. Some "attacks" were subsequently reported by Gilbert, Gupta, Odlyzko and Quisquater. In this report, we show that the cryptosystem recently proposed by Okamoto and Uchiyama (EUROCRYPT '98) is subject to similar attacks.