Selective forgery of RSA signatures with fixed-pattern padding

We present a practical selective forgery attack against RSA signatures with fixed-pattern padding shorter than two thirds of the modulus length. Our result extends the practical existential forgery of such RSA signatures (Brier et al., 2001). For an n-bit modulus the heuristic asymptotic runtime of our forgery is comparable to the time required to factor a modulus of only 9/64 n bits. Thus, the security provided by short fixed-pattern padding is negligible compared to the security it is supposed to provid

Divisibility, Smoothness and Cryptographic Applications

This paper deals with products of moderate-size primes, familiarly known as smooth numbers. Smooth numbers play a crucial role in information theory, signal processing and cryptography. We present various properties of smooth numbers relating to their enumeration, distribution and occurrence in various integer sequences. We then turn our attention to cryptographic applications in which smooth numbers play a pivotal role