Bruce Dodson

Factorization of RSA-140 Using the Number Field Sieve

We propose a mathematical problem, and show how to solve it elegantly. This problem is related with elliptic curve cryptosystems (ECC). The solving methods can be applied to a new paradigm of key generations of the ECC.

A World Wide Number Field Sieve Factoring Record: On to 512 Bits

We present data concerning the factorization of the 130-digit number RSA130 which we factored on April 10, 1996, using the Number Field Sieve factoring method. This factorization beats the 129-digit record that was set on April 2, 1994, by the Quadratic Sieve method. The amount of computer time spent on our new record factorization is only a fraction of what was spent on the previous record. We also discuss a World Wide Web interface to our sieving program that we have developed to facilitate contributing to the sieving stage of future large scale factoring efforts. These developments have a serious impact on the security of RSA public key cryptosystems with small moduli. We present a conservative extrapolation to estimate the difficulty of factoring 512-bit numbers.

20 years of ECM

The Elliptic Curve Method for integer factorization (ECM) was invented by H. W. Lenstra, Jr., in 1985 [14]. In the past 20 years, many improvements of ECM were proposed on the mathematical, algorithmic, and implementation sides. This paper summarizes the current state-of-the-art, as implemented in the GMP-ECM software.

On the Factorization of RSA-120

We present data concerning the factorization of the 120-digit number RSA-120, which we factored on July 9, 1993, using the quadratic sieve method. The factorization took approximately 825 MIPS years and was completed within three months real time. At the time of writing RSA-120 is the largest integer ever factored by a general purpose factoring algorithm. We also present some conservative extrapolations to estimate the difficulty of factoring even larger numbers, using either the quadratic sieve method or the number field sieve, and discuss the issue of the crossover point between these two methods.

MPQS with Three Large Primes

We report the factorization of a 135-digit integer by the triple-large-prime variation of the multiple polynomial quadratic sieve. Previous workers [6][10] had suggested that using more than two large primes would be counterproductive, because of the greatly increased number of false reports from the sievers. We provide evidence that, for this number and our implementation, using three large primes is approximately 1.7 times as fast as using only two. The gain in efficiency comes from a sudden growth in the number of cycles arising from relations which contain three large primes. This effect, which more than compensates for the false reports, was not anticipated by the authors of [6][10] but has become quite familiar from factorizations obtained using the number field sieve. We characterize the various types of cycles present, and give a semi-quantitative description of their rather mysterious behaviour.

Computing rates of growth of division fields on CM abelian varieties

We report on algorithmic aspects of the problem of explicitly computing the rate of growth of the field of N k -th division points on an n-dimensional simple Abelian variety with Complex Multiplication. Two new examples are discussed.