Abstract
The modification of the number field sieve which Joux and Lercier recently used to compute logarithms
in a prime field of a record 120 decimal digits makes use of the notion of a virtual logarithm
of a prime ideal in a number ring.We provide necessary and sufficient conditions for their method to
succeed and give an explicit formula for the virtual logarithm of an ideal.
2004 Elsevier Inc. All rights reserved.
Keywords: Finite field; Discrete logarithm; Number field sieve