Computing Logarithms in Finite Fields of Characteristic Two

A simple algorithm to find logarithms in a finite field of characteristic two is described. It uses the Euclidean algorithm for polynomials in attempting to reduce an element to a product of factors all of whose logarithms are stored in a database. The algorithm, which is similar to one of Adleman, has a random runtime and constant storage requirements. It is analyzed and problems associated with the construction of the database are considered. The aim of the work is to show that the algorithm is feasible for the field with $2^{127} $ elements on which several proposed public key distribution systems have been based. For such application it is felt that the discrete logarithm is still a viable technique for sufficiently large fields.