In this talk, I will present some results obtained during my Ph.D on integer factorization and discrete logarithm computation in finite fields. First, I will present the ECM algorithm for integer factorization and a new method to analyze the elliptic curves used in this algorithm by studying the Galois properties of division polynomials. Then, I will talk about the NFS algorithm for integer factorization and in particular the polynomial selection step for which I will propose improvements of existing algorithms. Finally, I will talk about a common step of the NFS algorithm for integer factorization and the NFS-DL and FFS algorithms for discrete logarithm computations: the filtering step. I will explain this step thoroughly and present an improvement for which I will study the impact using data from several computations of discrete logarithms and factorizations.