The morphology of fractured rock surfaces is studied in terms of their scaling invariance. Fresh brittle fractures of granite and gneiss were sampled with a mechanical laboratory profilometer, and (1+1)-dimensional parallel profiles were added to build actual maps of the surfaces. The systematic errors of the scaling analysis are estimated for the different methods. Isotropy of the scaling invariance within the mean fracture plane is shown either with the result obtained from different fracture orientations or with the two-dimensional Fourier spectrum of the surface topography itself. The analysis is brought further into the multifractal framework. The multifractal behavior is significant for physical properties which depend on high-order moments like contact. According to this study, the self-affine exponent is constant over a large range of scales and for different fracture modes and various materials. This opens the possibility that there exists a form of universality in the cracking process. -from Authors