For most boundary conditions other than refraction, the Wall feature can be used. It includes a wide variety of boundary conditions including the following:

If you choose Mixed diffuse and specular reflection you can assign some probability that the ray is reflected specularly; otherwise it is reflected diffusely.

The Diffuse scattering and Mixed diffuse and specular reflection rely on pseudorandom number generation, so they are not guaranteed to give exactly the same numeric results in different software versions or on different architectures.