This article gives an overview of state-of-the-art side channel attacks and corresponding countermeasures which are currently discussed in the scientific literature. We compare different attacks with respect to the algorithms attacked, measurement costs, efficiency and practicability. In particular, we examine simple power analysis (SPA), differential power analysis (DPA), internal collision attacks and template attacks. Moreover, we give a brief overview of various countermeasures based on hard- or software which should always be implemented in order to secure cryptographic algorithms against side channel attacks.