Encryption and keyrndistribution are important primitives to build secure Wireless Sensor Networksrn(WSN). Different block ciphers were proposed in literature to providernencryption in resource constraint distributed networks. A large amount ofrndifferent key distribution schemes were implemented, targeting different typesrnof WSNs. These schemes face issues with respect to their requirements,rnimplementations, and theoretic foundations. In this paper we provide anrnoverview of selected encryption schemes and introduce so called fault attacksrntargeting hardware implementations of block ciphers.rnSelected key pre-distribution schemes, like random key pre-distributionrnand hierarchical key distribution, are presented and depicted. Memory efficientrnElliptic Curve Cryptography (ECC) introduces feasible public key cryptographyrnschemes for WSNs. A summary of selected ECC based schemes is given with a focusrnon Identity Based Encryption (IBE), which is especially useful in scenariosrnwith a trusted sink node.