We present an efficient, scalable, and renewable hierarchical random key predistribution (KPD) scheme as an enabler for a low complexity security infrastructure. As the proposed KPD scheme employs only symmetric cryptographic primitives it permits resource constrained nodes to take part in the deployment. Further, two nodes need to exchange only their IDs before they can establish a shared secret. The proposed KPD scheme provides scalable security for different levels of the hierarchy depending on available resources. In addition higher levels of the hierarchy are protected from security breaches in lower levels.