The Internet of Things will scale to billions of devices in the next coming years. A secure communication framework is needed to interconnect all these objects, by taking into account their intrinsic constrained in terms of energy, cpu and memory; Several proposals relying on adapting existing well-known and standardized security solutions exist, but we believe there is still a gap for most-constrained nodes to provide fine-grained authorization and secure establishment of fresh cryptographic keys. We propose a mechanism that runs on top of the OAuth Authorization architecture and provides the bootstrapping of fresh authenticated symmetric cryptographic material between previously unknown parties using a nonce-based protocol. We set up an energy measurement platform to evaluate our proposal and compare it with existing work.