Secure bootstrapping is the process by which a device gets the necessary configuration information and security credentials to become operational. In many pervasive computing and Internet-of-Things scenarios, it is often not possible to rely on the existence of a trusted third party or other network infrastructure for bootstrapping. Therefore, several device bootstrapping protocols rely on an out-of-band (OOB) channel for initial device authentication and configuration. We begin this paper by understanding the need for OOB channels and performing a literature survey of existing standards and devices that rely on OOB channels. We then look at one candidate bootstrapping protocol: Nimble out-of-band authentication for EAP (EAP-NOOB). We provide a brief overview of the EAP-NOOB protocol and describe its unique OOB channel requirements. Thereafter, we implement three OOB channels for EAP-NOOB using near-field communication, quick response codes, and sound. Using our implementation, we evaluate the usability, security, benefits, and limitations of each of the OOB channels.

The emergence of radio technologies, such as Zigbee, Z-Wave, and Bluetooth Mesh, has transformed simple physical devices into smart objects that can understand and react to their environment. Devices, such as light bulbs, door locks, and window blinds, can now be connected to, and remotely controlled from, the Internet. Given the resource-constrained nature of many of these devices, they have typically relied on the use of universal global shared secrets for the initial bootstrapping and commissioning phase. Such a scheme has obvious security weaknesses and it also creates undesirable walled-gardens where devices of one ecosystem do not inter-operate with the other. In this paper, we investigate whether the standard Extensible Authentication Protocol (EAP) framework can be used for secure bootstrapping of resource-constrained devices. EAP naturally provides the benefits of per-device individual credentials, straightforward revocation, and isolation of devices. In particular, we look at the Nimble out-of-band authentication for EAP (EAP-NOOB) as a candidate EAP authentication method. EAP-NOOB greatly simplifies deployment of such devices as it does not require them to be pre-provisioned with credentials of any sort. Based on our implementation experience on off-the-shelf hardware, we demonstrate that lightweight EAP-NOOB is indeed a way forward to securely bootstrap such devices.