Abstract: Generic bootstrapping architecture (GBA) based procedures over Constrained Application Protocol (CoAP) for use in authenticating and/or securing communications with Internet of Things (IoT) devices are provided. In one illustrative example, the device sends to a bootstrapping server function (BSF) a first CoAP request carried in a Confirmable (CON) message, where the first CoAP request indicates a request for initiating a bootstrapping procedure. In response, the device receives from the BSF a first CoAP response carried in an Acknowledgement (ACK) message, where the first CoAP response indicates an authentication challenge. The device sends to the BSF a second CoAP request carried in a CON message, where the second CoAP request includes a challenge response to the authentication challenge. The device receives from the BSF a second CoAP response carried in an ACK message, where the second CoAP response includes a bootstrapping transaction identifier (B-TID) which indicates a successful authentication.