%% You should probably cite draft-ietf-core-oscore-groupcomm instead of this I-D.
@techreport{tiloca-core-multicast-oscoap-02,
    number =    {draft-tiloca-core-multicast-oscoap-02},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-tiloca-core-multicast-oscoap/02/},
    author =    {Marco Tiloca and Göran Selander and Francesca Palombini},
    title =     {{Secure group communication for CoAP}},
    pagetotal = 25,
    year =      2017,
    month =     jul,
    day =       1,
    abstract =  {This document describes a method for protecting group communication over the Constrained Application Protocol (CoAP). The proposed approach relies on Object Security of CoAP (OSCOAP) and the CBOR Object Signing and Encryption (COSE) format. All security requirements fulfilled by OSCOAP are maintained for multicast OSCOAP request messages and related unicast OSCOAP response messages. Source authentication of all messages exchanged within the group is ensured, by means of digital signatures produced through private keys of sender devices and embedded in the protected CoAP messages.},
}