Unresolved Issues

Secure Multicast Discovery

It would be desirable for someone with the appropriate credentials to be able to quickly discover devices that they can monitor/control. However, in order to avoid the case where the loss of a single device leads to the compromise of the entire network, monitoring/control credentials are typically asymmetric. While OSCORE does support secure multicast, it only works with a symmetric key.

Possible solutions:

• Have two keys: An asymmetric one for monitoring/control, and a symmetric one for multicast discovery.
  • Pros: Fast.
  • Cons: Difficult to manage or revoke discovery key.
• Use unsecured multicast to discover devices which support SOM+SSM and then follow up each one with a secure unicast discovery request.
  • Pros: Secure. Single certificate means easier key management.
  • Cons: Slow when there are lots of devices. Must negotiate a new security session with each device.

Either approach could be adopted without any changes to the underlying security model.

Certificate Format

The certificate format is currently undefined, but assumed to ultimately be based on X.509. However, there could be benefits to having a compressed certificate format that expands to X.509, similar to Nest Weave Digital Certificates.