  Secure digital wireless communication underwater has become a key issue as
maritime operations shift towards employing a heterogeneous mix of robotic
assets and as the security of digital systems becomes challenged across all
domains. At the same time, a proliferation of underwater signal coding and
physical layer options are delivering greater bandwidth and flexibility, but
mostly without the standards necessary for interoperability. We address here an
essential requirement for security, namely a confirmation of asset identities
also known as authentication. We propose, implement, verify and validate an
authentication protocol based on the first digital underwater communications
standard. Our scheme is applicable primarily to AUVs operating around offshore
oil and gas facilities, but also to other underwater devices that may in the
future have acoustic modems. It makes communication including command and
control significantly more secure and provides a foundation for the development
of more sophisticated security mechanisms.
