For the past year Dstl have been developing a new class of JANUS for the transmission of ultra-compact, cryptographically secure messages. There is a growing need in the international community for sending encrypted C2 messaging in large but simple network topologies. To this end, we propose a new JANUS Class "Venilia".
This JANUS Class allows for the sending of short form factor (codebook) messages. We use codebook messaging as a method of requiring only the JANUS 64-bit baseline packet, reducing the chance of message collisions in congested environments and relieving some of the power strain on small deployed devices. The baseline 34-bit Application Data Block includes an 8-bit message ID, two 7-bit addresses, a 5-bit integrity-check CRC, a 5-bit Initialisation Vector for messaging uniqueness, and a 2-bit ambiguity resolution field. This last field is because Venilia resets its encryption outputs over time using adaptable-length epochs, providing long term sustainability of cryptographic security which is vital in such minimal message sizes. More information can be found here.
To meet the security needs of Venilia, Dstl and the National Cyber Security Centre (NCSC) have jointly developed the Tiny Underwater Blockcipher (TUBcipher) to encrypt 27 of the 34 bits of the Application Data Block. Despite the compact block sizes, TUBcipher utilises all of the components of larger ciphers, being underpinned by a cryptographic hash for key extension, and including the optimal permutation-substitution network for 3-bit words, among other stages. More information can be found here.
We hope the wider JANUS community find these useful, and that our proposal to adopt this as a new JANUS class is accepted. The specifications list a working title of JANUS Class 17, but obviously this is pending a review from this community. We have C and MATLAB code that can be implemented into the CMRE JANUS reference chain, and we are working to release this to the community.
We feel that this contribution towards JANUS helps further the goal of creating an interoperable ‘toolkit’ of applications to meet a variety of operational and scientific requirements. We look forward to joining the discussion of what a ‘secure’ class of JANUS looks like, our own proposition is just a stepping stone for a more flexible and adaptable approach to security of underwater messages.