An Authenticated Received Chain (ARC) table was organized at the weekend hackathon held before the IETF 99 meeting in Prague this week. ARC is an official work item of the IETF DMARC Working Group, and will be discussed during the working group meeting Thursday morning.
Participants from two different vendors worked on new implementations of ARC, compatible with their software stacks. By the end of the weekend, one of these implementations was able to validated multiple-hop ARC chains, which is perhaps the hardest part of any implementation. And a participant from a third vendor indicated they have made significant progress in developing their own ARC implementation prior to the weekend.
If you compare this to all proprietary and open source implementations known before the hackathon, it will represent a 60% increase in the number of ARC implementations when they are completed. In addition to the implementation work mentioned, the weekend included a great deal of interoperability testing, bug hunting, patch generation, release building, and pull requests.
Many thanks to all the participants at the hackathon, whether they were in the room or working remotely!