I'd like to offer my opinion on this topic, everything that follows is IMHO:
First off.....should we start a separate thread for a conversation on digital signatures / identification in Amateur Radio? Hopefully this isn't distracting too much from the main point of the thread for helping to collect up secondary mission ideas for Drew and the potential new partners. I'm saying that, because I'm about to dilute the thread with my opinion on digital signatures (hi hi), and feel bad that I might be distracting from the main point (long emails......but this stuff is just too cool)......
I'd like to voice my support for the concept of digital signatures for this type of concept of operation (CONOP) for an Amateur Radio spacecraft (but not all satellite CONOPs).
This type of operation is probably coming one way or another as technology evolves with the introduction of more advanced payloads to the hobby, depending on mission needs......and the sooner we can start trying it out, and trying to make it easier for hams to use (for the implementers out there) I think is a good thing. I think I can see both sides of the coin here.....and I think the trick is the devil in the details and in the method of 'enforcement'. Amateur radio has prided itself on being a 'self-regulating' entity, and for Zach's example, I would argue that there are mechanisms in place such as the ARRL Monitors Program that work with the FCC to potentially self-correct misconduct within the service or escalate 'flagrant violations' to the FCC. For a satellite, that method of enforcement is much more difficult.....and the methods used to identify an illegal/inappropriate HF station simply wouldn't work for the image upload CONOP. Something like a digital signature mentioned by Cathyrn is one way to create that type of capability for a spacecraft. There is a delicate balance that needs to be struck between ease of use if you want folks to operate with something new, but control is also very important.
When we were working on the GEO (Phase4B) payload back when there was more momentum, this specific issue came up for controlling user access to the digital transponder. Remember that one of the main mission objectives was emergency communications. Authentication of a user was very important for this, especially for prioritization of satellite resources and availability. Some folks may remember talk about 'emcomm mode' vs. 'anyone can play mode.' One idea for what one of the differences between those two modes would be is whether or not users are being authenticated and allowed access to the bird. In one version of the idea, when in EMCOMM mode, a 'whitelist' of authorized users would be allowed to use transponder resources, those users specifically involved in the emcomm event that needed the transponder. There were even discussions about whether or not we should *always* authenticate users, because with a 24/7 GEO resource....well, put simply, satellite piracy is a real thing, and we need a mechanism to deal with it.
Without getting bogged down in the technical details of that particular GEO attempt, I just wanted to say we specifically considered Log of the World for the mechanism for generating the credentials to identify a user. Having a single certificate authority for all things 'Ham Radio' is a good idea so that users only have to create their identity 'once' and not have to keep doing it for each new mission....LoTW is something that many hams are 'used to' and is something maintained at a central place familiar to hams. Its seems like the 'easiest' way to get folks to 'register' for the ability to access the satellite. Yeah, its an additional step to get on the air...but hopefully one most have already taken, and one that's not hard to take for those who haven't, and the payoff for taking the step is access to a really cool new capability! In this way, we have the ability to lock out illegal operators (that may not even be licensed Hams) and/or inappropriate users, and a way for us to prioritize use for EMCOMM situations......very important if lives are at stake.
There's a lot more detail behind this for the ideas around how the authentication process would actually work that I won't get into.....no actual decisions were made, but a lot of really really good conversations about how to ensure we can control the resource and keep it open for use to as many hams as possible with the least amount of burden (for the user, not necessarily least amount of burden for the designers/control operators), maximize it's utility during EMCOMM events, and not run afoul of FCC either through illegal/inappropriate use of the resource that we are unable to 'self-regulate' against but also make sure we don't run afoul of them in the way we implement the solution (authentication conversations can sometimes turn into encryption conversations.....no go for Amateur Radio, but all ideas are good ideas when brainstorming a solution to a tough problem). Basically, we wanted a way to remove the bad apple from the bag, rather than spoil the bunch (i.e. turn off the whole system) because we didn't have a way to deal with the bad apple.
Summary: I think the digital signature idea is a good one, I think LoTW is a good candidate for the certificate authority, and I think considering this type of operation within the constraints of part 97 rules when implemented helps set us up to keep our spectrum and keep it 'self regulated' as technology evolves.......and the sooner we start testing/demonstrating these capabilities, the better off we are.
Again, all above is IMHO.
Sincerely, -The 'other' Zach, KJ4QLP (N0ZGO is the main 'Zach' because he's getting it done on Golf!)
P.S. To be clear, I do NOT think we need this type of thing for every type of Amateur Radio communication or even every future satellite.....for the image upload example, and the GEO example, I think it makes sense at least in terms of one option to consider for a solution......there could be other solutions to the issue.