I don't buy it. These systems are always multiparty. In a single party cryptosystem we can have internal integrity. We know we're not the bad guys and we didn't share the private information with the bad guys, therefore the bad guys don't have the data.

Once you're multiparty that goes away, any other party can definitely betray you and then it's game over, your own integrity doesn't matter.

Historically NOBUS was about having a particular technological lead, that's very fragile and didn't work out long term. If anybody has that lead today it's the Chinese, but realistically nobody has such a lead.

The other party doesn't even need to betray you, just have their systems compromised. See also, eg. : Salt Typhoon.

* https://en.wikipedia.org/wiki/2024_global_telecommunications... "The hackers were also able to access wiretapping systems used to conduct court-authorized wiretapping."

The argument about who the trustworthy "us" is is deeply uninteresting to me. I just care that there's precedent that if you stipulate the existence of such an "us", computer science does allow for NOBUS-y access mechanisms.