Comment by xp84
15 hours ago
It seems like it would be easily resolvable with TXT records these days. Anyone could try, say, on www.google.com to set a cookie for all of google.com, and the browser can fetch TXT records on google.com to see what, if any subdomains, it wants to allow this privilege for. Google could return a list or a wildcard; co.uk wouldn't allow any.
In a world without advertising, there's no reason why google.com couldn't also allow *.youtube.com to set cookies for it, but of course that would cause a tremendous privacy freakout. Though in practice they can and do just send every login/logout through a 302 redirect roundtrip to take care of the cookies on youtube.com.
Totally agree that a DNS based replacement to the suffix list would make sense. Especially with more secure forms of DNS like DoH or Dnssec.
That said I don't know about making cookies shareable across TLDs. That seems like allowing more privacy nightmares; at least today if you want to share you need complicated redirect dances that make you question if the user perf hit is worth it. I think there was some proposal for a mechanism for allowing non partitioned 3rd party cookies which seemed more sane to me, forget what the details were and if it ever made it beyond just a proposal.
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