I would assume one downside is a higher amount of spam. Currently you need to have an Apple device to send an iMessage. So sending spam is an expensive proposition.
If I want to spam you I buy a bunch of numbers on Plivo and start sending your number messages with SMS, the existing standard. They show up in iMessage on your phone. The only difference is they're green instead of blue.
So, how do I need an iPhone to send you spam? iMessage doesn't do anything related to spam other than let you delete and report it.
But if it did work that way, then the standard could include that messages need to be signed with a device attestation key from an approved vendor or something like that. There could be a way to have your attestation keys registered like we do for CAs today so that your attestation hardware could be used. Phone manufacturers would all implement device attestation, like Apple and Google do.
I know the difference between SMS and iMessage. Currently I get plenty of SMS spam. I get pretty much zero iMessage spam. I’m pretty sure that I would get more spam if iMessage was made interoperable, even if device attestation was implemented as you described. Some Googling suggests that RCS, the competing standard for messaging, does not implement device attestation.
Right, I'm just genuinely confused. How would you meaningfully distinguish between the spam? Why would there be more of it? Wouldn't it just come in blue instead of green? I'm not sure I understand how adding a 2nd avenue for spammers opens new doors when the existing avenue is totally sufficient. Perhaps if you could send messages from an email only account is what you're saying? Personally I would hope there'd be ways to control unsolicited messages in the messaging apps and report spam to the carriers. And honestly I was thinking that as an sms replacement, messages from email-only accounts would be something different carriers would want to gate/control onto the network as they see fit. Or more ideally the protocol itself could require messages to be signed with device attestation keys. Why iMessage doesn't give me better spam management options for existing SMS is the real question.
