This might be being reconsidered; I don't have the full details but I've seen some talk about attestation being expanded to handle roaming keys as well. I thin

This might be being reconsidered; I don't have the full details but I've seen some talk about attestation being expanded to handle roaming keys as well. I think that's a mistake -- I think there are a lot of security and UX considerations around roaming keys that make attestation not suitable: For example, what happens when a user moves between ecosystems and finds out after the fact that their new ecosystem isn't supported? Also does attestation for an ecosystem and not just for a device actually offer any strong security or phishing guarantees? Apple supports sharing passkeys with contacts, so what phishing protection are you actually getting here? I'm a little bit skeptical of attestation in general, but there are scenarios where some regulatory bodies might really want it, and many of these specific concerns don't exist for device-bound keys, and you do actually get some strong security guarantees from them, so attestation at least makes a bit more sense there. I look at a company asking for attestation for device-bound keys and think, "yeah, that makes sense, you want a strong security boundary around the key." But my point isn't to argue one way or another, just to point out that, yes, keychain-synced passkeys on devices like iOS don't support attestation right now. But I don't know if that's going to be the case in the future or how that will change when certification starts ramping up. > but Apple frustratingly just removed the option rather than leaving the choice to relying parties (websites). This makes their passkeys unusable for some regulated/sensitive use cases that did depend on attestation. I'm too far out from the tech to speak confidently about it and I'm sure there are considerations I'm not aware of, but it really seems to me from the outside that a key being synced or device-bound should have been an attribute of the passkey and not like an entirely separate system. I know there are considerations with hardware tokens and resident key limits, but I also suspect part of this is that roaming keys were a later addition, my understanding is that they were relatively controversial when first proposed and so maybe that led to them kind of evolving separately? I'm just guessing though. It is very weird that iOS requires passkeys to be roaming keys.