Thanks for the reply. So am I misunderstanding their data security overview page?[0]
>For additional privacy and security, 14 data categories — including Health and passwords in iCloud Keychain — are end-to-end encrypted. Apple doesn't have the encryption keys for these categories, and we can't help you recover this data if you lose access to your account. The table below includes a list of data categories that are always protected by end-to-end encryption.
The table includes Messages in iCloud with the caveat that the key is stored in iCloud backups if enabled, but the e2e key is still private, no?
iCloud Backups are enabled by default, and the Messages in iCloud key is in the non-e2ee iCloud Backup.
That means the iMessages being synced are encrypted to an endpoint key which is held by both the endpoint and the middle transit service (iCloud/iCloud Backup). That's end-to-middle-and-end encrypted, i.e. not end to end encrypted.
Even if you turn on iCloud Backup e2ee (it's an option now) then your iMessages to everyone who hasn't (99.9%+ of people) aren't e2ee because the other end of the conversation is backing up their endpoint sync key.
>For additional privacy and security, 14 data categories — including Health and passwords in iCloud Keychain — are end-to-end encrypted. Apple doesn't have the encryption keys for these categories, and we can't help you recover this data if you lose access to your account. The table below includes a list of data categories that are always protected by end-to-end encryption.
The table includes Messages in iCloud with the caveat that the key is stored in iCloud backups if enabled, but the e2e key is still private, no?
[0]https://support.apple.com/en-us/HT202303