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> iMessage has always been maximally private from day one. However a drawback to the current implementation is that new devices cannot sync message history. No

by dsacco 9y ago

> iMessage has always been maximally private from day one. However a drawback to the current implementation is that new devices cannot sync message history. No it hasn't and yes they can. I've done it several times. The ability to restore messages to a device is specifically what breaks the otherwise end-to-end encrypted iMessage architecture, which is why Federighi talking about the new iOS 11 capabilities is intriguing. To your last point, my personal hypothesis is that Apple has designed a cryptosystem that uses a PKI with redundant key pairs to extend the redundant encryption. That shifts the recovery usability solution from redundant trusted devices to redundant keys that are written down.

abalone 9y ago
> I've done it several times. The ability to restore messages to a device... Interesting. To be clear, you're not just talking about restoring messages to the same device, like after resetting it? Looking more closely at Apple's security whitepaper, perhaps restoring history on a new device is possible if you enable iCloud Keychain. Looks like that would in fact share the private decryption keys among devices.[1] Ah, and that more clearly points at what this iMessage change may be: Mandatory iCloud Keychain, at least as far as iMessage keys are concerned. Which would suggest another, hidden improvement: no more need to redundantly encrypt a copy of every message for every recipient device! I want to add however that this still does not suggest anything about changing the security of backups, which was the implication of the article. Nor would I necessarily characterize iCloud keychain as "breaking" encrypted architecture. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf
- dsacco 9y ago
  Yes, I mean restoring to a new device. See here: https://blog.cryptographyengineering.com/2013/06/26/can-apple-read-your-imessages/ https://blog.cryptographyengineering.com/2013/06/26/can-appl...
  - abalone 9y ago
    It sure sounds like you're talking about restoring from backups. There's nothing in that article that suggests you'd normally be able to sync iMessages to a new device apart from restoring from a backup. And that's expected behavior. I just noticed that you misquoted me.. I said iMessage syncing has always been maximally private, and drew a distinction between that and backups. The article you cite mentions the tradeoff between strong cryptography (maximal privacy) and user pain (losing your data forever). Apple has made the intentional design choice of enabling the former for syncing but allowing backups to survive an account password reset. I think it's pretty clear that's a good choice for a consumer device. You can always turn off iCloud backups and back up locally via iTunes if you want maximal backup privacy.

by dsacco 9y ago

abalone 9y ago

> I've done it several times. The ability to restore messages to a device... Interesting. To be clear, you're not just talking about restoring messages to the same device, like after resetting it? Looking more closely at Apple's security whitepaper, perhaps restoring history on a new device is possible if you enable iCloud Keychain. Looks like that would in fact share the private decryption keys among devices.[1] Ah, and that more clearly points at what this iMessage change may be: Mandatory iCloud Keychain, at least as far as iMessage keys are concerned. Which would suggest another, hidden improvement: no more need to redundantly encrypt a copy of every message for every recipient device! I want to add however that this still does not suggest anything about changing the security of backups, which was the implication of the article. Nor would I necessarily characterize iCloud keychain as "breaking" encrypted architecture. [1] https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf

dsacco 9y ago
Yes, I mean restoring to a new device. See here: https://blog.cryptographyengineering.com/2013/06/26/can-apple-read-your-imessages/ https://blog.cryptographyengineering.com/2013/06/26/can-appl...
- abalone 9y ago
  It sure sounds like you're talking about restoring from backups. There's nothing in that article that suggests you'd normally be able to sync iMessages to a new device apart from restoring from a backup. And that's expected behavior. I just noticed that you misquoted me.. I said iMessage syncing has always been maximally private, and drew a distinction between that and backups. The article you cite mentions the tradeoff between strong cryptography (maximal privacy) and user pain (losing your data forever). Apple has made the intentional design choice of enabling the former for syncing but allowing backups to survive an account password reset. I think it's pretty clear that's a good choice for a consumer device. You can always turn off iCloud backups and back up locally via iTunes if you want maximal backup privacy.