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A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

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Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#41

Post by fmajid »

modeless wrote: post #15
snowwrestler wrote: post #14

Earlier quoted context omitted.

Only if you have “Messages in iCloud” turned on, which is optional.

This is false. If you turn off the "Messages in iCloud" feature then your messages are included in your regular iCloud backup which Apple has the keys to decrypt, as disclosed. Of course iCloud backup is itself optional. But Apple gives you and the people you're messaging no other option for cloud backups. ADP actually encrypts your backups, but since it defaults to off your messages are almost certainly still readab…

And of course ADP is off in the U.K., where I live. And iMessage sometimes randomly falls back to unencrypted SMS/MMS even when you ticked the checkbox disallowing this in System Settings.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#42

Post by isodev »

modeless wrote: post #2

All that security, and then by default Apple literally just sends themselves a copy of your encryption keys to store in iCloud backup, the only cloud backup solution Apple allows you to use. "to help you recover your data" [1] (oh and also to send law enforcement your message history in plaintext on request, but we don't talk about that). [1] https://support.apple.com/en-us/102651#:~:text=in%20iCloud%2...

I think the story around privacy and security in general has become diluted in marketing talk. Every single default on both iOS and macOS effectively makes one’s data, well, accessible and not private.

The gap between perception and reality when it comes to Apple as a “privacy champion” has never been so big as it is today.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#43

Post by snowwrestler »

modeless wrote: post #15
snowwrestler wrote: post #14

Earlier quoted context omitted.

Only if you have “Messages in iCloud” turned on, which is optional.

This is false. If you turn off the "Messages in iCloud" feature then your messages are included in your regular iCloud backup which Apple has the keys to decrypt, as disclosed. Of course iCloud backup is itself optional. But Apple gives you and the people you're messaging no other option for cloud backups. ADP actually encrypts your backups, but since it defaults to off your messages are almost certainly still readab…

> If you turn off the "Messages in iCloud" feature then your messages are included in your regular iCloud backup which Apple has the keys to decrypt, as disclosed.

No, if you do not use “Messages in iCloud” then your iMessage private key does not leave your device.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#44

Post by fmajid »

Jtsummers wrote: post #24
modeless wrote: post #13

Earlier quoted context omitted.

There's no guarantee, but some apps intended for security actually make at least a minimal effort to be excluded from plaintext backups, rather than intentionally sending their encryption keys to the backup service that just happens to be run by the same company...

Ok. So you concede that there is no way for you to ensure that messages you send me, that I can decrypt, are left unreadable by anyone but me. So what secure communication system should we be using given that none of them can guarantee that the recipient doesn't leak information to another country by choosing to use a compromised version of the client?

You are attacking a straw man. The risk is the your correspondent does not have ADP enabled, as it is not on by default, and not even offered in some authoritarian countries like the U.K., so even without their cooperation they can still get their key. I don’t know if iMessage implements Perfect Forward Secrecy, but at the very least they will be able to read all your messages moving forward.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#45

Post by snowwrestler »

tgma wrote: post #16
snowwrestler wrote: post #14

Earlier quoted context omitted.

Only if you have “Messages in iCloud” turned on, which is optional.

Actually it is the opposite. If you have Messages in iCloud, they do not store messages in "iCloud Backup" but keep it separate with some client-side device-to-device encryption key (UPDATE: which they also store a copy of inside iCloud backup unless ADP is on; thanks to 'modeless). If you enable iCloud Backup and Messages in iCloud is turned off, it will backup all your messages in a way visible to Apple servers. Of…

It is extremely simple, actually. Don’t use “Messages in iCloud” and don’t backup your Messages app to iCloud, and Apple cannot see your message content at all. Luckily these are the defaults.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#46

Post by modeless »

snowwrestler wrote: post #45
tgma wrote: post #16

Earlier quoted context omitted.

Actually it is the opposite. If you have Messages in iCloud, they do not store messages in "iCloud Backup" but keep it separate with some client-side device-to-device encryption key (UPDATE: which they also store a copy of inside iCloud backup unless ADP is on; thanks to 'modeless). If you enable iCloud Backup and Messages in iCloud is turned off, it will backup all your messages in a way visible to Apple servers. Of…

It is extremely simple, actually. Don’t use “Messages in iCloud” and don’t backup your Messages app to iCloud, and Apple cannot see your message content at all. Luckily these are the defaults.

It is definitely not the default to exclude iMessage from iCloud backups.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#47

Post by ronnieboy493 »

tgma wrote: post #38
gU9x3u8XmQNG wrote: post #36

Earlier quoted context omitted.

How are you achieving this? I’d like to know more. Thanks in advance.

Perhaps I should document it and link to it in detail but basically you use Apple Configurator to create a profile and set its restriction flags accordingly and keep it somewhere you can redeploy with ease and simply DFU restore the iOS device so that it gets the latest clean iOS image. After that you don’t activate it by going through the setup screen. Instead you use the connected Mac with Apple Configurator to “Pr…

> Perhaps I should document it and link to it in detail

Would be very interested in this.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#48

Post by __turbobrew__ »

londons_explore wrote: post #32
jjcob wrote: post #31

Earlier quoted context omitted.

The waiting time increases after failed attempts.

In general that isn't secure unless the security chip has access to a secure time server to know that the required amount of time has passed. Otherwise you can simply say "yeah, we power cycled you and now the year is 100,000, can I have another guess?" I don't see any mention of that functionality in any public documentation.

You can spoof GPS with a hackrf so this is not actually that crazy, I wouldn’t be surprised if certain 3 letter agencies have tried this already.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#49

Post by modeless »

snowwrestler wrote: post #43
modeless wrote: post #15

Earlier quoted context omitted.

This is false. If you turn off the "Messages in iCloud" feature then your messages are included in your regular iCloud backup which Apple has the keys to decrypt, as disclosed. Of course iCloud backup is itself optional. But Apple gives you and the people you're messaging no other option for cloud backups. ADP actually encrypts your backups, but since it defaults to off your messages are almost certainly still readab…

> If you turn off the "Messages in iCloud" feature then your messages are included in your regular iCloud backup which Apple has the keys to decrypt, as disclosed. No, if you do not use “Messages in iCloud” then your iMessage private key does not leave your device.

If you turn off Messages in iCloud then the messages are instead stored in your iCloud backup and encrypted "In transit & on server" with key storage by Apple, not just on your devices, as specified in the fourth row of the "Data categories and encryption" table in the Apple support article I linked. "In transit & on server" means not e2ee. That is, Apple can decrypt the messages at will without notice or consent.

If the messages were still protected by e2ee with key storage only on your devices then it would specify that in the table. Some other data types like keychain passwords and Memoji are in fact protected by e2ee even when ADP is not enabled, and the table reflects that. Messages do not fall in the category of e2ee without ADP.

Re: A Formal Analysis of Apple's iMessage PQ3 Protocol [pdf]

#50

Post by tgma »

ronnieboy493 wrote: post #47
tgma wrote: post #38

Earlier quoted context omitted.

Perhaps I should document it and link to it in detail but basically you use Apple Configurator to create a profile and set its restriction flags accordingly and keep it somewhere you can redeploy with ease and simply DFU restore the iOS device so that it gets the latest clean iOS image. After that you don’t activate it by going through the setup screen. Instead you use the connected Mac with Apple Configurator to “Pr…

> Perhaps I should document it and link to it in detail Would be very interested in this.

Feel free to send me a note to the email in the profile. I will make sure to link to you when I get to documenting this.
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