Think about this scenario with iMessage.

[qbiq]

Let's say that i live in Sweden but i work in Norway.

When i am in Sweden i allow all data traffic and sends iMessage from #1 to #2 in sweden. When travel to Norway i turn on data roaming so i can't use the data in Norway.

If #2 from Sweden send me a iMessage that will be sent as a iMessage "data" sms from Sweden to #1 wich is in Norway and got data roaming on and is not connected to any wifi.

In my world i will not receive the iMessage until i turn on data in someway, either by wifi or turn on the data in Norway. What i have understod is that iMessage is encrypted so if Apple should convert that iMessage to a regular SMS that wouldn't be encrypted without a notice?

Does anyone know how this works?

 

[Puonti]

If #2 from Sweden send me a iMessage that will be sent as a iMessage "data" sms from Sweden to #1 wich is in Norway and got data roaming on and is not connected to any wifi.

In my world i will not receive the iMessage until i turn on data in someway, either by wifi or turn on the data in Norway. What i have understod is that iMessage is encrypted so if Apple should convert that iMessage to a regular SMS that wouldn't be encrypted without a notice?

Does anyone know how this works?

I don't know about encryption, but my understanding is that iMessages will try to send the message as "data" first (if the selected contact can receive iMessages recipient), but if that fails the message is sent as SMS a moment later. You wouldn't need to wait until you get internet access back, as long as you have regular cellular coverage.

 

[qbiq]

Can anyone confirm this?

 

[Puonti]

Though we weren't in different countries (same office, in fact), I did a test with a co-worker of mine. He sent me three messages in succession and I changed the settings on my iPhone as follows:

Message 1: cellular data on, wifi on - iMessage received
Message 2: cellular data off, wifi on - iMessage received
Message 3: cellular data off, wifi off - SMS received 5 minutes after it was sent

 

[qbiq]

Sounds great but still not that great. So iMessage is not that secure as Apple want it to be, if they "decrypt" an iMessage and delivery it as a regular SMS i don't understand why they wanna claim that the iMessages is encrypted.

 

[Puonti]

Sounds great but still not that great. So iMessage is not that secure as Apple want it to be, if they "decrypt" an iMessage and delivery it as a regular SMS i don't understand why they wanna claim that the iMessages is encrypted.

Keep in mind that Apple's not actually delivering your SMS - your carrier is. They don't need to decrypt anything. I'm not an Apple engineer so I can't say for a fact this is how it works, but I would imagine they do it like this:

iPhone to Apple: "Hey, here's an encrypted copy of message X I want you to send to recipient Y."

Apple to iPhone: "Thanks, but we can't seem to reach recipient Y. Send your local copy of message X as SMS instead. We'll delete the encrypted data you sent us."

iPhone to carrier: "Hey, can you deliver this message X to recipient Y?"