Apple could mitigate most of the security concerns listed in this thread by listing the trusted devices which you're encrypting against. This solves the "extra encryption key" angle. You'd still have to trust your recipient to be just as mindful of this as you to prevent the vulnerability in the other direction though.
Apple Explains How Secure iMessage Is
71–80 of 126 posts
Re: Apple Explains How Secure iMessage Is
#72Earlier quoted context omitted.
You're missing the part where "custom client" means you aren't using an Apple device at all, if you don't want to be. This is like sending a PGP message over gmail using mutt on linux via IMAP. Google owns gmail, but they can't backdoor you or read your message in this scenario. Any non-broken secure messaging protocol should have this property, regardless of if people use it that way. This is what end-to-end encrypt…
> Any non-broken secure messaging protocol should have this property Okay then, tell me how you could build a system that * Guarantees secure transmission of public keys * Can be installed safely on a closed-source operating system * Is impervious to the whims of the hardware vendor or the operating system vendor * Is sufficiently straightforward that mums everywhere will happily use it * Doesn't require users to bec…
No, Apple has definitely done worse than what we have expected. Worse, they haven't provided what they claimed. That being a secure end-to-end messaging protocol.
This discussion about backdooring applications isn't even interesting or relevant here. The protocol itself is not secure.
Re: Apple Explains How Secure iMessage Is
#73Earlier quoted context omitted.
If you see security as boolean, you're going to have a rough time...
Security is as strong as the weakest link. If there is a weak link there's no security. So, it is boolean.
Any more fuzzy platitudes for us, Geee?
The best encryption we have today is still bound to time and technology. Without a threat model, it's pointless to discuss security. To the NSA, not much of anything is secure on the Internet. There is a lot you can do when you have total visibility into all traffic. But your psychotic girl/boyfriend who barely understands what Wi-Fi is? They probably won't be eavesdropping on your iMessages.
Re: Apple Explains How Secure iMessage Is
#74It's worth re-reading this post by Matthew Green, "Can Apple read your iMessages?" [1] For one, if you back up your device with iCloud, then yes, Apple can read your iMessages. This has been verified by experiment. Second, Apple operates a central directory of iMessage public keys mapped to accounts, and this enables various kinds of MiTM attacks. Contrast this with the way TextSecure / RedPhone does contact discover…
It's still way better than SMS, and Facebook loves to use that kind of information to sell ads. This is actually more secure than I expected.
And it's far better than other messaging services where messages can be read by the server (e.g. Google talk). If they/the government wanted to read your messages, at last they'd have to jump through some hoops.
Re: Apple Explains How Secure iMessage Is
#75Obviously this system has limitations and entirely relies on your ability to trust Apple. But there's quite a few things to consider here: * Text messages and most other chat protocols require that you trust multiple hardware vendors, multiple software vendors, and multiple telcos. By comparison, iMessage only requires that you trust a single company, Apple. * As long as the operating system and messaging software is…
Most of these points are completely wrong.
> * Text messages and most other chat protocols require that you trust multiple hardware vendors, multiple software vendors, and multiple telcos. By comparison, iMessage only requires that you trust a single company, Apple.
This is incorrect. It requires you to trust Apple, every company who operates a CA, every government who can compel any CA to mint a certificate (read: you trust the Turkish and Chinese governments), your IT department, and any hacker who has access to any of those. If you didn't install the patch this week, and for the last year and a half, it required you to trust everyone on every network segment you have ever connected to from any Apple device.
> * This is about as secure as it could ever get without requiring users to be educated about security principles. Given that iMessage is foremost a seamless alternative to text messages, it's difficult to imagine how they could make it more secure without compromising utility.
It could very easily be more secure. For example, certificate pinning would be a decent start. It could also allow users to view key fingerprints if they choose to. Many users wouldn't understand the purpose of that exercise, but at least the option exists. More paranoid users could enable warnings if a user's key changes. See also: Whisper Systems
> * The implementation details mean that any Government snooping must be done with Apple's knowledge, and will require the blessing of Apple's legal department. This might not be a particularly high bar to cross, but it does mean that Governments aren't running rampant, analyzing every message sent.
Incorrect, as explained above. There are attacks that do not require governments nor do they require any assistance or blessing from Apple.
> * The United States government isn't the only bad actor out there. The level of security appears to be extremely good against entities that hold no sway with Apple's legal team. It's also presumably impervious to a hostile network, or hostile foreign governments.
It's not impervious to hostile networks if those networks include your corporate IT network or if you have used it in the past year and a half on any network. Even with the latest patches, it is not impervious to hostile foreign governments. Check your browser's CA list and take a look at how many different countries are in there. For a more complete list, take a look at this: https://www.eff.org/files/colour_map_of_CAs.pdf
Re: Apple Explains How Secure iMessage Is
#76Author isn't very clever about crypto attacks. Sending device grabs all of the recipients public keys (as well as all of their own keys for other devices, which allows the conversation to be replicated on all of their own devices as well) hosted by Apple. Sending device has no way to verify those keys belong to the intended recipient . User has no way to verify which, or how many devices they are sending to. User doe…
>Apple wants to read your messages? They drop one of their public keys in the list. Apple gets a warrant? They drop the FBI's key in the list. If they were doing this, it would come out real quick. You'd just send a message to a different account you control then see how many keys you're getting/encrypted messages you're sending. Someone like Applebaum, who knows he's under surveillance and has the crypto/networking…
Right, but isn't the point that they could do it in a targeted fashion? Granted, it beats the dragnet situation we have now, but it's not quite at the point of "Apple couldn't intercept your messages even if they wanted to".
Re: Apple Explains How Secure iMessage Is
#77Earlier quoted context omitted.
>Apple wants to read your messages? They drop one of their public keys in the list. Apple gets a warrant? They drop the FBI's key in the list. If they were doing this, it would come out real quick. You'd just send a message to a different account you control then see how many keys you're getting/encrypted messages you're sending. Someone like Applebaum, who knows he's under surveillance and has the crypto/networking…
Right, but isn't the point that they could do it in a targeted fashion? Granted, it beats the dragnet situation we have now, but it's not quite at the point of "Apple couldn't intercept your messages even if they wanted to".
Granted. That said, "Apple couldn't undetectably intercept your messages even if they wanted to" is surprisingly close.
Re: Apple Explains How Secure iMessage Is
#78Re: Apple Explains How Secure iMessage Is
#79Earlier quoted context omitted.
> iMessages you send are signed by your private key, which is probably not something you want. Why not?
Because they can be used against you and you won't be able to deny the message has originated from you, which is a desirable security/privacy property in a messaging app setting. OTR, and mpOTR[1] in particular, try hard to remove non-repudiability from messages. [1]: http://www.cypherpunks.ca/~iang/pubs/mpotr.pdf
I always thought non-repudiability was desirable and what whistleblowers need is anonymity. Thanks for that link.
Re: Apple Explains How Secure iMessage Is
#80Obviously this system has limitations and entirely relies on your ability to trust Apple. But there's quite a few things to consider here: * Text messages and most other chat protocols require that you trust multiple hardware vendors, multiple software vendors, and multiple telcos. By comparison, iMessage only requires that you trust a single company, Apple. * As long as the operating system and messaging software is…
Most of these points are completely wrong. > * Text messages and most other chat protocols require that you trust multiple hardware vendors, multiple software vendors, and multiple telcos. By comparison, iMessage only requires that you trust a single company, Apple. This is incorrect. It requires you to trust Apple, every company who operates a CA, every government who can compel any CA to mint a certificate (read: y…
Every one of your objections relies upon the assertion that iMessage is vulnerable to certificate forging attacks. Do you have a citation? Has this been demonstrated, or is it theoretical?