Podcast
Root Causes 369: iMessage to Be PQC Enabled


Hosted by
Tim Callan
Chief Compliance Officer
Jason Soroko
Fellow
Original broadcast date
March 15, 2024
Apple has announced that iMessage will employ post-quantum cryptography (PQC). We explain the implications of this announcement.
Podcast Transcript
Lightly edited for flow and brevity.
iMessage was launched in 2011. And it was the first - - Apple is claiming the first end to end encrypted by default messaging app. And they moved, you know, this is perfect for this podcast because they talk about it in this - - paragraph one, they talk about being very proud of switching from the RSA algorithm to ECC, elliptic curve cryptography, in 2019. And now, what they're announcing is that they are actually going to be the very first wide scale messaging platform to actually use post-quantum. Now Signal has the PQXDH protocol but let's talk about PQ3 protocol, which is there's going to be a key establishment with PQ3, and also an ongoing rekeying.
And so getting - - this the reason to move to PQC as fast as you possibly can, not just to get comfortable with it and shake out the bugs and make sure it works correctly and those are all great reasons too, but also because everything that is PQC encrypted, starting now or starting a year ago, is going to be immune to the harvest and decrypt scenario and the more of all of our conversations and data and information exchanges that we get into PQC, the more we reduce that risk service for the quantum computer harvest and decrypt scenario.
“With PQ3, iMessage continues to rely on classical cryptographic algorithms to authenticate the sender and verify the contact key verification account key because these mechanisms cannot be attacked retroactively with future quantum computer.”
So that isn't like - - basically - -
“To attempt to insert themselves into the middle of an iMessage conversation, an adversary would require a quantum computer capable of breaking one of the authentication keys before or at the time the communication takes place. In other words, these attacks cannot be performed in a harvest now decrypt later scenario. They require the existence of a quantum computer capable of performing the attacks contemporaneously with the communication being attacked. We believe any such capability is still many years away but as the threat of quantum computers evolve, we will continue to assess the need for post quantum authentication to thwart such attacks.”
So what Apple has done is it's focused its attention on the area where the risk actually exists. And you can imagine lots of reasons why they wouldn't do it all at once, like just reduce the scope of the engineering challenge. And therefore the scope of the, you know, of the risk for flaws and whatnot. There's a lot of probably great reasons to chunk this up and do the things you need to do now now, and then deal with the other things as separate projects and I fully expect they will and the language in that suggests that eventually they will, but they recognize that it's not an urgent priority right now.
“I confirmed the PQ3 protocol provides post-quantum confidentiality, which can give users confidence in the privacy of their communication, even in the face of potential improvements in quantum computing technology.” That's a heck of a statement, Tim, from a guy who is like - - this is like the most pedantic of pedantic and pedantic gentleman you'll ever meet. And that's a compliment because if look, if Doug says so, guess what? You can take that to the bank.
The last thing I'll say about this is you and I talked right at the end of 2023 when we're doing our predictions for 2024. One of the things we said was that 2023 was the year that industry finally woke up to PQC. And 2024 was going to be the year that the enterprises and you know, the broader public was going to wake up to PQC. And we're really seeing that play out. And this is a perfect example like that. A major announcement from a major technology stack that got picked up all over the place in the media just shows where the zeitgeist is on PQC. And I think this is great. I think not a moment too soon.

