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Post-Quantum Encryption No Longer a Laughing Matter

10 points by bpolania 11y ago

ryan-c 11y ago
> Now we have three patented improvements on top to make it truly NP-hard. And… semantically secure This pretty much means it won't become common before the patents expire if ever.
geofft 11y ago
Post-quantum crypto has never been a laughing matter of academic cryptographic research. That said, PQ Solutions' software is. Their main site isn't quite clear, but their app home page at https://pq-chat.com/ https://pq-chat.com/ spells out the problems clearly (starting with being an app home page): 1. It's available on the App Store, for iOS devices, which is secured by classical crypto. Anyone in their threat model (i.e., any attacker that would only be defeated by post-quantum encryption) can just break the classical signatures on App Store updates or iOS system updates and push out a compromised version. 2. From the FAQ (https://pq-chat.com/faq https://pq-chat.com/faq): > Does it mean access security is reliant on only a 5-digit PIN? > > Yes. We do offer additional security of access by using QR code, NFC or voice authentication. However, our research and user feedback indicate most users may not want a complicated way to get into the app. A 5-digit PIN seems to be an acceptable compromise between security and convenience. You don't need a quantum computer to brute-force this. For the entire lifetime of this app, quantum computers will be slower at brute-forcing 100,000 PINs than classical ones. 3. From the FAQ: > How can we tell if your app is safe? > > We appreciate a user may not want to trust a third party app. We have therefore incorporated a feature that, by pressing and holding a buddy’s name, all the text in the chat screen will be shown in Never-The-Same ciphertext in order to show you the encryption is working. I hope it's obvious that this is both completely untrustworthy and cryptographically useless. I'd dismiss this at marketing copy, but it's clearly an implemented feature (hover over the "Never-The-Same" picture at https://post-quantum.com/pqchat https://post-quantum.com/pqchat), which makes me worry about the technical background of the team in this discipline. The TechCrunch article seems to be implying that PQ Solutions is going after the enterprise / government market, which is a good market to go after, but you don't need fancy crypto for that. You just need a solid app that works and uses the state of the art in public crypto, and also isn't a general-audience chat app like WhatsApp so that IT doesn't block it. Any effort spent on research for the long-term is effort not spent on making the company sustainable. Go fight the government procurement and FIPS fights, get rich on classical crypto, sell and quit, and spend your time working with the public crypto community on research and on software development. Then you'll be solving the hard problems of how to move the entire world, including the iOS and App Store stack, HTTPS, etc., over to post-quantum encryption. Only in that world will your app be able to defend against an actual threat. Until then, talking about quantum computers is FUD -- FUD that might get you money now, but constrain you to spending time on research that's going nowhere.

10 points by bpolania 11y ago

> Now we have three patented improvements on top to make it truly NP-hard. And… semantically secure This pretty much means it won't become common before the patents expire if ever.

geofft 11y ago

Post-quantum crypto has never been a laughing matter of academic cryptographic research. That said, PQ Solutions' software is. Their main site isn't quite clear, but their app home page at https://pq-chat.com/ https://pq-chat.com/ spells out the problems clearly (starting with being an app home page): 1. It's available on the App Store, for iOS devices, which is secured by classical crypto. Anyone in their threat model (i.e., any attacker that would only be defeated by post-quantum encryption) can just break the classical signatures on App Store updates or iOS system updates and push out a compromised version. 2. From the FAQ (https://pq-chat.com/faq https://pq-chat.com/faq): > Does it mean access security is reliant on only a 5-digit PIN? > > Yes. We do offer additional security of access by using QR code, NFC or voice authentication. However, our research and user feedback indicate most users may not want a complicated way to get into the app. A 5-digit PIN seems to be an acceptable compromise between security and convenience. You don't need a quantum computer to brute-force this. For the entire lifetime of this app, quantum computers will be slower at brute-forcing 100,000 PINs than classical ones. 3. From the FAQ: > How can we tell if your app is safe? > > We appreciate a user may not want to trust a third party app. We have therefore incorporated a feature that, by pressing and holding a buddy’s name, all the text in the chat screen will be shown in Never-The-Same ciphertext in order to show you the encryption is working. I hope it's obvious that this is both completely untrustworthy and cryptographically useless. I'd dismiss this at marketing copy, but it's clearly an implemented feature (hover over the "Never-The-Same" picture at https://post-quantum.com/pqchat https://post-quantum.com/pqchat), which makes me worry about the technical background of the team in this discipline. The TechCrunch article seems to be implying that PQ Solutions is going after the enterprise / government market, which is a good market to go after, but you don't need fancy crypto for that. You just need a solid app that works and uses the state of the art in public crypto, and also isn't a general-audience chat app like WhatsApp so that IT doesn't block it. Any effort spent on research for the long-term is effort not spent on making the company sustainable. Go fight the government procurement and FIPS fights, get rich on classical crypto, sell and quit, and spend your time working with the public crypto community on research and on software development. Then you'll be solving the hard problems of how to move the entire world, including the iOS and App Store stack, HTTPS, etc., over to post-quantum encryption. Only in that world will your app be able to defend against an actual threat. Until then, talking about quantum computers is FUD -- FUD that might get you money now, but constrain you to spending time on research that's going nowhere.