Proton Mail, the leading privacy-focused email service, is making its first foray into blockchain technology with Key Transparency, which will allow users to verify email addresses. From a report: In an interview with Fortune, CEO and founder Andy Yen made clear that although the new feature uses blockchain, the key technology behind crypto, Key Transparency isn’t “some sketchy cryptocurrency” linked to an “exit scam.” A student of cryptography, Yen added that the new feature is “blockchain in a very pure form,” and it allows the platform to solve the thorny issue of ensuring that every email address actually belongs to the person who’s claiming it.
Proton Mail uses end-to-end encryption, a secure form of communication that ensures only the intended recipient can read the information. Senders encrypt an email using their intended recipient’s public key – a long string of letters and numbers – which the recipient can then decrypt with their own private key. The issue, Yen said, is ensuring that the public key actually belongs to the intended recipient. “Maybe it’s the NSA that has created a fake public key linked to you, and I’m somehow tricked into encrypting data with that public key,” he told Fortune. In the security space, the tactic is known as a “man-in-the-middle attack,” like a postal worker opening your bank statement to get your social security number and then resealing the envelope.
Blockchains are an immutable ledger, meaning any data initially entered onto them can’t be altered. Yen realized that putting users’ public keys on a blockchain would create a record ensuring those keys actually belonged to them – and would be cross-referenced whenever other users send emails. “In order for the verification to be trusted, it needs to be public, and it needs to be unchanging,” Yen said.
Curious if anyone here would use a feature like this? It sounds neat but I don’t think I’m going to be needing a feature like this on a day-to-day basis, though I could see use cases for folks handling sensitive information.
Right here:
The benefit of doing this with a blockchain instead of a privately held and maintained database is that the latter can be compromised, and you just have to trust “whoever” is maintaining that private database. Blockchain means that the ledger is distributed to many nodes, and any post-entry modification to that chain would be instantly recognized, and marked invalid by the other nodes operating the chain. Besides that, when you’re looking up a public key for a recipient on such a blockchain, you would be looking it up at a number of nodes large enough that in order for a malicious entry to come through, they would all have to be modified in the same way, at the same time, and you would have to be asking before the change got flagged. Poisoning blockchain data like this is simply not possible; that’s what makes this an especially secure option.
But it’s not public. It’s a private blockchain. The immutable ledger aspect only matters if everyone can see the ledger. Otherwise we take at face value all of the things you said. Assume they run one node and that one node is compromised by a malicious actor. The system fails. Extend it to a limited number of nodes all controlled by SREs and assume an SRE is compromised (this kind of spearphishing is very common). The system fails again.
Sure, you can creatively figure out a way to manage the risks I’ve mentioned and others I haven’t thought of. The core issue, that it’s not public, still remains. If I’m supposed to trust Proton telling me the person I’m emailing is not the NSA pretending to be that person (as the Proton CEO suggested), I need to trust their verification system.
It’s. In. Beta. Of course it’s not being offered to the general public yet. It’s likely that there are very many beta nodes, in order to test scalability. When it’s out of beta, you drop the beta chain and start a new one.
Did we read the same article? Emphasis mine.
I’m not interested until it’s public. Additionally, building out the chain then dropping it to rebuild a new public one is rewriting history, which violates the whole “immutable” part of “immutable ledger.”
Context matters:
It’s not rewriting history. We’re talking about validation of public keys. The exact same information can be added to a public non-beta chain, to satisfy the concerns about security that would come from maintaining a previously private beta chain into production.
… which gives a timing attack and the ability for bad actors to impersonate someone. I agree with you that, once public, this is a good idea. You cannot convince me that this is a good idea if done privately because there is no way to trust but verify, especially in the highly sensitive contexts they want trust in.
If it’s not public, I won’t trust it. You trust it blindly because it’s in beta. We’re not going to come to an agreement over these mutually exclusive positions.
I don’t “trust it blindly” because it’s in beta - I understand that it’s a work in progress because it’s in beta. Jesus christ you people and your fucking tinfoil hats.
Your only response to valid criticism about the lack of verification is pointing to the state of development as if that magically washes away all of the criticism. It doesn’t.
While I do have many tinfoil hats, basic fucking trust measures do not require me to pull them out. This is cryptography 101 shit not anything complicated.
“Hey, I’m making a cake, I think you’ll like to have a piece when it’s done!”
NO WAY AM I EATING THAT RAW BATTER WITH UNCOOKED EGGS IN IT YOU’RE EVIL
This is why you’re not one of the beta testers.
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As long as there is an appropriate method for adding a legitimate entry to the chain, incorrectly entered data can be handled by appending corrected data on to the chain, and marking the error as such. Sensitive data, in this case, would be along the lines of “I accidentally added my private key instead of my public key.” The action necessary here is the same as if I published my private key anywhere: stop using that key pair and generate a new one.
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This part:
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Well, if there’s not, then the whole thing would never work at all.
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https://finance.yahoo.com/news/blockchain-not-crypto-proton-mail-120000573.html
No. That’s not how that works. Just because a blockchain is “private” doesn’t make it suddenly changeable, and it doesn’t mean there’s a unsafely small number of nodes. People commonly get invited to participate in beta testing; that’s kind of how software development works.
Remember when I said:
That hasn’t become untrue in the last hour.