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.
And on the flip side, you cannot delete data that is sensitive or entered incorrectly. Blockchain evangelists assume these things will never happen.
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.
So at the point a private key becomes compromised, then what? If you have to start from scratch, then a malicious entity could start from scratch too. And if that’s the case, there is no security benefit.
This part:
And if there’s not, then…? Because that was my question.
Well, if there’s not, then the whole thing would never work at all.
Seems like we have found a problem.
Because the Proton blockchain is currently private, the keys they are currently adding could easily be affected by a man in the middle attack. And there would be no way to invalidate those keys for any of the affected users, they would just have to… What?
Ditch their email addresses?
Appeal to a higher authority?
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.
This is patently false. All blockchains are changeable with enough consensus. See something like this article.
Who said it needed to be changed? Proton can simply write invalid data preloaded with their man in the middle attack all ready to go. They don’t need to bother with changing entries, because they can just never enter them to begin with.
Interested parties can, of course, meet in person… But at that point, the blockchain that has been created is both weaker and redundant.
And I’m not sure why you think a non-public, append-only database under the control of a single entity couldn’t be modified. We are approaching levels of “trust me bro” for Proton that were allegedly supposed to be unnecessary. How do you know how many nodes there are? Why not one?