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.
What are the tradeoffs, assuming an email encryption scheme based on self custodied private keys and publicly published public keys? I don't see any major disadvantages to using blockchain for this, and significant advantages. It's a big deal if no one can selectively remove/conceal previously published info. If associating a key with an email, and someone is trying to impersonate you, you'll know it, it's not going to be hidden from you and specifically shown to someone else. It just makes sense to do it that way. Yes, you have to trust something at some point, but this is a way to minimize how much trust you have to give.
But that is necessarily the case given what they are trying to do to begin with. Why don't you want to acknowledge that? What you're saying is not an argument that blockchain would not accomplish the goal set out here, it's an argument against using public key cryptography for email where the users hold the private keys.
What makes you think that? If an impersonator published an association between your name/email and their public key to a blockchain, everyone can necessarily see it, including you. You have the opportunity to let people know through various channels which records are or are not legitimate.
As for DMARC,
I'll admit I don't know a ton about the inner workings of DNS, but I know that DNS hijacking is very common in high stakes scenarios like cryotocurrency application frontend websites, and essentially out of the hands of the victim to be able to protect their control of a domain. With a system strictly requiring access to private keys, no hijacking is happening without stealing those keys from the user.