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.
The public part of it would be the RSA pubkey, likely linked with an identifier such as the SHA-256 hash of the email. You could quite easily have that ledger public and it would take millennia to crack any of the emails, much easier to use fuzzing with common words and names than trying wasting computing power for a single email. The whole point of blockchain is that it’s an immutable public ledger which would actually suit this idea quite well.
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This is solving a problem we DO have, albeit in a different way. Email is ancient, the protocol allows you to self identify as whoever you want. Let’s say I send an email from the underworld (server ip address) claiming I’m Napoleon@france (user@domain), the only reason my email is rejected is because the recipient knows Napoleon resides on the server France, not underworld. This validation is mostly done via tricky DNS hacks and a huge part of it is built on top of Google’s infrastructure. If for some reason Google decides I’m not trustworthy, then it doesn’t matter if I’m actually sending Napoleon’s mail from France, it’s gonna be recognized as spam on most servers regardless.
A decentralized chain of trust could potentially replace Google + all these DNS hacks we have in place. No central authority gets to control who is legitimate or not. Of all the bs use cases of block chain I think this one doesn’t seem that bad. It’s building a decentralized chain of trust for an existing decentralized system (email), which is exactly what “block chain” was originally designed for.
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What do you think the problem even is? It sounds like you just don’t understand why someone would want to use public key cryptography to begin with.
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It doesn’t sound like you understand why someone would want to do email with public key cryptography, it sounds like rather you do not like the idea of doing email with public key cryptography. Being unrecoverable is just the tradeoff there. Again, what do you think the problem described even is? For reference,
I think if you actually acknowledge the problem of trust for propagating public keys as a real one that is worth being solved, it would be hard to argue that blockchain is a bad fit for that problem, because it is not. Trustless, verifiable propagation of data is one of the things it actually offers unique benefits for.
It might be useful to start by considering the idea itself and what it is saying, instead of looking for arguments to make against it.
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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.
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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.
I think the main pro of this system would be that it requires no trust. The immutability would be actually a con for privacy: if you’re burned or doxxed later, there would be hard evidence of your identity in the blockchain.
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