It would be interesting if there was a DNS record of some kind to announce a PKI registry for a particular domain's email addresses. This would allow for some kind of decentralized discovery of suitable public keys for individual addressees.
But, a potential sender with important messages still needs do some pre-flight email verification over this path, e.g. sending a verification code encrypted the same way, to validate that the intended user can read it and send it back via another authenticated channel. This ensures that the sender-specific user identity actually possesses control of that email address and the discovered private key. It also reduces the impact of a malicious email provider to only denial-of-service rather than content interception.
So, is that discovery protocol worth it, versus just having an opt-in setting where the user supplies their desired public key and email address in the same form?
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It would be interesting if there was a DNS record of some kind to announce a PKI registry for a particular domain's email addresses. This would allow for some kind of decentralized discovery of suitable public keys for individual addressees.
But, a potential sender with important messages still needs do some pre-flight email verification over this path, e.g. sending a verification code encrypted the same way, to validate that the intended user can read it and send it back via another authenticated channel. This ensures that the sender-specific user identity actually possesses control of that email address and the discovered private key. It also reduces the impact of a malicious email provider to only denial-of-service rather than content interception.
So, is that discovery protocol worth it, versus just having an opt-in setting where the user supplies their desired public key and email address in the same form?