alt Hacker NewsIt's a shame that now, where S/MIME is a feature of pretty much every mail app, noone uses it outside of businesses. Opportunistic encryption between mail servers isn't good enough.
We really need a CA that does for mail what Let's encrypt has done for HTTP:
The CA needs to provider proper S/MIME certificates:
- free like Let's Encrypt
- duration of 1 year or longer and
- users generate their own keys
Replies
Why such a long lifetime?
If you could actually solve the deeper problem of the sender being able to find the correct certificate to use for the recipient(s), then the lifetime could and should be as short as possible, as in days not years. The recipient can decrypt the message forever, as long as they continue to possess the private key, even if the associated certificate expires. Short-lived certificates are the only effective mechanism for dealing with key theft and mis-issuance that works at scale.
> duration of 1 year or longer
Let's Encrypt is bringing the duration of certs down not up. I believe their goal is 30 minutes validity.
The problem with email encryption is not about CAs or verification of keys at all. The problem is key management and how encryption interferes with the common expectations that users have about email. In a corporate environment it is easier because the corporation itself can manage user keys and issue yubikeys etc., but for individual users there is no such support. It is also clunky to have to first receive someone's public key before you can send an encrypted message; for chat apps that is not a problem because chat is interactive and typically real-time, but with email there is no guarantee about interaction.
Those issues are partially addressed with "identity based encryption," but IBE always has a "backdoor" because there is a party that issues the users' private keys (and hence can always read a users' messages). On the other hand IBE does allow you to "just send" an email to someone because the public keys are just the "identities" (e.g. email addresses) combined with a single master public key. Key management is not as much of a problem because of how keys are generated. IBE does have some users, but as you said it is mostly business/organizational use.