onereplyac

Totally agree... it is just disappointing that services like Skiff advertise total E2EE to unsuspecting users with no mention of this in their marketing, luring users into a false sense of security

Free marketing at the expense of user trust

Unfortunately not even close. When the server gets the email it is not encrypted (unless the sender has a skiff address too, which is a very tiny portion...). And when you send an email to anyone outside skiff it is the same problem, the email has to be unencrypted so the server can send it in a form readable by the recepient. Without anything like PGP the server does not know the reciepent's public key, so it is impossible to encrypt it.

The encryption happens after the server recieves the plaintext email and passes it to the client...

Normal email proiders don't dowbload all emails whenever a user logs into a new device

That's all moot though, since your server has access to plaintext emails when sending and recieving (99.99999% of email addresses would be outside skiff), which completely subverts the whole point of encryption. A vulnerability on the server could leak all user emails, without needing their keys.... This is a solution theoretically only as strong as encryption at rest.

Depends, on an older phone, downloading all emails just to allow for searches locally won't be very efficient. Log out also becomes a problem, if emails are stored on one device that gets stolen, adversary now has access to the local index since all the keys or on the device usually with no FDE. Meanwhile with gmail a log-out would clear all traces instantly.

Except there is a reason. Encrypting email has very little to no benefit, since it is transmitted in plaintext and usually stored in plaintext on the recipient's side, your emails almost always exist in unencrypted form. On top of that it has major usability drawbacks, for example you cant ask the server to search emails for you anymore - all emails have to be downloaded on all your devices to be able to search - which is what skiff does. It will be okay at the start, and progressively get slower and use more space on your drive the more you use it.

From the whitepaper, it seems search is done by downloading all emails on every device to index them locally. Curious how well this works with a large amount of emails?

It really is not backed by cryptographic security at all. Since your server has access to plaintext emails when sending and recieving (99.99999% of email addresses would be outside skiff), which completely subverts the whole point of encryption. A vulnerability on the server could leak all user emails, without needing their keys.... This is a solution theoretically only as strong as encryption at rest.