How will Gmail be able to detect SPAM and display ads when emails are encrypted end-to-end?

Question

Context

Google is making end-to-end encryption easier to use.

SPAM

How will they be able to perform SPAM detection when the email is transmitted and stored encryptedly?

I suppose that if the SPAM email sent to everybody has the identical body, then the encrpyted text will be identical, so it can easily be identified as SPAM once people start flagging it as such.

But even if only one bit is different, the whole encrypted text will be different. What ways are there to detect SPAM emails then?

Advertisement

How will displaying ads work, when the email is only decrypted in the user's browser, i.e. locally?

Use client-side code to parse the email once it's decrypted, send keywords to the server and fetch ads to display?

Answer 1

The answer to the first part of your question is the current Gmail spam filters would not be as effective, they could read the header information and block certain sender addresses but they could not read the actual message. Your assumption that all the encrypted spam message bodies would be identical is incorrect, every individuals public key would produce a different message body even though the original message content is identical.

As far as advertisement is concerned the ads served to you would not be as individually tailored to you, there is already an option to opt out of user specific ads. If the client where configured to send back keywords to Google to serve up individual tailored ads it would be a major privacy violation, hopefully the extensions/plugins they promote are open-source and open to scrutiny.