Many users – myself included – would like the security of having everything they do on a web service encrypted. That is, they don't won't any one at the web service to be able to look at their: posts, info, tasks, etc...
This is also major complaint in this discussion of an otherwise cool service: http://news.ycombinator.com/item?id=1549115
Since this data needs to be recoverable, some sort of two-way encryption is required. But unless you're prompting the user for the encryption key on every request, this key will need to be stored on the server, and the point of encrypting the data is basically lost.
What is a way to securely encrypt user data without degrading the user experience (asking for some key on every request)?
-- UPDATE --
From @Borealid's answer, I've focused on two possibilities: challenge-response protocols, where no data (password included) is sent in the "clear", and non-challenge-response protocols, where data (password included) is sent in the "clear" (although over HTTPS).
Challenge-response protocols (specifically SRP: http://srp.stanford.edu/)
It seems that its implementation would need to rely on either a fully AJAX site or using web storage. This is so the browser can persist the challenge-response data during encryption and also the encryption key between different "pages". (I'm assuming after authentication is completed I would send them back the encrypted encryption key, which they would decrypt client-side to obtain the real encryption key.)
The problem is that I'm either:
- fully AJAX, which I don't like because I love urls and don't won't a user to live exclusively on a single url, or
- I have to store data encryption keys in web storage, which based on security encryption cryptography rsa server-side