is client based online encryption practical?

Question

I'm wondering whether a mechanism exists that allows client to client encryption. For example, when enabled, any information that is entered on one client can only be decrypted using a specific key.

Similar to how regular public key transactions work, but server agnostic.

A use case:

Everything on my Facebook profile is encrypted, and no body would be able to view that information (not even facebook). The users that I give the key would be able to decrypt that information.

This would allow complete control of data stored online.

The same idea can be applied for pictures uploaded to the internet.

One issue that I see is to have a practical mechanism to manage keys and a secure way to distribute keys to other users.

Has anyone done something like this before?

Answer 1

In case of Facebook I can imagine encrypting the data with OpenPGP keys into armored (text) format. Then you can place encrypted block to facebook or anywhere else. Other users would take the block, decrypt it on the client side and see it.

The same applies with other social networks and places where you can store some text block.

You can easily do encryption in some client application and even in Javascript (if you manage to make JavaScript load local user's keys somehow).