A simple way for users to encrypt their files client-side, and send it to the server.

I cooked this up in a few hours as an attempt to learn more about cryptography. The general idea is that ALL encryption is done on the user's browser, leaving absolutely nothing to the server to "snoop around" for.

Hosting requirements

You will need pecl/xattr and redis extensions installed, as well as a redis deployment itself.

Limiting file size

In upload.php

Change:

$megabytes = x * 1048576

x, where X is the amount of megabytes you wish to be the file size limit. Don't forget to check php.ini for the upload size limit also!