What this is
This is software for securely sharing files over the
internet. It supports encrypting and decrypting files in the browser
such that their contents are never seen by the server. All files
uploaded expire after a configurable amount of time to help make
sure your data isn't sitting on the internet forever. The software
also supports performing encryption and decryption server-side when
JavaScript is unavailable. The information required to view file
contents is only stored for the duration of the
encryption/decryption process, but this is less secure than
performing encryption/decryption in-browser with JavaScript.
What this is not
This is not a magic spell that will instantly guarantee the perfect
security of the data you share using it. The software is designed to
protect your uploads while it stores them, but has no power over
data that has left the service. If you share an upload with someone,
there is nothing stopping them from re-uploading it somewhere else
against your wishes. It is also not impossible that a bad actor
could compromise this software in order to steal sensitive
information. In short: if you want the best possible security, you
cannot trust any third party. Anyone who tells you otherwise is
lying to you, intentionally or not.