For text (not for files) you can encrypt on the client side using JS (a fine library: http://crypto.stanford.edu/sjcl/ http://crypto.stanford.edu/sjcl/ ) before

For text (not for files) you can encrypt on the client side using JS (a fine library: http://crypto.stanford.edu/sjcl/ http://crypto.stanford.edu/sjcl/ ) before uploading to the server, this is what I do in https://whisperpassword.com/ https://whisperpassword.com/