Nice tool! I like the way you simply validate the signature on the end-server!<p>One feature that I think would be nice to have, is to include an expiry option (I know that some similar tools had an option where you could make the text/note expire after it has been read or other where it was kept for let's say 30days).
For anyone interested in how things work under the hood, I wrote a brief summary here: <a href="https://eric.mann.blog/end-to-end-encrypted-secret-sharing/" rel="nofollow">https://eric.mann.blog/end-to-end-encrypted-secret-sharing/</a>