The link can be stolen by a middle man and there goes your secret, unless you use a passphrase.
It's essentially pastebin with longer links, and automatic deletion when it arrives.
I love the design language though, it's gorgeous.
Make it simpler. Just one, non-scrollable page with just a text-field and a send button would be enough.
cryptography is easy to do wrong and incredibly hard to do correctly. without any source to examine this is just a way to steal your secrets because you can not audit what it actually does, how it does it and if it actually does what it says.