It (deniable authentication) has been provided previously by OTR. https://en.wikipedia.org/wiki/Deniable_authentication https://en.wikipedia.org/wiki/Deniable_

It (deniable authentication) has been provided previously by OTR. https://en.wikipedia.org/wiki/Deniable_authentication https://en.wikipedia.org/wiki/Deniable_authentication TLS provides a weaker version (instead of everyone in the world being able to forge a message, just your peer is able to forge the message).