I'm referring to this cryptographic property: https://en.wikipedia.org/wiki/Deniable_authentication https://en.wikipedia.org/wiki/Deniable_authentication which

I'm referring to this cryptographic property: https://en.wikipedia.org/wiki/Deniable_authentication https://en.wikipedia.org/wiki/Deniable_authentication which means that once a message is received you cannot re-authenticate it, so evidence on any device is no better than with unencrypted messaging. This is in contrast with classic public key authentication like PGP which provides further evidence that the message is legit and was indeed sent by who it says.