Communication will be done by lawyers and subject to strong confidentiality protection, no one will ever know.
Basically, exactly how it happens with kidnappings today.
It's literally illegal to pay certain sanctioned organizations today for kidnappings - because they are designated terrorist orgs.
Who negotiates the ransom? Lawyers and security firms, been going on for a long long time.
Amusingly enough, this has even gone through courts in some places, you might wanna look up caselaw. They just decided to classify kidnappers as "criminals" for the ransom purposes, or some other such wordsmithing.
In the US these laws are simply ignored outright.
"The United States Code prohibits funding terrorist organizations, which includes the payment of ransom monies to terrorist organizations.2 However, the outlook in the United States on ransom payments being made to terrorist groups has softened. In June 2015, President Obama announced that private parties may negotiate with and pay ransoms to terrorist groups without fear of criminal prosecution, which has been the informal practice for years. In fact, nobody has ever been prosecuted for paying a ransom in the United States."
Just imagine your election prospects after jailing a mother who paid a ransom to save her child.
Imagine defending a claim that such law is constitutional, moral and just.
this penalizes the victim. Legally this might be impossible for the same reasons the law is unable to stop you from paying a ransom in kidnapping.
I'm not convinced this would affect the problem even if outlawed. Companies would simply go the path of least resistance the same way they do with avoiding tax. There will always be loopholes for shell / shelf companies to hide activities. The ransomware gangs themselves already today encourage you to reach out from private emails and promise smoother negotiation if you do.