Issue with spoofing client messages

[Lilyp3892]

I'm trying to overwrite the contents (the string) of a chat message, but I'm not sure how to do it with the new chat verification system (1.19.1) I'm doing this in 1.19.2. My intended outcome is that if you send any message in chat it instead sends a predetermined string in chat possibly just reusing the same verification it generated for that message. If anyone could help me out here that would be great.

[dries007]

You can't, that's the entire point of the chat verification system.

It makes it so it's impossible to change the chat messages from users without "leaving a mark". If you still want to change the text, you have to do it without the signature, and then clients will be able to tell.
I don't know how to do this, I presume just by sending a chat message packet without the signature at all.

IIRC You can't reply messages either, since it uses the previous message in the computation of it's signature. (see reply attack)