Is there any way to decrypt tor traffic from an exit node or relay? I know it's possible to analyze the traffic using something like tcpflow or tcpdump, but it comes back as encrypted giberish. Is there any way to decrypt it?
If you sniff on the exit node and the connection is not https/hidden service, then you will have the traffic in clear but you will not be able to know from who it came. Unless the traffic itself is revealing the identity.
In other cases, as far as we know, you can't decrypt tor. As other said, tor will be useless if it was possible.