[syslog-ng] encrypt syslog-ng messages

I've setup syslog-ng on a log server and it's successfully receiving log messages from various clients. I want to encrypt the messages, so I used SSH tunnels and stunnel. However, in both of those cases, syslog-ng sees the message as having originated from itself, rather than from the real sender. Is there a way to fix this, or is there a different way to encrypt the messages? Thanks for your help, syslog-ng's awesome. -Shaun