I've been using sbd to compare it with Ncat. Ncat offers SSL with or without certificates. sbd offers
AES-CBC-128, with an option to override the "default phrase to use for encryption".
sbd -h ... -c on|off encryption on/off. specify whether you want to use the built-in AES-CBC-128 + HMAC-SHA1 encryption implementation (by Christophe Devine - http://www.cr0.net:8040/) or not default is: -c on -k secret override default phrase to use for encryption (secret must be shared between client and server)
This looks like a default encryption key is hardcoded into sbd. Is this true? If so, would using this default secret make it possible to reverse the distributed binary, find the key, then reassemble TCP streams of sbd sessions and decrypt them?