In SSH the client publishes his public encryption key into the server authorized_keys file for a given user. I am interested in understanding better how the public key is used context of authentication. At which stage is it used? Are there digest messages being exchanged? I Googled it and found no clear answer to this questions. Thanks!
The SSH protocol is described in excruciating detail in a series of five RFCs:
The authentication protocol is RFC 4252 (http://www.snailbook.com/docs/userauth.txt).
If you're interested in seeing what SSH is sending back and forth, you can run it with the
-v parameter to see what it's doing.