ssh will not help you with anything that compromises your host's security in some other way. Once an attacker has gained root access to a machine, they can subvert ssh as well.
If somebody malevolent has access to your home directory, then security is nonexistent. This can occur when your home directory is exported via NFS. You should never place private keys in an NFS mounted/exported directory.
Of all the associated systems technology present under most operating environments, ssh is but one small tool in helping to improve security. You should not believe that merely using ssh will drastically improve security for your local systems, as there may be many other issues that you, or your local analyst, should worry about.
If you have questions about this document, please contact SCD Customer Support. You can also reach us by telephone 24 hours a day, seven days a week at 303-497-1278. Additional contact methods: consult1@ucar.edu and during business hours in NCAR Mesa Lab Suite 39.