What you probably really want to do is to use the ssh-keygen command to generate a key pair, and use the public and private keys to authenticate without passwords.

There is a super-brief how-to at http://hkn.eecs.berkeley.edu/~dhsu/ssh_public_key_howto.html. For more detail, look at the output of man ssh-keygen (and man ssh). You could also google for ssh-keygen and the name of the SSH package you are using (OpenSSH, PuTTY, Tectia, etc).