ssh-keygen -t dsa and follow the prompts. If you're going to use the shared key to log into a system where user identities shouldn't be shared (i.e iVEC) save the key file as something like
/home/observer/.ssh/id_dsa_username_galaxy, and use a non-blank passphrase
scp .ssh/id_dsa_username_galaxy email@example.com:
.ssh/authorized_keys file with a command like
cat id_dsa_username_galaxy » .ssh/authorized_keys
ssh-agent bash and
ssh-add .ssh/id_dsa_username_galaxy. You'll have to enter your passphrase once this way.