You will find an elegant solution to your problem at http://www.gentoo.org/proj/en/keychain.xml
I use the keychain to connect through three linux boxes using the ssh protocol.
You will also find a link to a series of articles that describe the keychain and explains the ssh protocol.
It is essential that you read these articles before installing the keychain. You must understand the underlying mechanism otherwise you could compromise the security of your system.
However, once read and understood you will find the keychain is quite straight forward to install and use. To date I have had no problems using the keychain but then I work in restricted environment.
As with all advice - proceed with caution and at your own risk.