Keychain is an extremely handy OpenSSH, commercial SSH2-compatible
RSA/DSA and GnuPG key management application. It acts as a front-end to
the agents, allowing you to easily have one long-running agent process
per system, rather than per login session. This dramatically reduces
the number of times you need to enter your pass phrase from once per
new login session to once every time your local machine is rebooted.