A portable encryption key installation system is disclosed that includes a portable keying device for installing a data communications encryption in an electronic terminal. The portable keying device securely reprograms the encryption key in the electronic terminal without having to remove the terminal from its shipping container or ship the electronic terminal off-site. Furthermore, the portable keying device securely reprograms the encryption key in the electronic terminal without having to dismantle the terminal, de-activate any anti-tampering features, or re-bond the terminal.