A system, peripheral device, and method for authenticating an encryption key before transmitting encrypted messages containing sensitive information are provided. Authentication of a client device during the coordination of data transfer among multiple computer devices is possible by providing a peripheral device that does not have a direct connection to a network, but rather, any message to be transmitted over the network must be relayed through a client device. Any sensitive information to be transferred to a remote device is inserted into a message, then the message is encrypted in the peripheral device. This prevents any process running on the client device from fooling the client device into communicating confidential information to a third party rather than the desired remote computer, because the client device never sees the sensitive information in an unencrypted form; only the peripheral device has access to the sensitive information in an unencrypted form.