A secure computer keyboard system utilizes a mobile device in conjunction with a keyboard device to provide secure keyboard entry in a public place. An application on the mobile device produces a mapping of characters to character codings, and displays to the user a key such as a modified keyboard showing the mapping. The keyboard device receives input keystrokes from the user representing the codings and transmits the keystrokes back to the mobile device or to a server. The mobile device or server decodes the keystrokes using the mapping.