Secure network extension device and method

A method of secure computing using a network extension device, comprising the following steps:

• a. providing an external network;
• b. providing a network extension device having a master CPU, a master memory connected to the master CPU, a protected I/O connected to the master CPU and connectable to one or more local controls and one or more local peripherals, a master trusted device connected to the master CPU, and an external communications port connectable to the external network, wherein the network extension device is known to the external network;
• c. connecting the external communications port of the network extension device to the external network;
• d. after step c, performing an operating mode check;
• e. after step d, causing the network extension device to operate in a mode corresponding to the results of the operating mode check, and performing a security check corresponding to the results of the operating mode check;
• f. after step c, causing the master trusted device to attest the trusted operation of the network extension device to the external network;
• g. in response to receipt by the external network of proper attestation from the trusted device of trusted operation of the network extension device as a result of step f, causing the CPU to function fully, and permitting the network extension device to access the external network;
• and
• h. wherein the network extension device further comprises a traffic encryption module that employs an encryption algorithm and is connected to the master CPU and to the master trusted device, and wherein step f includes a check on the encryption algorithm.