An electronic control unit (ECU) for vehicles is described, including memory to store encrypted data and unencrypted data; a main control unit operatively connected to memory to access unencrypted data; and a hardware encryption-decryption device operatively connected to memory to access encrypted/decrypted data for decryption using a hardware algorithm and for encryption using a hardware algorithm. Data in the memory is decrypted by the hardware encryption-decryption device using the hardware algorithm and stored in memory for use by the main control unit. Data in memory is encrypted by the hardware encryption-decryption device using the hardware algorithm for storage in memory. The main control unit and the hardware encryption-decryption device are separate integrate circuits on a same substrate or and are connected by a bus and can process data in parallel. An external bus can communicate encrypted information with the ECU to allow encrypt/decrypt at run time (on-the-fly) and wire-speed.