Computer architecture for a handheld electronic device with a shared human-machine interface

Abstract

Mobile PDA computer system () includes a secure user processor (), a non-secure user processor (), a cryptographic engine (), and a shared human/machine interface (HMI) (). The secure user processor () can be comprised of a first trusted microprocessor and a first trusted operating system executing on the first trusted microprocessor. The non-secure user processor () can be comprised of a second non-trusted microprocessor and a second non-trusted operating system executing on the second non-trusted microprocessor. A cryptographic engine () can be comprised of a third trusted cryptographic processor and a third trusted operating system executing on the third trusted cryptographic processor. The cryptographic engine can be configured for encrypting and decrypting data. A first data communication link () communicates data between the secure user processor and the cryptographic engine. A second data communication link () communicates data between the cryptographic engine and the non-secure user processor. In this way, the cryptographic engine forms a bridge between the secure user processor and the non-secure user processor. An HMI () comprised of trusted hardware for user input and output is time-multiplex-shared among the secure user processor (), the non-secure user processor (), and the cryptographic engine () in a secure fashion.