Encryption key management system for an integrated circuit

Abstract

A microcontroller is in bus communication with an improved integrated circuit for providing data to the integrated circuit and reading data from the integrated circuit. The integrated circuit selectively processes data by encrypting or decrypting the data. The integrated circuit includes a data register for receiving data from the microcontroller via the data bus and storing the data. A DES key register is also provided for receiving and storing a key (Ks) from the controller via the data bus and a DES control register is provided for receiving and storing control signal from the controller via the data bus. The integrated circuit has a digital encryption engine module for reading the data from the data register and the DES key register in response to specific control signal stored in as DES control register and for processing the data utilizing the key (Ks) and outputting the encrypted data. A second DES key register (Kv) isolated from the data bus stores second key(Kv). A multiplexer is used for selectively enabling the first DES key (Ks) from the DES Key register or the second DES key (Kv) from the second DES Key register in response to the data in the DES control register. In addition, a internal key register stories an internal key (Ki) and a results register is provided for storing the processed data and directing the processed data to the data bus. A demultiplexer is for receiving the processed data from the DES engine and directing the processed data to the internal key register or the results register allow as a further alternative use of the internal key to encrypt or decrypt data.