Patent ID: 7653820
Filing Date: 2010-01-26
Classification: G06F

Abstract:
1. A system of securely using decryption keys during configuration of an integrated circuit having programmable logic, comprises: a microcontroller within the integrated circuit for receiving an encrypted bitstream; a key storage register coupled to the microcontroller for storing key data; a decryptor coupled to the key storage register, wherein only the decryptor reads from the key storage register; and a configuration data register in the integrated circuit, wherein the configuration data register is readable by the microcontroller before the decryptor is used and the configuration data register cannot be read by the microcontroller after the decryptor is used, wherein the decryptor is a software decryptor stored in a memory and executed by the microcontroller, wherein the system further comprises hardware, independent of the microcontroller, that allows the microcontroller access to the key storage register by unblocking a signal path coupling the microcontroller and the key storage register when a program counter of the microcontroller specifies an address within an address range corresponding to the software decryptor within the memory and disallows the microcontroller access to the key storage register by blocking the signal path coupling the microcontroller and the key storage register.