Patent ID: 6272637
Filing Date: 2001-08-07
Classification: G06F,G11C

Abstract:
A system including a first circuit with an internal bus, said first circuit being capable of communicating with a second circuit via a data bus and an address bus, said second circuit including an external memory block, said system comprising:a detector for detecting an uncompensated system reset;means for determining whether said detected uncompensated system reset includes an attacking uncompensated system reset, said means for determining further for determining whether said uncompensated system reset was initiated responsive to an environmental condition, thereby indicating that said uncompensated system reset includes a non-attacking uncompensated system reset;a storage device connected to said detector, said storage device including a system reset indicator value, wherein said system reset indicator value is indicative of a number of detected attacking uncompensated system resets;means for incrementing said system reset indicator value included in said storage device responsive to detecting said uncompensated system reset and responsive to determining that said detected uncompensated system reset is said attacking uncompensated system reset;means for launching an evasive action responsive to said system reset indicator value being equal to or greater than a threshold;a secure memory block, disposed within said first circuit, said secure memory block being coupled to said internal bus;an address path encryptor for encrypting signals asserted on said address bus using the contents of a first encryption key, said address path encryptor being coupled to said internal bus;a data path encryptor for encrypting signals asserted on said data bus using the contents of a second encryption key, said data path encryptor being coupled to said internal bus; anda power input;wherein said means for determining whether said uncompensated system reset was initiated responsive to an environmental condition comprises:means for monitoring said power input to determine whether an uncompensated system reset is initiated responsive to a power fluctuation, wherein the power fluctuation is associated with a power fluctuation frequency and wherein said means for monitoring is configured to monitor said power fluctuation frequency.