Critical Message Integrity Over A Shared Network
Cost and efficiency concerns can force distributed embedded systems to use a single network for both critical and non-critical messages. Such designs must protect against masquerading faults caused by defects in and failures of non-critical network processes. Cyclic Redundancy Codes (CRCs) offer protection against random bit errors caused by environmental interference and some hardware faults, but typically do not defend against most design defects. A way to protect against such arbitrary, non-malicious faults is to make critical messages cryptographically secure. An alternative to expensive, full-strength cryptographic security is the use of lightweight digital signatures based on CRCs for critical processes. Both symmetric and asymmetric key digital signatures based on CRCs form parts of the cost/performance tradeoff space to improve critical message integrity.