Tailored Health Tests for Physical Entropy Sources (N13a)
Health tests are an integral part of entropy sources. These tests are critical for ensuring security, because noise sources can be sensitive to process variation in manufacturing, component aging or damage, and varying environmental conditions, all of which may cause the output quality to deteriorate. Since entropy degradation will not cause interoperability problems or lead to visibly-bad DRBG outputs, noise source failures can only be detected within the entropy source. To be effective, health tests must be adapted to the noise source. This talk will discuss current and future requirements for health tests in SP 800-90B and for online and total-failure tests in AIS 20/31, including the goals of health testing, the different kinds of failure that must be tested for, testing raw data vs conditioned bits, the role of the NIST-defined tests RCT and APT, and designing health tests tailored to the stochastic model of a physical noise source.