  The Strict Avalanche Criterion (SAC) is a measure of both confusion and
diffusion, which are key properties of a cryptographic hash function. This work
provides a working definition of the SAC, describes an experimental methodology
that can be used to statistically evaluate whether a cryptographic hash meets
the SAC, and uses this to investigate the degree to which compression function
of the SHA-1 hash meets the SAC. The results ($P < 0.01$) are heartening: SHA-1
closely tracks the SAC after the first 24 rounds, and demonstrates excellent
properties of confusion and diffusion throughout.
