None
compares two similarity digests and outputs a score. The
recommended approach is to assign a score s in the 0 ≤ s ≤ 1 range, where 0 indicates no similarity and 1 indicates high similarity. This score represents a normalized estimate of the number of matching features in the feature sets corresponding to the artifacts from which the similarity digests were created.
Source(s):
NIST SP 800-168