Building Certifications Paths: Forward vs. Reverse

In general, building and validating a certification path connecting a trust anchor to a target can be a very timeconsuming process. As such, any optimizations are valuable. Certification paths are commonly built from the target to the trust anchor (“building in the forward direction”) or from the trust anchor to the target (“building in the reverse direction”). This paper presents a comparison of these two approaches, analyzes the advantages and disadvantages of each approach, and concludes that building in the reverse direction is often more effective than building in the forward direction.