Understanding Public-Key Infrastructure: Concepts, Standards, and Deployment Considerations

X.509 Versus Alternative Certificate Formats

As discussed in Chapter 6, "Certificates and Certification," alternative certificate formats to the X.509 Version 3 public key certificate exist. Not surprisingly, there are proponents of each format. For example, proponents of the Simple Public Key Infrastructure (SPKI)—as discussed in Chapter 6—would suggest that the SPKI certificates are attractive because they focus on the notion of roles and authorizations, rather than identity. Further, a Pretty Good Privacy (PGP) or OpenPGP advocate might claim that PGP certificates are more flexible than X.509 Version 3 public-key certificates and that they are more suitable for establishing trust relationships among individuals.

Although some of these alternative ...