Public Key Infrastructures - PGP vs. X.509

Reliance on electronic communications makes information more vulnerable and users require confidentiality, message integrity, sender authentication and sender non-repudiation. Public key cryptography provides these services. The goal of a Public Key Infrastructure (PKI) is to enable secure, convenient and efficient discovery of public keys. There are various types of PKI that are deployed. They differ in the certificate format, trust rules and configuration. In this article systems with X.509 and PGP certificates are described, with their advantages and disadvantages. The goal of this analysis is to highlight the differences between both systems and to provide the reasons for their usage.