X.509 Certificates and PKI
In this chapter, we will learn about X.509 certificates. Certificates are data structures used for identity presentation and verification. X.509 certificates are crucial for the functioning of TLS and TLS-based protocols, such as HTTPS, where certificates are used to prove the identities of websites. Certificates are also used in secure messaging standards, such as S/MIME; VPN solutions, such as OpenVPN; smart cards, software signing, and so on. X.509 certificates can also optionally be used in IPsec.
We will learn about what certificates consist of, how certificate verification chains are built, and how Public Key Infrastructure (PKI) works. In the practical part of this chapter, we will learn how to generate certificates and verify certificate chains on the command line and programmatically using C code.
We are going to cover the following topics in this chapter:
- What is an X.509 certificate?
- Understanding certificate signing chains ...