PKI and Certificate Authorities: Who Vouches for the Public Key?
PKI solves a trust problem: knowing a public key is useful only if you can trust whose key it actually is.
Digital certificate
A digital certificate binds identity information to a public key and includes issuer and validity information.
Certificate authority
A trusted certificate authority validates according to its procedures and digitally signs certificates so relying parties can verify the issuer's attestation.
Trust chain
Systems can validate a certificate through intermediate and root certificate authorities, checking signatures, expiration, revocation, and other policy requirements.
Exam strategy
Do not confuse encryption with identity validation. The certificate helps establish whose public key you are using; cryptographic protocols then use the key for authentication or secure communication.
The takeaway
PKI uses trusted certificate authorities and signed certificates to bind identities to public keys.
Related Summit resources
FAQ
Does a digital certificate contain a public key?
Yes.
What does a certificate authority do?
It validates and signs certificates under its trust framework.
Why is the trust chain important?
It lets systems verify the certificate back to a trusted authority.