Danni-Tech

Key Points from This Video on Certificate Authorities and Their Role in Trust:

• The Purpose of PKI:

  • The goal of a Public Key Infrastructure (PKI) is to establish trust in digital communications.
  • Trust starts at the root—with the Root Certificate Authority (CA), the foundation of the entire certificate chain.

• Root Certificate Authority (Root CA):

  • The Root CA holds its own public and private key pair.
  • It issues a self-signed certificate, which serves as the starting point of trust.
  • This self-signed certificate is pre-installed in most web browsers, meaning it’s automatically recognized as the base of the chain of trust.

• Intermediate Certificate Authorities (Intermediate CAs):

  • Positioned below the Root CA in the chain.
  • Each Intermediate CA:
    1. Generates its own public-private key pair.
    2. Sends a Certificate Signing Request (CSR) to the CA above it for approval.
  • This structure ensures that each certificate is signed by the one directly above it, forming a continuous chain of trust back to the Root CA.

• The Certificate Chain:

  • Root CA → Intermediate CAs → Web Server
  • While there can be multiple intermediate CAs, they all trace back to the trusted Root CA.
  • The Web Server sits at the end of the chain, with its certificate issued after sending a CSR to the CA directly above it.

• Subjects and Issuers:

  • Each certificate in the chain contains information about:
    1. The Subject: The entity the certificate is issued to (e.g., bluekeys.com).
    2. The Issuer: The CA that issued the certificate (e.g., Gold ICA for bluekeys.com).
  • Exercise: Identify the subject and issuer for each certificate in the chain, leading back to the Red Root Certificate Authority.

• What Happens When a Client Connects to a Server?

  • The client’s browser already has the Root CA certificate installed.
  • When connecting to a server, the server sends:
    1. Its own certificate.
    2. The full chain of certificates, including intermediate certificates, to prove trust back to the Root CA.

• How Trust is Verified:

  1. The client uses the Root CA’s public key (already installed) to validate the signature on the Green Certificate.
  2. It then uses the Green Certificate’s public key to validate the Gold Certificate’s signature.
  3. Finally, the Gold Certificate’s public key is used to validate the Blue Certificate’s signature.
  • This step-by-step verification confirms that every certificate in the chain is legitimate, ultimately linking back to the trusted Root CA.

• Key Takeaways:

  1. Root CA: The foundation of trust in PKI, with a self-signed certificate pre-installed in browsers.
  2. Intermediate CAs: Bridge the trust between the Root CA and the end-entity (server) certificates.
  3. Chain of Trust: Each certificate is signed by the CA above it, creating a path that can be traced back to the Root CA.
  4. Client Verification: The client checks each certificate in the chain to confirm the server’s identity and ensure secure communication.