Digital Certificates and IT Security

What is a Digital Certificate?

• A file containing a public key and a digital signature.
• Acts like a digital identification card.
• Provides authentication and trust in IT security.

Importance of Trust in IT Security

• Allowing someone access based on username and password requires trust.
• Digital certificates help establish this trust.
• Certificate Authority (CA) can sign a certificate to validate trustworthiness.

Methods to Provide Trust

• Centralized Certificate Authority: Trusted entity signs certificates.
• Web of Trust: Multiple individuals sign each other's certificates.

Certificate Formats

• X509 Standard: Universal certificate format used by web browsers.

Information Contained in Digital Certificates

• Serial number, version, signature algorithm.
• Issuer and holder information.
• Public key and other attributes.

Establishing Trust with Unknown Entities

• Browser verifies certificates through CA.
• CA acts as a root of trust.
• Trust is established if the CA is trusted by the browser.

Creating a Digital Certificate

• Use a public key and identifying information to create a Certificate Signing Request (CSR).
• Send CSR to CA for validation and digital signing.
• CA's validation process is crucial for trust.

Internal Certificate Authorities

• Organizations can create their own CA for internal services.
• Requires installation of CA software and public certificates within the organization.

Wildcard Certificates

• Allow a certificate to be valid for multiple subdomains of a domain.
• Useful for administration and distribution across devices.

Certificate Revocation

• Certificate Revocation List (CRL): Lists revoked certificates.
• Heartbleed Attack: Example of why revocation is necessary.

Online Certificate Status Protocol (OCSP)

• More efficient than CRLs.
• Status of certificates checked during SSL handshake (OCSP stapling).
• Digital signature by CA validates the status.

Browser Support for OCSP

• Most modern browsers support OCSP.
• Important to check if browsers perform proper validation.

Key Takeaways

• Digital certificates are essential for establishing trust in digital communications.
• Understanding the role and processes of certificate authorities is crucial for IT security.
• Efficient certificate revocation and validation processes are vital for maintaining secure connections.