Certificate Authority (CA)

• A Certificate Authority (CA) is a trusted entity that issues digital certificates.
• CAs verify the identity of entities requesting a certificate.
• CAs play a crucial role in establishing trust in online communications.
• CAs use public key infrastructure (PKI) to manage digital certificates.

Extended Validation Certificates

• Extended Validation (EV) certificates provide a higher level of trust compared to standard certificates.
• CAs perform a more thorough validation process for EV certificates.
• EV certificates display a green address bar in web browsers to indicate a secure connection.

Registration Authority

• A Registration Authority (RA) assists a CA by verifying the identity of certificate applicants.
• RAs act as intermediaries between the CA and the certificate requestor.
• RAs streamline the certificate issuance process.

Web of Trust

• Web of Trust is a decentralized trust model where users vouch for each other's identities.
• Users sign each other's digital certificates to establish trust relationships.
• Web of Trust is commonly used in email encryption systems like PGP.

Digital Certificates

• Digital certificates are electronic documents that verify the identity of an entity.
• Digital certificates contain information such as the subject's name, public key, and the CA's signature.
• Digital certificates are used to establish secure communication channels.
• Digital certificates are the primary vehicle by which trust is disseminated across the internet.
• Digital certificates bind a public key to an identity.

Certificate Revocation List

• A Certificate Revocation List (CRL) is a list of revoked digital certificates.
• CAs issue CRLs to inform users about certificates that are no longer valid.
• Browsers and other applications check CRLs to verify the validity of certificates.
• CRLs are a means of combating compromised keys.

Online Certificate Status Protocol

• Online Certificate Status Protocol (OCSP) is an alternative to CRLs for checking certificate status.
• OCSP allows applications to query a CA in real-time to determine if a certificate is valid.
• OCSP is generally faster and more efficient than CRLs.
• OCSP reduces the performance overhead of checking certificate validity.

X.509

• X.509 is a standard for digital certificates.
• X.509 defines the format and content of digital certificates.
• X.509 is widely used in PKI systems.

Root Certificate

• A root certificate is a self-signed certificate issued by a CA.
• Root certificates are the foundation of trust in a PKI hierarchy.
• Root certificates are typically distributed with operating systems and browsers.
• Root certificates are inherently trusted.

Intermediate Certificate

• An intermediate certificate is issued by a CA that is not a root CA.
• Intermediate certificates form a chain of trust between the root CA and the end-entity certificate.
• Intermediate certificates provide flexibility in managing certificate hierarchies.
• Intermediate certificates can delegate trust in a more granular fashion.