CN

In the context of Public Key Infrastructure (PKI), the Common Name (CN) refers to an attribute within a digital certificate that uniquely identifies a specific entity, typically an individual or a host system. The CN is an essential component of the certificate's subject, helping to ensure proper identity verification and secure communication.

Purpose of the Common Name (CN):

• Identification: The CN identifies the certificate holder, whether it's an individual, organization, or device.
• Trust: The CN helps users and systems verify the identity of the certificate holder before establishing secure communication.
• Matching: When accessing a resource, the CN in the certificate is compared with the hostname to ensure a secure connection.

Usage of the Common Name (CN):

The Common Name is commonly used in:

• SSL/TLS Certificates: In web servers, the CN is often used to match the certificate with the domain name of a website.
• Email Security: CN can be used in S/MIME certificates to verify the identity of email senders and recipients.
• Code Signing: CN can be included in code signing certificates to verify the identity of software publishers.

Formatting of the Common Name (CN):

The CN can take various forms depending on the type of entity:

• For Individuals: The CN may include the full name of the person.
• For Organizations: The CN may include the legal name of the organization.
• For Host Systems: The CN may include the fully qualified domain name (FQDN) of the host.

Importance of Accurate CN:

• Identity Verification: The CN must accurately reflect the true identity of the certificate holder for trust to be established.
• Hostname Verification: In SSL/TLS certificates, the CN must match the hostname of the server to prevent man-in-the-middle attacks.

Considerations for CN:

• Use of UTF-8: CN should be encoded in UTF-8 to support international characters if needed.
• Meaningful and Clear: The CN should be meaningful and clearly represent the entity to which the certificate belongs.
• Updates and Renewals: CN should be updated or renewed when there are changes to the entity's identity or attributes.

The Common Name (CN) is a crucial attribute within a digital certificate, enabling accurate identification and verification of entities in a PKI environment.