11.2.2. Digital certificates

A digital certificate is a digital document conforming to the X.509 standard that certifies that a certain public key is owned by a particular user or organization. This document is signed by a third party (the CA). This data file contains the public key of its owner, as well as the following information:

  • Not before/Not after: Validity (from/to date) of the certificate.

  • Purpose: For what end may the certificate be used (for example, digital signature, data encryption, and so on).

  • Issuer: The Distinguished Name of the Certificate Authority that signed the certificate.

  • Subject: The Distinguished Name of the owner of the certificate.

  • Distinguished Name: The distinguished name (DN) usually contains the following information (not all the fields are mandatory, and other optional fields are also possible). A DN is often represented as a comma-separated list of fieldname-value pairs.

    • Country: 2-character country/region code.

    • State: State where the organization resides.

    • Locality: City where the organization resides.

    • Organization: Legal name of the organization.

    • Organizational Unit: Division of the organization.

    • Common Name: The common name is often the address of the website or the domain name of the organization, for example, www.example.com, or the name of the user in case of personal certificates.