Which of the following best describes a digital certificate?

A digital certificate serves as a critical component of public key infrastructure (PKI) by binding a public key to an individual's or entity's identity. This means that it associates cryptographic keys with the actual identity of the certificate holder, which can be an individual, organization, or device. The digital certificate includes the public key, information about the identity it represents, and is typically signed by a trusted Certificate Authority (CA). This signature verifies the authenticity of the certificate, thereby establishing trust in the public key it encompasses.

The relevance of the correct answer lies in its ability to facilitate secure communications and transactions online. By providing a reliable way to verify identities, digital certificates help prevent impersonation and ensure that parties involved in electronic transactions can trust one another.

In contrast, the other options do not accurately encapsulate the purpose or function of a digital certificate. A legal document certifying permission to operate pertains more to regulatory and compliance issues rather than cryptographic identity binding. A coded message used for encryption describes the nature of encrypted data rather than the identity verification function of a certificate. Lastly, a security policy document for network management relates to governance and operational protocols rather than the cryptographic integrity and identity validation that a digital certificate provides.