What is an electronic document that binds a public key with an identity using a digital signature called?

A digital certificate is the correct term for an electronic document that binds a public key to an individual or organization's identity, secured by a digital signature. This certificate serves an essential role in public key infrastructure (PKI) by verifying that the entity in possession of the public key is indeed who they claim to be.

The digital signature in a certificate is generated using the private key of a trusted entity, usually a Certificate Authority (CA). This process ensures that a recipient can authenticate the source of the public key, thus fostering trust in digital communications and transactions. The certificate typically contains information such as the name of the issuing authority, the subject's public key, and other identifiers, all of which are critical for establishing secure connections.

In contrast, other terms like "token," "key exchange," and "identity proof" do not encapsulate this specific concept. A token generally refers to a physical or digital object used for authentication, a key exchange involves the methods and protocols used to securely share cryptographic keys, and identity proof might refer to various means of validating a person's identity but lacks the specific binding nature of public keys to identities that a certificate provides.