Managing certificates

Overview

The Public Key Infrastructure (PKI) offers an infrastructure for securing network services through public key technologies and digital certificates, and for verifying the identities of the digital certificate owners.

A digital certificate is a binding of certificate owner identity information and a public key. Users can get certificates, use certificates, and revoke certificates. By leveraging digital certificates and relevant services like certificate and blacklist distribution, PKI supports authenticating the entities involved in communication, and therefore guarantees the confidentiality, integrity, and non-repudiation of data.

PKI terms

Digital certificate

A digital certificate is a file signed by a certificate authority (CA) that contains a public key and the related user identity information. A simplest digital certificate contains a public key, an entity name, and a digital signature from the CA. Generally, a digital certificate also includes the validity period of the key, the name of the CA and the sequence number of the certificate. A digital certificate must comply with the international standard of ITU-T_X.509. This document involves local certificate and CA certificate. A local certificate is a digital certificate signed by a CA for an entity. A CA certificate, also known as a "root certificate", is signed by the CA for itself.

CRL

An existing certificate might need to be revoked when, for example, the username changes, the private key leaks, or the user stops the business. Revoking a certificate will remove the binding of the public key with the user identity information. In PKI, the revocation is made through certificate revocation lists (CRLs). When a certificate is revoked, the CA publishes one or more CRLs to show all certificates that have been revoked. The CRLs contain the serial numbers of all revoked certificates and provide an effective way for checking the validity of certificates.

A CA might publish multiple CRLs when the number of revoked certificates is so large that publishing them in a single CRL might degrade network performance.

CA policy

A CA policy is a set of criteria that a CA follows in processing certificate requests, issuing and revoking certificates, and publishing CRLs. Usually, a CA advertises its policy in the form of certification practice statement (CPS). A CA policy can be acquired through out-of-band means such as phone, disk, and email. Because different CAs might use different methods to examine the binding of a public key with an entity, make sure you understand the CA policy before selecting a trusted CA for certificate request.

PKI architecture

A PKI system consists of entities, a CA, a registration authority (RA) and a PKI repository.

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