H3C Technologies H3C S5120 Series Switches - Manual (Page 449)

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CA
A CA is a trusted authority responsible for issuing and managing digital certificates. A CA issues
certificates, specifies the validity periods of certificates, and revokes certificates as needed by
publishing CRLs.
RA
A registration authority (RA) is an extended part of a CA or an independent authority. An RA can
implement functions including identity authentication, CRL management, key pair generation and key
pair backup. The PKI standard recommends that an independent RA be used for registration
management to achieve higher security of application systems.
PKI repository
A PKI repository can be a Lightweight Directory Access Protocol (LDAP) server or a common database.
It stores and manages information like certificate requests, certificates, keys, CRLs and logs while
providing a simple query function.
LDAP is a protocol for accessing and managing PKI information. An LDAP server stores user
information and digital certificates from the RA server and provides directory navigation service. From
an LDAP server, an entity can retrieve local and CA certificates of its own as well as certificates of other
entities.
Applications of PKI
The PKI technology can satisfy the security requirements of online transactions. As an infrastructure,
PKI has a wide range of applications. Here are some application examples.
VPN
A virtual private network (VPN) is a private data communication network built on the public
communication infrastructure. A VPN can leverage network layer security protocols (for instance, IPsec)
in conjunction with PKI-based encryption and digital signature technologies for confidentiality.
Secure e-mail
E-mails require confidentiality, integrity, authentication, and non-repudiation. PKI can address these
needs. The secure e-mail protocol that is currently developing rapidly is Secure/Multipurpose Internet
Mail Extensions (S/MIME), which is based on PKI and allows for transfer of encrypted mails with
signature.
Web security
For web security, two peers can establish an SSL connection first for transparent and secure
communications at the application layer. With PKI, SSL enables encrypted communications between a
browser and a server. Both the communication parties can verify the identity of each other through
digital certificates.
Operation of PKI
In a PKI-enabled network, an entity can request a local certificate from the CA and the device can check
the validity of certificates. Here is how it works:
1) An entity submits a certificate request to the RA.