F. Public Key Infrastructure ( PKI )
PKI is a system that manages encryption keys and identity
information for the human and mechanical components of a
network, which participate in secured communications[15].
For a person or a piece of equipment to enroll in a PKI, the
software on a user’s computer generates a pair of encryption
keys that will be used in secured communications: a public
and a private key. Alternatively, this can be generated by a
component of the operating system or functional software on a
network device.
The private key is never distributed or revealed; conversely,
the public key is freely distributed to any party that negotiates
a secure communication. During the enrollment process, the
user’s public key is sent in the certificate request to the
certification authority, which is responsible for the portion of
the organization to which that entity belongs. The user sends
his public key to the registration component of the
Certification Authorities (CA). Subsequently, the
administrator approves the request and the CA generates the
user’s certificate. After the user receives a certificate and
installs it on the computer, they can participate in the secured
network .
PKI is used most frequently for encrypted email
communications and IPsec tunnel negotiation, which both use
the identity and security features of the certificate. The
identity components determine the identity of the user, their
level of access to the particular type of communication under
negotiation, and the encryption information that protects the
communication from other parties who are not allowed access.
Communicating parties will exchange certificates, and inspect
the information presented by the other. The certificates are
checked to see if they are within their validity period, and if
the certificate was generated by a trusted PKI. If all the
identity information is appropriate, the public key is extracted
from the certificate and used to establish an encrypted session.