Cisco IOS public key infrastructure (PKI) provides certificate management to support security protocols such as IP Security (IPSec), secure shell (SSH), and secure socket layer (SSL). This module identifies and describes concepts that are needed to understand, plan for, and implement a PKI.
A PKI is composed of the following entities: ...
- A distribution mechanism (such as Lightweight Directory Access Protocol [LDAP] or HTTP) for certificate revocation lists (CRLs)

Cross site scripting (also known as XSS) occurs when a web application gathers malicious data from a user. The data is usually gathered in the form of a hyperlink which contains malicious content within it. The user will most likely click on this link from another website, instant message, or simply just reading a web board or email message.
Usually the attacker will encode the malicious portion of the link to the site in HEX (or other encoding methods) so the request is less suspicious looking to the user when clicked on.
For example the code below is written in hex: <a
href=javascript:alert&#
x28'XSS')>Click Here</a>
is equivalent to:
<a href=javascript:alert('XSS')>Click Here</a>
Note: In the format "&#xhhhh", hhhh is the code point in hexadecimal form.