using three methods the sequerity is provided

1) Authorazation/Authentication
       Allowing valid user and preventing invalid users.....

2) Access Control
      Permission to valid user to access user 
fctionalitites in software build.

3) Encryption/Dis\cryption
         Data conversions in b/n client process and server 
provcess to prevent third party avccessing

Security testing means whether our web application is 
vulnerable for hackers.
1.X-SS Cross Site Scripting
2.URL Injection

to provide the security to webapplictions by giving some
algorithms and security certificates, i can give one example.

suppose dotnet application provides itself security to its
applications, like sha algorithm,or we can purchase security
certificates,
testing point of view we can check weather the data is
encrypting or not and one more we should check the URL paths
whether the url is showing our usernames and passwords

thanks
chandu

There is different type of methods are using for security
testing
1)Authorization and Authentication:For checking the valid
and invalid user.
2)Access Control:access permission to valid user to access
user functionalities in application.
3)Encryption and Decryption: Data conversions in between
client process and server process to prevent third party
accessing

The above techniques using for security testing for web
application.