Input validation Input
Anything coming from external sources can be consider as input in a web application. Not only the user inserting data through a web form, but also data retrieved from a web service or database, headers sent from the browsers fall under this concept.
Defining what is known as trust boundary can help us to visualize all possible untrusted inputs. ASP.NET has different types of validations depending on the level of control to be applied. By default, web pages code is validated against malicious users. The following is a list types of validations used (MSDN, 2013):
A way of defining when input is safe can be done through defining a trust boundary.