The code access security mechanism in the .NET Framework performs these functions:

• Defines permissions representing the right to access various system resources.
• Enables the configuration of security policy for code groups (groups of applications).
• Enables code to request required and useful permissions, and specifies the permissions the code shouldn't have.
• Ensures permissions are granted to each assembly loaded, based on the permissions requested by the code and the operations permitted by security policy.
• Enables code to ensure its host clients have specific permissions or that clients possess a digital signature, identifying a specific site or organization and restricting access to their client applications.
• Restricts code at run time by comparing the granted permissions of every caller on the stack to the permissions required to access the appropriate resources.