SecurityState Class

SecurityState Class

 

Provides a base class for requesting the security status of an action from the AppDomainManager object.

Namespace:   System.Security
Assembly:  mscorlib (in mscorlib.dll)


[SecurityCriticalAttribute]
[PermissionSetAttribute(SecurityAction::InheritanceDemand, Unrestricted = true)]
public ref class SecurityState abstract 

NameDescription
System_CAPS_protmethodSecurityState()

Initializes a new instance of the SecurityState class.

NameDescription
System_CAPS_pubmethodEnsureState()

When overridden in a derived class, ensures that the state that is represented by SecurityState is available on the host.

System_CAPS_pubmethodEquals(Object^)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethodFinalize()

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodIsStateAvailable()

Gets a value that indicates whether the state for this implementation of the SecurityState class is available on the current host.

System_CAPS_protmethodMemberwiseClone()

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

You must inherit from this class to provide a class that includes a property that specifies the security-sensitive action to be performed. The SecurityState object that is instantiated from the derived class is passed to the AppDomainManager::CheckSecuritySettings method to determine whether the host allows that action to be performed. The default implementation of the CheckSecuritySettings method always returns false. The method must be overridden to detect the actions that are allowed.

For example, if you want to access a Web camera in your library code, you would create a WebcamSecurityState object and call the EnsureState method to determine whether the host allows Web camera access, as shown in the following example. (You can find the code for WebcamSecurityState in the "Example" section.)

WebcamSecurityState securityState = new WebcamSecurityState("Safe access to Webcam", WebcamSecurityOptions.SafeAccess);
try
{
   securityState.EnsureState();
   // Allocate memory.
   }
catch (ApplicationException e)
{
    // Handle any exception that is thrown.
    System.Diagnostics.Debug.WriteLine(e.Message);
}

To process the call the AppDomainManager must be made aware of WebcamSecurityState through an override of the AppDomainManager::CheckSecuritySettings method, as shown in the following example.

[SecurityCritical]
public override bool CheckSecuritySettings(System.Security.SecurityState securityState)
{
   switch (securityState.ToString())
   {
      case "WebcamSecurityState":
      {
          if ((securityState as WebcamSecurityState).Options == WebcamSecurityOptions.SafeAccess)
              return PromptUser((securityState as WebcamSecurityState).Description);
           return false;
      }
   }
      return false;
}
private bool PromptUser(string text)
{
   // Replace the OpenFileDialog with a custom user prompt.
   OpenFileDialog o = new OpenFileDialog();
   o.Title = text;
   if (o.ShowDialog() == DialogResult.OK)
      return true;
   else
      return false;
}

The following example shows how to override the SecurityState class.

[SecurityCritical]
public enum WebcamSecurityOptions
    {
        SafeAccess,
        FullAccess
    }
[SecurityCritical]
public class WebcamSecurityState : SecurityState
{
    public WebcamSecurityState(string description, WebcamSecurityOptions options)
    {
        Options = options;
        Description = description;
    }
    public WebcamSecurityOptions Options { get; set; }
    public string Description { get; set; }
    public override void EnsureState()
    {
       if (!IsStateAvailable())
           throw new ApplicationException("WebcamSecurityState not available");
    }
 }

SecurityCriticalAttribute

requires full trust for the immediate caller. This class cannot be used by partially trusted or transparent code.

InheritanceDemand

for full trust for inheritors. This class cannot be inherited by partially trusted code.

.NET Framework
Available since 2.0
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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