SecurityState Class

Definition

Namespace:

System.Security

Assembly:

System.Security.Permissions.dll

Source:

SecurityState.cs

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

public ref class SecurityState abstract

public abstract class SecurityState

type SecurityState = class

Public MustInherit Class SecurityState

Inheritance

Object

SecurityState

Derived

System.IO.IsolatedStorage.IsolatedStorageSecurityState

Examples

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");  
    }  
}    

Remarks

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.)

var 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;  
}   

Constructors

SecurityState()

Initializes a new instance of the SecurityState class.

Methods

EnsureState()	When overridden in a derived class, ensures that the state that is represented by SecurityState is available on the host.
Equals(Object)	Determines whether the specified object is equal to the current object. (Inherited from Object)
GetHashCode()	Serves as the default hash function. (Inherited from Object)
GetType()	Gets the Type of the current instance. (Inherited from Object)
IsStateAvailable()	Gets a value that indicates whether the state for this implementation of the SecurityState class is available on the current host.
MemberwiseClone()	Creates a shallow copy of the current Object. (Inherited from Object)
ToString()	Returns a string that represents the current object. (Inherited from Object)