RegistryKeyPermissionCheck Enum

Definition

Namespace:

Microsoft.Win32

Assembly:

Microsoft.Win32.Registry.dll

Specifies whether security checks are performed when opening registry keys and accessing their name/value pairs.

public enum class RegistryKeyPermissionCheck

public enum RegistryKeyPermissionCheck

type RegistryKeyPermissionCheck = 

Public Enum RegistryKeyPermissionCheck

Inheritance

Object

ValueType

Enum

RegistryKeyPermissionCheck

Fields

Name	Value	Description
Default	0	The registry key inherits the mode of its parent. Security checks are performed when trying to access subkeys or values, unless the parent was opened with ReadSubTree or ReadWriteSubTree mode.
ReadSubTree	1	Security checks are not performed when accessing subkeys or values. A security check is performed when trying to open the current key, unless the parent was opened with ReadSubTree or ReadWriteSubTree.
ReadWriteSubTree	2	Security checks are not performed when accessing subkeys or values. A security check is performed when trying to open the current key, unless the parent was opened with ReadWriteSubTree.

Examples

The following code example creates a subkey containing 100 key/value pairs and closes it. The example opens the subkey with Default and records the time it takes to read all the values. Then the example opens the subkey with ReadSubTree and records the time it takes to read all the values. Finally, the example computes and displays the percentage improvement.

using System;
using Microsoft.Win32;
using System.Diagnostics;

public class Example
{
    public static void Main()
    {
        const int LIMIT = 100;
        RegistryKey cu = Registry.CurrentUser;
        const string testKey = "RegistryKeyPermissionCheckExample";

        Console.WriteLine("Generating {0} key/value pairs.", LIMIT);
        RegistryKey rk = cu.CreateSubKey(testKey);
        for (int i = 0; i < LIMIT; i++)
        {
            rk.SetValue("Key" + i, i);
        }

        rk.Close();

        Stopwatch s = new Stopwatch();

        // On the default setting, security is checked every time
        // a key/value pair is read.
        rk = cu.OpenSubKey(testKey, RegistryKeyPermissionCheck.Default);

        s.Start();
        for (int i = 0; i < LIMIT; i++)
        {
            rk.GetValue("Key" + i, i);
        }
        s.Stop();
        rk.Close();
        long delta1 = s.ElapsedTicks;

        s.Reset();

        // When the key is opened with ReadSubTree, security is
        // not checked when the values are read.
        rk = cu.OpenSubKey(testKey, RegistryKeyPermissionCheck.ReadSubTree);

        s.Start();
        for (int i = 0; i < LIMIT; i++)
        {
            rk.GetValue("Key" + i, i);
        }
        s.Stop();
        rk.Close();
        long delta2 = s.ElapsedTicks;

        double faster = (double) (delta1 - delta2) / (double) delta1;
        Console.WriteLine("ReadSubTree is {0}% faster for {1} values.",
            (faster * 100).ToString("0.0"), LIMIT);

        cu.DeleteSubKey(testKey);
    }
}

/* This code example produces output similar to the following:

Generating 100 key/value pairs.
ReadSubTree is 23.4% faster for 100 values.
 */

Imports Microsoft.Win32
Imports System.Diagnostics

Public Class Example
    
    Public Shared Sub Main() 

        Const LIMIT As Integer = 100
        Dim cu As RegistryKey = Registry.CurrentUser
        Const testKey As String = "RegistryKeyPermissionCheckExample"
        
        Console.WriteLine("Generating {0} key/value pairs.", LIMIT)
        Dim rk As RegistryKey = cu.CreateSubKey(testKey)

        For i As Integer = 0 To LIMIT
            rk.SetValue("Key" & i, i)
        Next i
        
        rk.Close()
        
        Dim s As New Stopwatch()
        
        ' On the default setting, security is checked every time
        ' a key/value pair is read.
        rk = cu.OpenSubKey(testKey, _
            RegistryKeyPermissionCheck.Default)
        
        s.Start()
        For i As Integer = 0 To LIMIT
            rk.GetValue("Key" & i, i)
        Next i
        s.Stop()
        rk.Close()
        Dim delta1 As Long = s.ElapsedTicks
        
        s.Reset()
        
        ' When the key is opened with ReadSubTree, security is 
        ' not checked when the values are read.
        rk = cu.OpenSubKey(testKey, _
            RegistryKeyPermissionCheck.ReadSubTree)
        
        s.Start()
        For i As Integer = 0 To LIMIT
            rk.GetValue("Key" & i, i)
        Next i
        s.Stop()
        rk.Close()
        Dim delta2 As Long = s.ElapsedTicks
        
        Dim faster As Double = _
            CDbl(delta1 - delta2) * 100.0 / CDbl(delta1)
        Console.WriteLine("ReadSubTree is {0}% faster for {1} values.", _
            faster.ToString("0.0"), LIMIT)
        
        cu.DeleteSubKey(testKey)
    
    End Sub 
End Class 

' This code example produces output similar to the following:
'
'Generating 100 key/value pairs.
'ReadSubTree is 23.4% faster for 100 values.
'

Remarks

When an application saves or retrieves a large number of registry settings from a set of subkeys, numerous redundant security checks are performed. This enumeration specifies when security checks on a key are to be omitted.

The following table shows when security checks are performed, based on the way the parent key and the current key are opened.

Parent key opened with	Current key opened with	Result
Default	Default	A security check is performed when accessing any value in the current key, or when attempting to access a subkey. This is the behavior in the .NET Framework versions 1.0 and 1.1.
Default	ReadSubTree	A security check is performed when trying to open the current key.
Default	ReadWriteSubTree	A security check is performed when trying to open the current key.
ReadSubTree	Default or ReadSubTree	No security checks are performed when opening the current key or its values.
ReadSubTree	ReadWriteSubTree	A security check is performed when trying to open the current key.
ReadWriteSubTree	Any	No security checks are performed when opening the current key or its values.