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RegistryKeyPermissionCheck Enumeration

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

Namespace:  Microsoft.Win32
Assembly:  mscorlib (in mscorlib.dll)

public enum RegistryKeyPermissionCheck

Member nameDescription
DefaultThe 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.
ReadSubTreeSecurity 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.
ReadWriteSubTreeSecurity 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.

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.

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.
 */

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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