C# code to change the default program attached with an extension using a custom progid with hash in windows 8

问题

Purpose: Associate a new progid to an extension so that file will open with new associated program.

Programming Language: C#

Description:

I want to create a program to associate another program with an extension from my recommended program list. My program is working in windows-xp and windows-7 but it is not working in windows-8. when i searched for the issue, i found that in Windows-8 there is an additional key called "Hash".

I am not able to find the hash for my new progid.

Steps Being Followed:

Created a class say "MyTest.txt" in HKEY_CLASSES_ROOT eg: HKEY_CLASSES_ROOT MyTest.txt Shell Open Command (Default) "[PATH TO NOTEPAD] "%1""

I noticed that same key is also created in LOCAL_MACHINE folder

Now I want to assign this "MyTest.txt" ProgID to

[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts.txt\UserChoice]

"Hash"="????"

"ProgId"="MyTest.txt"

But I am unable to find the Hash for my newly created ProgId "MyTest.txt" in C#.

Code Using C#:

public void changeExtensionDefaultProgram(string fileext,string operationmode, string oldkeyname, string fileopenerpath)
{                
    try
    {
        if (!string.IsNullOrEmpty(fileext))
        {
            //Global declaration for new custom key
            string sCustomkeyName = string.Format("MYTest.{0}", fileext);

            RegistryKey OurKey = Registry.LocalMachine;
            RegistryKey ParentKey = Registry.LocalMachine;
            RegistryKey GlobalLocalMachineKey = Registry.LocalMachine;
            RegistryKey GlobalRootKey = Registry.ClassesRoot;

            string keyToCopy = @"SOFTWARE\Classes";
            ParentKey = ParentKey.OpenSubKey(keyToCopy, true);

            string programopencommand = string.Format(@"SOFTWARE\Classes\{0}\Shell\{1}\Command", oldkeyname, operationmode);
            OurKey = OurKey.OpenSubKey(programopencommand, true);
            if (OurKey != null)
            {
                    //check if backup exists then do not take backup, along with source key
                    string backupkeyName = string.Format("MyBKP{0}", fileext);
                    RegistryKey rBackupKeyName = GlobalRootKey.OpenSubKey(backupkeyName, true);
                    if (rBackupKeyName==null)
                    {
                        //backup the keys with a new name MyBKP{ext}
                        FileAssoc.CopyKey(GlobalRootKey, oldkeyname, backupkeyName);
                        MessageBox.Show(string.Format("Backup Done -- GlobalRootKey=> oldkeyname:{0} as newbackupname:{1}", oldkeyname, backupkeyName));
                    }
                    //check if MyTest.{ext} Custom Class for extension exists
                    RegistryKey rCustomkeyName = GlobalRootKey.OpenSubKey(sCustomkeyName, true);
                    if (rCustomkeyName == null)
                    {
                        //copy the keys with a new name MyTest.{ext}
                        FileAssoc.CopyKey(GlobalRootKey, oldkeyname, sCustomkeyName);
                    }
                    if (rBackupKeyName != null)
                    {
                        rBackupKeyName.Close();
                    }

                    if (rCustomkeyName != null)
                    {
                        rCustomkeyName.Close();
                    }

                //Perform in localmachine 
                bool isFlagSet = setMicrosoftDefaultProgID(fileext, sCustomkeyName, fileopenerpath);
                if (isFlagSet)
                {
                    string newopencommand = string.Format(@"SOFTWARE\Classes\{0}\Shell\{1}\Command", sCustomkeyName, operationmode);
                    rCustomkeyName = GlobalLocalMachineKey.OpenSubKey(newopencommand, true);
                    if (rCustomkeyName != null)
                    {
                        rCustomkeyName.SetValue("", "\"" + fileopenerpath + "\"" + " \"%1\"");
                        MessageBox.Show(string.Format("going to set GlobalRootKey\\{0} with fileopenerpath:{1}", programopencommand, fileopenerpath));
                        rCustomkeyName.Close();
                    }
                    else
                    {
                        MessageBox.Show(string.Format("Failed to modify GlobalRootKey\\{0} with fileopenerpath:{1}", programopencommand, fileopenerpath));
                    }
                }
            }
        };
    }
    catch (Exception ex)
    {
        MessageBox.Show("changeExtensionDefaultProgram()::Exception raised" + ex.ToString());
    }
}

public bool setMicrosoftDefaultProgID(string fileextension, string keyname, string fileopenerpath)
{
    try
    {

        RegistryKey OurKey = Registry.CurrentUser;

        //HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.txt\UserChoice = MyTest.txt
        string programopencommand = string.Format(@"Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\{0}\UserChoice", fileextension);
        try
        {
            cSecurityOwnerShip sec = new cSecurityOwnerShip();
            string name = sec.UserName(cSecurity.EXTENDED_NAME_FORMAT.NameSamCompatible);

            if (name == null)
            {
                name = sec.UserName();
            }
            string sKey = OurKey.ToString()+@"\" + programopencommand;
            try
            {
                sec.ChangeMYKeyOwnership(sKey, cSecurityOwnerShip.SE_OBJECT_TYPE.SE_REGISTRY_KEY);
            }
            catch (Exception ex)
            {
                sec.ChangeMyKeyPermissions(cSecurityOwnerShip.ROOT_KEY.HKEY_CURRENT_USER, programopencommand, name, cSecurityOwnerShip.eRegAccess.Full_Control, cSecurityOwnerShip.eAccsType.Access_Allowed, cSecurityOwnerShip.eFlags.Inherit_Child);
            }

            RegistryKey NewSubKey = OurKey.CreateSubKey(programopencommand);
            if (NewSubKey != null)
            {
                try
                {
                    if (NewSubKey != null)
                    {

                        NewSubKey.SetValue("ProgID", keyname);
                        //NewSubKey.SetValue("Hash", "v8gh4ng+Pro=");
                        return true;
                    }
                    else
                        return false;
                }
                catch (Exception ex)
                {

                    MessageBox.Show("setMicrosoftDefaultProgID()::SetValue() Exception raised" + ex.ToString());
                    return false;
                }
            }
            else
            {
                MessageBox.Show(string.Format("setMicrosoftDefaultProgID()::programopencommand:{0} not exist", programopencommand));
                return false;
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(string.Format("setMicrosoftDefaultProgID()::Exception raised :{0}", ex.ToString()));
            return false;
        }

    }
    catch (Exception ex)
    {
        MessageBox.Show("setMicrosoftDefaultProgID()::Exception raised" + ex.ToString());
        return false;
    }
    finally
    {

    }
}

Issue i am facing is in this commented line to find and change "Hash"

//NewSubKey.SetValue("Hash", "v8gh4ng+Pro=");

回答1:

Windows 8 does not want random apps tampering with default application associations. Users and only users get to decide what application they choose for a file extension.

Don't do this. Let the user choose default application by opening "Default Programs" dialog from Control Panel.

If you're in a corporate environment and want to copy settings, you can export associations using group policies. See Windows 8: Associate a file Type or protocol with a specific app using GPO.

来源：https://stackoverflow.com/questions/26031054/c-sharp-code-to-change-the-default-program-attached-with-an-extension-using-a-cu