Is there really any way to uniquely identify any computer at all

Question

I know there are a number of similar questions in stackoverflow such as the followings:

• What's a good way to uniquely identify a computer?
• What is a good unique PC identifier?
• Unique computer id C#
• WIN32_Processor::Is ProcessorId Unique for all computers
• How to uniquely identify computer using C#?

... and dozens more and I have studied them all.

The problem is that some of the accepted answers have suggested MAC address as an unique identifier which is entirely incorrect. Some other answers have suggested to use a combination of various components which seems more logical. However, in case of using a combination it should be considered which component is naturally unlikely to be changed frequently. A few days ago we developed a key generator for a software licensing issue where we used the combination of CPUID and MAC to identify a windows pc uniquely and till practical testing we thought our approach was good enough. Ironically when we went testing it we found three computers returning the same id with our key generator!

So, is there really any way to uniquely identify any computer at all? Right now we just need to make our key generator to work on windows pc. Some way (if possible at all) using c# would be great as our system is developed on .net.

Update:

Sorry for creating some confusions and an apparently false alarm. We found out some incorrectness in our method of retrieving HW info. Primarily I thought of deleting this question as now my own confusion has gone and I do believe that a combination of two or more components is good enough to identify a computer. However, then I decided to keep it because I think I should clarify what was causing the problem as the same thing might hurt some other guy in future.

This is what we were doing (excluding other codes):

We were using a getManagementInfo function to retrieve MAC and Processor ID

private String getManagementInfo(String StrKey_String, String strIndex)
    {
        String strHwInfo = null;
        try
        {
            ManagementObjectSearcher searcher = new ManagementObjectSearcher("select * from " + StrKey_String);
            foreach (ManagementObject share in searcher.Get())
            {
                strHwInfo += share[strIndex];
            }
        }
        catch (Exception ex)
        {
            // show some error message
        }
        return strHwInfo;
    } 

Then where needed we used that function to retrieve MAC Address

string strMAC = getManagementInfo("Win32_NetworkAdapterConfiguration", "MacAddress");

and to retrieve ProcessorID

string strProcessorId = getManagementInfo("Win32_Processor", "ProcessorId");

At this point, strMAC would contain more than one MAC address if there are more than one. To take only one we just took the first 17 characters (12 MAC digits and 5 colons in between).

strMAC = strMAC.Length > 17 ? strMAC.Remove(17) : strMAC;

This is where we made the mistake. Because getManagementInfo("Win32_NetworkAdapterConfiguration", "MacAddress") was returning a number of extra MAC addresses that were really in use. For example, when we searched for MAC addresses in the command prompt by getmac command then it showed one or two MAC addresses for each pc which were all different. But getManagementInfo("Win32_NetworkAdapterConfiguration", "MacAddress") returned four to five MAC addresses some of which were identical for all computers. As we just took the first MAC address that our function returned instead of checking anything else, the identical MAC addresses were taken in strMAC incidently.

The following code by Sowkot Osman does the trick by returning only the first active/ enabled MAC address:

private static string macId()
    {
        return identifier("Win32_NetworkAdapterConfiguration", "MACAddress", "IPEnabled");
    }

private static string identifier(string wmiClass, string wmiProperty, string wmiMustBeTrue)
    {
        string result = "";
        System.Management.ManagementClass mc = new System.Management.ManagementClass(wmiClass);
        System.Management.ManagementObjectCollection moc = mc.GetInstances();
        foreach (System.Management.ManagementObject mo in moc)
        {
            if (mo[wmiMustBeTrue].ToString() == "True")
            {
                //Only get the first one
                if (result == "")
                {
                    try
                    {
                        result = mo[wmiProperty].ToString();
                        break;
                    }
                    catch
                    {
                    }
                }
            }
        }
        return result;
    }
    //Return a hardware identifier
    private static string identifier(string wmiClass, string wmiProperty)
    {
        string result = "";
        System.Management.ManagementClass mc = new System.Management.ManagementClass(wmiClass);
        System.Management.ManagementObjectCollection moc = mc.GetInstances();
        foreach (System.Management.ManagementObject mo in moc)
        {
            //Only get the first one
            if (result == "")
            {
                try
                {
                    result = mo[wmiProperty].ToString();
                    break;
                }
                catch
                {
                }
            }
        }
        return result;
    }

However, I was absolutely right about the identical Processor ID issue. All three returned the same Processor ID when we put wmic cpu get ProcessorId command in their command prompts.

Now we have decided to use Motherboard serial number instead of Processor ID to make a combination with MAC address. I think our purpose will be served with this way and if it doesn't in some cases then we should let it go in those few cases.

Answer 1

How about adding motherboard serial number as well e.g.:

using System.management;


//Code for retrieving motherboard's serial number
ManagementObjectSearcher MOS = new ManagementObjectSearcher("Select * From Win32_BaseBoard");
foreach (ManagementObject getserial in MOS.Get())
{
textBox1.Text = getserial["SerialNumber"].ToString();
}

//Code for retrieving Processor's Identity
MOS = new ManagementObjectSearcher("Select * From Win32_processor");
foreach (ManagementObject getPID in MOS.Get())
{
textBox2.Text = getPID["ProcessorID"].ToString();
}

//Code for retrieving Network Adapter Configuration
MOS = new ManagementObjectSearcher("Select * From Win32_NetworkAdapterConfiguration");
foreach (ManagementObject mac in MOS.Get())
{
textBox3.Text = mac["MACAddress"].ToString();
}

Answer 2

The fact in getting a globally unique ID is, only MAC address is the ID that will not change if you set up your system all over. IF you are generating a key for a specific product, the best way to do it is assigning unique IDs for products and combining the product ID with MAC address. Hope it helps.

Answer 3

I Completely agree with just the above comment.

For Software licensening, you can use:

Computer MAC Address (Take all if multiple NIC Card) + Your software Product Code

Most of the renowned telecom vendor is using this technique.

Answer 4

However, I was absolutely right about the identical Processor ID issue. All three returned the same Processor ID when we put wmic cpu get ProcessorId command in their command prompts.

Processor ID will be same if all the systems are running as virtual machines on the same hypervisor.

MAC ID seems fine. Only thing is users must be provided the option to reset the application, in case the MAC changes.

Answer 5

It looks like custom kitchen is the way for that.

SMBIOS UUID (motherboard serial) is not robust, but works fine in 99% cases. However some brands will set the same UUID for multiple computers (same production batch maybe). Getting it requires WMI access for the user (if he's not administrator), you can solve that by starting an external process asking administrator priviledges (check codeproject.com/Articles/15848/WMI-Namespace-Security)

Windows Product ID might be good, but I read it could be identical in some circumstances (https://www.nextofwindows.com/the-best-way-to-uniquely-identify-a-windows-machine) Could someone clarify if the same Product ID (not product key) might be present on multiple computers ?

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\MachineGuid seems interesting. It's generated when installing Windows and if changed, it requires to reactivate Windows.

Mac Addresses are interresting but you can only take the first one or your unique ID will change when the interface is disabled, or when another network interface is added and appears first etc.

Hard Drive serial number is nice but when installing a ghost, it might also override the serial number from the original drive... And the HD serial is very easy to change.

The best might be to generate an ID with a combination of those machine identifiers and decide if the machine is the same by comparing those identifiers (ie if at least one Mac address + either SMBIOS UUID or Product ID is ok, accept)