Reputation: 15720

Generating a unique machine id

I need to write a function that generates an id that is unique for a given machine running a Windows OS.

Currently, I'm using WMI to query various hardware parameters and concatenate them together and hash them to derive the unique id. My question is, what are the suggested parameters I should use? Currently, I'm using a combination of bios\cpu\disk data to generate the unique id. And am using the first result if multiple results are there for each metric.

However, I ran into an issue where a machine that dual boots into 2 different Windows OS generates different site codes on each OS, which should ideally not happen.

For reference, these are the metrics I'm currently using:

Win32_Processor:UniqueID,ProcessorID,Name,Manufacturer,MaxClockSpeed
Win32_BIOS:Manufacturer
Win32_BIOS:SMBIOSBIOSVersion,IdentificationCode,SerialNumber,ReleaseDate,Version
Win32_DiskDrive:Model, Manufacturer, Signature, TotalHeads
Win32_BaseBoard:Model, Manufacturer, Name, SerialNumber
Win32_VideoController:DriverVersion, Name

Upvotes: 114

Answers (13)

IInspectable

Reputation: 51479

Starting with Windows 10 1607 ("Anniversary Update" Build 14393), the system can generate a unique device ID via the Windows.System.Profile.SystemIdentification class. GetSystemIdForPublisher() returns a device ID, that

Persists across restarts, reinstalls and upgrades of Windows, including clean installs

This API uses the TPM or UEFI. If neither is present, the system generates a new ID and persists it in the registry. In that case, the above guarantees do not hold. The API will report how reliable the ID is through the Source property.

The following C++ code requests the device ID and prints a hex-encoded representation to STDOUT alongside its source:

#include <winrt/Windows.System.Profile.h>
#include <winrt/Windows.Security.Cryptography.h>

#include <iostream>

namespace wsp = ::winrt::Windows::System::Profile;
namespace wsc = ::winrt::Windows::Security::Cryptography;

int main()
{
    auto buffer = wsp::SystemIdentification::GetSystemIdForPublisher();

    auto const id = buffer.Id();
    auto const hex_id = wsc::CryptographicBuffer::EncodeToHexString(id);

    ::std::wcout << L"Id: " << hex_id.c_str() << ::std::endl;

    wchar_t const* src = nullptr;
    switch (buffer.Source())
    {
    case wsp::SystemIdentificationSource::Tpm:
        src = L"TPM";
        break;
    case wsp::SystemIdentificationSource::Uefi:
        src = L"UEFI";
        break;
    case wsp::SystemIdentificationSource::Registry:
        src = L"Registry";
        break;
    case wsp::SystemIdentificationSource::None:
        src = L"None";
        break;
    default:
        src = L"<unknown>";
        break;
    }

    ::std::wcout << L"Source: " << src << ::std::endl;
}

This standard "Windows Console Application (C++/WinRT)" has the following packages.config file:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="Microsoft.Windows.CppWinRT" version="2.0.230706.1" targetFramework="native" />
</packages>

Raymond Chen's blog post How can I get a signature for a Windows system that will remain unchanged even if the user reinstalls Windows? has a few more details that aren't spelled out in the documentation.

Upvotes: 1

StanBarr

Reputation: 5

I had an additional constraint, I was using .net express so I couldn't use the standard hardware query mechanism. So I decided to use power shell to do the query. The full code looks like this:

Private Function GetUUID() As String
    Dim GetDiskUUID As String = "get-wmiobject Win32_ComputerSystemProduct  | Select-Object -ExpandProperty UUID"
    Dim X As String = ""
    Dim oProcess As New Process()
    Dim oStartInfo As New ProcessStartInfo("powershell.exe", GetDiskUUID)
    oStartInfo.UseShellExecute = False
    oStartInfo.RedirectStandardInput = True
    oStartInfo.RedirectStandardOutput = True
    oStartInfo.CreateNoWindow = True
    oProcess.StartInfo = oStartInfo
    oProcess.Start()
    oProcess.WaitForExit()
    X = oProcess.StandardOutput.ReadToEnd
    Return X.Trim()
End Function

Upvotes: 0

Jonas Engström

Reputation: 5065

Parse the SMBIOS yourself and hash it to an arbitrary length. See the PDF specification for all SMBIOS structures available.

To query the SMBIOS info from Windows you could use EnumSystemFirmwareEntries, EnumSystemFirmwareTables and GetSystemFirmwareTable.

IIRC, the "unique id" from the CPUID instruction is deprecated from P3 and newer.

Upvotes: 27

Paul Alexander

Reputation: 32377

With our licensing tool we consider the following components

MAC Address
CPU (Not the serial number, but the actual CPU profile like stepping and model)
System Drive Serial Number (Not Volume Label)
Memory
CD-ROM model & vendor
Video Card model & vendor
IDE Controller
SCSI Controller

However, rather than just hashing the components and creating a pass/fail system, we create a comparable fingerprint that can be used to determine how different two machine profiles are. If the difference rating is above a specified tolerance then ask the user to activate again.

We've found over the last 8 years in use with hundreds of thousands of end-user installs that this combination works well to provide a reliably unique machine id - even for virtual machines and cloned OS installs.

Upvotes: 40

Fabio Ceconello

Reputation: 16049

I had the same problem and after a little research I decided the best would be to read MachineGuid in registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography, as @Agnus suggested. It is generated during OS installation and won't change unless you make another fresh OS install. Depending on the OS version it may contain the network adapter MAC address embedded (plus some other numbers, including random), or a pseudorandom number, the later for newer OS versions (after XP SP2, I believe, but not sure). If it's a pseudorandom theoretically it can be forged - if two machines have the same initial state, including real time clock. In practice, this will be rare, but be aware if you expect it to be a base for security that can be attacked by hardcore hackers.

Of course a registry entry can also be easily changed by anyone to forge a machine GUID, but what I found is that this would disrupt normal operation of so many components of Windows that in most cases no regular user would do it (again, watch out for hardcore hackers).

Upvotes: 85

AngelBlaZe

Reputation: 464

In my program I first check for Terminal Server and use the WTSClientHardwareId. Else the MAC address of the local PC should be adequate.

If you really want to use the list of properties you provided leave out things like Name and DriverVersion, Clockspeed, etc. since it's possibly OS dependent. Try outputting the same info on both operating systems and leave out that which differs between.

Upvotes: 1

cmcginty

Reputation: 235

For one of my applications, I either use the computer name if it is non-domain computer, or the domain machine account SID for domain computers. Mark Russinovich talks about it in this blog post, Machine SID:

The final case where SID duplication would be an issue is if a distributed application used machine SIDs to uniquely identify computers. No Microsoft software does so and using the machine SID in that way doesn’t work just for the fact that all DC’s have the same machine SID. Software that relies on unique computer identities either uses computer names or computer Domain SIDs (the SID of the computer accounts in the Domain).

You can access the domain machine account SID via LDAP or System.DirectoryServices.

Upvotes: 1

gizmo

Reputation: 11909

What about just using the UniqueID of the processor?

Upvotes: 3

BCS

Reputation: 78625

Look up CPUID for one option. There might be some issues with multi-CPU systems.

Upvotes: -1

Kyle Cronin

Reputation: 79123

You should look into using the MAC address on the network card (if it exists). Those are usually unique but can be fabricated. I've used software that generates its license file based on your network adapter MAC address, so it's considered a fairly reliable way to distinguish between computers.

Upvotes: 1

Christopher Cashell

Reputation: 800

Can you pull some kind of manufacturer serial number or service tag?

Our shop is a Dell shop, so we use the service tag which is unique to each machine to identify them. I know it can be queried from the BIOS, at least in Linux, but I don't know offhand how to do it in Windows.

Upvotes: 0

Jonathan Adelson

Reputation: 3321

I hate to be the guy who says, "you're just doing it wrong" (I always hate that guy ;) but...

Does it have to be repeatably generated for the unique machine? Could you just assign the identifier or do a public/private key? Maybe if you could generate and store the value, you could access it from both OS installs on the same disk?

You've probably explored these options and they doesn't work for you, but if not, it's something to consider.

If it's not a matter of user trust, you could just use MAC addresses.

Upvotes: 0

bfabry

Reputation: 1904

Maybe cheating a little, but the MAC Address of a machines Ethernet adapter rarely changes without the motherboard changing these days.

Upvotes: 0

Generating a unique machine id

Answers (13)

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