Safest way to get processor ID or some hardware info

I need to get any info to identify a machine and what I was using so far was the following:

    internal static string GetProcessorId()
    {
        try
        {
            StringBuilder sb = new StringBuilder();
            using (System.Management.ManagementClass theClass = new System.Management.ManagementClass("Win32_Processor"))
            {
                using (System.Management.Managemen开发者_运维问答tObjectCollection theCollectionOfResults = theClass.GetInstances())
                {
                    foreach (System.Management.ManagementObject currentResult in theCollectionOfResults)
                    {
                        sb.Append(currentResult["ProcessorID"].ToString());
                    }
                }
            }
            return sb.ToString();
        }
        catch (Exception exception)
        {
            Console.WriteLine(exception.Message);
            return "";
        }
    }

But when I run this on Windows XP (from a Virtual Machine), my currentResult["ProcessorID"] is null. I'm not sure if it is because I'm using a virtual machine, but it might be because is XP. Anyway, I'm not very trustful of this code. Is it safe enough? Should I get a computer Id some other way? This is all part of a licensing system I'm developing.

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For a small tool I wrote (Windows Forms .NET 2.0), I needed something similar.

I wrote a helper class that simply uses some common information like HDD serial number through PInvoke of the GetVolumeInformation function.

This is by no way really safe or bullet-proof, but accurate enough to fit my needs.

(If you are interested this is the tool, if I'm allowed to link to)

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Even if it worked, it wouldn't do what you want. The ProcessorID gives you an identification of the process product (Pentium X with features Y and Z), not about the specific instance of the CPU. It is described thus:

Processor information that describes the processor features. For an x86 class CPU, the field format depends on the processor support of the CPUID instruction. If the instruction is supported, the property contains 2 (two) DWORD formatted values. The first is an offset of 08h-0Bh, which is the EAX value that a CPUID instruction returns with input EAX set to 1. The second is an offset of 0Ch-0Fh, which is the EDX value that the instruction returns. Only the first two bytes of the property are significant and contain the contents of the DX register at CPU reset—all others are set to 0 (zero), and the contents are in DWORD format.

The IBM PC hardware doesn't have any kind of fake-proof hardware identification.