Generating hardware based computerID

You can use the first MAC address, which is assigned by the manufacturer of the hardware and will never change.

Something like this:

/** 

  return string containing first MAC address on computer

 requires adding Iphlpapi.lib to project

*/
string GetMac()
{
    char data[4096];
    ZeroMemory( data, 4096 );
     unsigned long  len = 4000;
    PIP_ADAPTER_INFO pinfo = ( PIP_ADAPTER_INFO ) data;
    char sbuf[20];
    string sret;

    DWORD ret = GetAdaptersInfo( pinfo, &len );
    if( ret != ERROR_SUCCESS )
        return string("**ERROR**");

    for(int k = 0; k < 5; k++ ) {
        sprintf(sbuf,"%02X-",pinfo->Address[k]);
        sret += sbuf;
    }
    sprintf(sbuf,"%02X",pinfo->Address[5]);
    sret += sbuf;

    return( sret );
}

IMHO, this is sufficient for licensing software valued up to a thousand dollars, where all that is necessary is to prevent casual consumers from sharing your software with their neighbours. A motivated pirate can get around it, but pirates with sufficient knowledge and motivation are not frequent enough to make it worthwhile for you to spend any more effort trying to defeat them and, even more important, you do not want to inconvenience your honest clients.

If your software is so valuable that motivated pirates are a real threat, then the cost and inconvenience of a hardware dongle becomes justified.

Neither do I believe in piling on more hardware signatures, disk drive IDs, motherboard configurations and so on. The increase in security is minimal and the chance that something may go wrong increases greatly so that you will end up wasting hours supporting clients with unusual setups and pissing off unknown numbers who simply give up on you.

Implement a simple system with the MAC address, which always seems to work. Accept that an occasional pirate may get their kicks from breaking your licence. Focus your efforts on improving your software so that you will gain more honest clients.

A system may have more than one network card ( e.g. ethernet and wireless ) and it is possible for the user to change the presentation order ( why would a user do this? ). To handle this, a licence would need to match a network card present anywhere on the system, requiring code something like this:

/**

  The MAC addresses of ethernet network cards present on computer

  @param[out] vMAC vector of strings containing MAC addresses in XX-XX-XX-XX-XX-XX format

  returns empty vector on error

  See discussion of this 
  http://stackoverflow.com/questions/6131123/generating-hardware-based-computerid/6131231#6131231

*/

void cLicenser::GetMac( vector < string >& vMac )
{
    vMac.clear();
    char data[4096];
    ZeroMemory( data, 4096 );
    unsigned long  len = 4000;
    PIP_ADAPTER_INFO pinfo = ( PIP_ADAPTER_INFO ) data;

    DWORD ret = GetAdaptersInfo( pinfo, &len );
    if( ret != ERROR_SUCCESS )
        return;

    while ( pinfo )
    {
        // ignore software loopbacks
        if( pinfo->Type != MIB_IF_TYPE_LOOPBACK )
        {
            char sbuf[20];
            string sret;
            for(int k = 0; k < 5; k++ )
            {
                sprintf(sbuf,"%02X-",pinfo->Address[k]);
                sret += sbuf;
            }
            sprintf(sbuf,"%02X",pinfo->Address[5]);
            sret += sbuf;
            vMac.push_back( sret );
        }
        pinfo = pinfo->Next;
    }

}

I tried doing something similar a few years ago and failed. I tried using a combination of hardware ID's that I could read. Most CPU's have a CPUID, a unique number that is used to uniquely identify and track them. However the problem is that its not garunteed that each CPU out there will have this ID. In fact, when I tried it the Intel Celeron series did not have this ID. Certain Motherboards(mainly Intel) also shipped with a unique ID that you can use.

Here is a link to an article that describes how to get this information.

I also used any / all MAC ID's in combination with the CPU ID & MB ID as a seed to generate unique GUID. The more hardware ID's you use as seed the better this performed.The problem is that if you do upgrade any of the hardware components the ID changes and the software Key gets invalidated.

Also keep in mind that Virtual Machines complicate this even further. I think your best bet would be to do what Microsoft does.

Microsoft does use a similar approach where they take a Hardware fingerprint of a machine on which the OS is installed and communicate it along with the Registration Key to activate a copy of the OS / Office suite. If you upgrade your hardware significantly(I think 4 hardware components) the Key will change and you will have to contact Microsoft and provide proof to re-validate your copy of Windows.

If you only need to generate it once, the a GUID will be unique to the machine that created it. The problem is you'll get a different value every time you generate one. But if it's a one-off per machine, a GUID will work.

If it needs to be the same per machine and generated multiple times, the the MAC address is the universal ID for machines (though you may have multiple MACs to choose from).