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Do you believe this? GUIDGEN.EXE by Microsoft

  1. Jan 22, 2004 #1
    You must use Microsoft's GUIDGEN.EXE or (similar programs which use the same algorithm in it) to generate a unique GUID (Globally Unique Identifier) for each COM object and its interface/s you create.

    The program generates, so they say, a 128-bit vector which is guaranteed not to be replicated again on any machine at any time ever.

    Of course, you don't have to be online to use this program.

    Do you believe Microsoft's claim is true?
  2. jcsd
  3. Jan 22, 2004 #2


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    Well, 2^128 is a bit low, really it ought to be 2^256, but otherwise, yeah, it's plausible.

    It's called cryptographic hashing. You should be able to look it up for more info.

    With 2^128 bits, that's only 2^64 objects before colisions start being really likely, and it's actually concievable that there are 2^64 objects.
  4. Jan 23, 2004 #3
    probably an md5 algorithm.
  5. Jan 26, 2004 #4
    hmm. only about 34,028,236,692,093,846,346,337,460,743,177,000,000 possible combinations..... With a little bit of effort, it probably wouldn't be to hard to make somtthing that produces files with identical MD5 things.
  6. Jan 26, 2004 #5


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    The point of MD5 (and other hashes) is that it actually takes a huge amount of computational effort to generate two files with the same hash. Hashing would be useless if it was easy to do this.

    Also, I should note that computers already contain unique information. MAC address on LAN cards, for example, are unique. Each manufacturer is given a block of MACs, and they are never used twice. A gauranteed-unique serial number generator could easily be based on a machine's MAC address. (Though I don't know the actual implementation of Mickeysoft's program.)

    - Warren
  7. Aug 8, 2004 #6

    Your are correct that a random number would not be suficient to garantee the number was "globaly unique" however, Guid generation is not based entirly on random number generation, a GUID can be calculated a number of diffrent ways, but usually they are a combination of values such as the system time and the MAC address of your NIC these in themselfs are unique values assigned to your NIC by its manufacturer, each manufactuer having its own unique number and incramenting an aditional value for each card it produces.


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