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ESR to Shred SCO Claims?

webmaven writes "According to this article in eWEEK, ESR has released a utility called comparator for analyzing the similarity of source code trees. The technical details are interesting, in that ESR says he is using an implementation of a refined version of the 'shred' algorithm, with higher performance (on machines with enough RAM) than other versions. ESR won't say whether he intends the comparator to be used to compare older Unix code to Linux so as to be able to refute SCO's claims, but it's obviously well suited for such a purpose. Interestingly, as the shred algorithm can run reports on source trees using only the MD5 signature shreds (once generated), it is possible to use it to compare trees without direct access to the source code itself, leading to a possible use in comparing various proprietary source trees with each other and with Freely available code bases such as Linux and *BSD without requiring actual disclosure of the proprietary source code (a neutral third party could generate the shreds on a company's premises, and leave without taking a copy of the source with them). I'll be interested to see if (or which of) the proprietary vendors allow their source trees to be 'shredded' for such comparisons, and whether this becomes a standard forensic technique in source-code copyright and trade-secret disputes."

9 of 554 comments (clear)

  1. Re:maybe... by jmv · · Score: 5, Interesting

    Actually, combine this with the "shared source" program from MS and it would be easy to see if MS did (or did not) copy GPL code into Windows as some suggest.

  2. Other uses? by Not_Wiggins · · Score: 4, Interesting

    It might be interesting to see how different families of Linux/Unix compare... maybe generate a veritable "family tree" of relationships.

    Of course, that also depends more on how differences are actually calculated. Still, could make an interesting project to relate OSes based on how much shared code they still retain and show it in a graphical tree format, ala "family tree." 8)

    --
    Diplomacy is the art of saying, "Nice doggie!" until you can find a rock.
  3. Re:Can Someone Explain? by stratjakt · · Score: 4, Interesting

    Perhaps if you parsed them both, and compared the resulting object code, right before compilation?

    That way if your variable is called numOfPorts and mine is called countOfPorts, the parsed code is the same for both, when stuff like that becomes meaningless.

    Even if not, SCO seems to be saying that much of the code is copy-n-paste anyways.

    --
    I don't need no instructions to know how to rock!!!!
  4. Be careful... by nolife · · Score: 4, Interesting

    The more points you discover and disprove now with SCO's claims.. the higher quality, more refined, and detailed SCO's evidence will be when this setup finally gets to a court in front of a judge. If they went to court two months ago or even today, they would have been sent home quickly with bascially easy to disprove evidence. With the help of the open source community, they are slowly changing their weapon of choice from a shotgun to a rifle.

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  5. IBM has a project called History Flow by TedTschopp · · Score: 5, Interesting

    This is perhaps a better project and it would be interesting to see this tool run against the source.

    History Flow The following is from their website:

    history flow
    visualizing dynamic, evolving documents and the interactions of multiple collaborating authors:

    Motivation
    Most documents are the product of continual evolution. An essay may undergo dozens of revisions; source code for a computer program may undergo thousands. And as online collaboration becomes increasingly common, we see more and more ever-evolving group-authored texts. This site is a preliminary report on a simple visual technique, history flow, that provides a clear view of complex records of contributions and collaboration.

    --
    Fantasy remains a human right; we make in our measure and in our derivative mode... -- JRR Tolkien
  6. Who says SCO gets to court first? by JoeBuck · · Score: 4, Interesting

    If we can show that SCO's violating the BSD license, maybe we can convince some BSD copyright holder to sue them first, and demand as part of discovery the MD5 checksums from "shred", showing duplicated BSD code but no duplicated BSD copyright.

  7. Re:Slim to None by JoeBuck · · Score: 4, Interesting

    But IBM already has a copy of SCO's code; they licensed it after all. They can release the output of "shred" without violating their agreements with SCO.

  8. derivative work? by donutz · · Score: 4, Interesting

    Presumably any of the many people with legal rights to SCO source code can publish the hash list without divulging any of SCO's (ahem) "IP".

    Would these hashes of SCO source code be considered derivative works? That could have copyright implications...

  9. Re:MD5 easily fooled by dmiller · · Score: 4, Interesting

    So, you've downloaded Comparator, and run tests, then.

    I didn't need to, the following is in the readme:

    comparator does not attempt to do semantic analysis and catch relatively trivial changes like renaming of variables, etc. This is because comparator is designed not as a tool to detect plagiarism of ideas (the subject of patent law), but as a tool to detect copying of the expression of ideas (the subject of copyright law).

    He's wrong BTW (and he is smart enough to know it, which makes this a deliberate deception). A work is no less subject to copyright if someone does a global search and replace on a variable name.