Slashdot Mirror
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."
microsoft can just shred their source tree and start anew. maybe...
My problem? I was perfectly gruntled, until some numbnuts came by and dissed me.
Of course, we can just trust SCO to show the right hashes. Why would they lie?
Wer mit Ungeheuern kämpft, mag zusehn, dass er nicht dabei zum Ungeheuer wird. --Nietzsche
If there is, why couldn't MD5 shreds be used as a lossy compression scheme for code?
Go here to create your own Slashdot dis
This will only serve as another black eye on the Open Source community. ESR should know better that to shred SCO material prior to a trial.
Did he write it in Python? And did he complete it in under 6 hours?
I think the question here is not about whether there is common code between SCO and Linux. There is no doubt that there will be common code because of the common origins. The issue here is that SCO does not own that code.
This shouldn't be relied upon in the court of law. Although I acknowledge that SCO likely has no IP claim over Linux, it should have a fair case. A program that would rule out code similarities does not rule out code that is based on the SCO code. There are hundreds of ways to do a single thing, and if the GNU/Linux took ideas from the SCO kernel, SCO may be as eligible for compensation as if it were directly copied from SCO.
And why did you staple the trout to the RAM?
The truth is out there, we will finally get to it without signing a SCO NDA. This should end the case before it begins. SHRED ON!
"Curiosity killed the cat, but for a while I was a suspect."- Steven Wright
This just in. SCO to sue ESR for patent infringement over "comparator", a software package that performs comparison between different sets of source code to determine if any code is copied between them.
Fun with Anagarams! LADS HOST, SHALT DOS. HAS DOLTS. AD SLOTHS, HATS SOLD. ASS HO, LTD.
"...has two advantages: one, it's amazingly fast..."
Guess not. ;-)
If you're comparing two sets of code vis. their MD5 sums, then won't that miss matching lines that differ by even one character - like, say, a space?
----
Not to be confused with Col.
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.
ESR shows us once again why exactly he has so much respect from the community. Well done, that man.
Anyway -- who cares? There's no question there are plenty of common chunks between Linux and SCO-owned source. And that there are ways to find them. The question is what they are (which SCO isn't saying) and what their common origin is and where that origin falls in the murky history of the Unix codebase. It's not as if anyone has been saying, "We're helpless in the face of this computational problem. If only there were a way to compare large bodies of text for common elements!"
Never mind that there are probably people who can compare both codebases in their heads.
Maybe he's made some major algorithmic breakthrough. (I doubt it but, but I'll leave that to the experts.) But this story is just him yapping again.
What I'm listening to now on Pandora...
ESR is ok you know, but lately he has just been doing lots of ranting and soapboaxing and no hacking.
Finally he comes out with some hack action. About time man, I was beginning to view him as just some big windbag who hacked a little back in the day. Well I still sorta do, but this is at least pretty cool, you know.
Article text follows:
SCO may not know origin of code, says Australian UNIX historian
By Sam Varghese
September 9, 2003
More doubts have been cast on the heritage of System V Unix code, which the SCO Group claims as its own, by an Australian who runs the Unix Heritage Society.
Dr Warren Toomey, now a computer science lecturer at Bond University, said today: "I'd like to point out that SCO (the present SCO Group) probably doesn't have an idea where they got much of their code. The fact that I had to send SCO (the Santa Cruz Organisation or the old SCO) everything up to and including Sys III says an awful lot."
He said that even though SCO owned the copyright on Sys III, a few years ago it did not have a copy of the source code. "I was dealing with one of their people at the time, trying to get some code released under a reasonable licence. I sent them the code as a gesture because I knew they did not have a copy," he said with a chuckle.
Dr Toomey's statements come a few days after Greg Rose, an Australian Unix hacker from the 1970s, raised the possibility that there may be code contributed by people, including himself, which has made its way into System V Unix and is thus being used by companies like the SCO Group.
Dr Toomey said this was one reason why the code samples which the SCO Group had shown at its annual forum had turned out to be widely published code.
SCO was unaware of the origins of much of the code and this "explains how they could wheel out the old malloc() code and the BPF (Berkeley Packet Filter) code, not realising that both were now under BSD licences - and in fact they hadn't even written the BPF code," Dr Toomey said.
He said that there was lots of code which had been developed at the University of New South Wales in the 70s which went to AT&T and was incorporated into UNIX without any copyright notices.
"At that time the development that was going on was similar to open source - the only difference was that the developers all had to have copies of the code licensed from AT&T," he said.
Dr Toomey, who served 12 years with the Australian Defence Force Academy, an offshoot of the University of New South Wales, before joining Bond University, said he had source code for Unices from the 3rd version of UNIX which came out in 1974 to the present day. "I don't have Sys V code but there are people with licences for that code who are members of the Unix Heritage Society. We can compare code samples any time," he said.
He agreed that the codebase of Sys V was a terribly tangled mess. "It is very difficult to trace origins now. There is an awful lot of non-AT&T and non-SCO code in Sys V. There is a lot of BSD code there," he said.
In March, the SCO Group filed a billion-dollar lawsuit against IBM, for "misappropriation of trade secrets, tortious interference, unfair competition and breach of contract."
SCO also claimed that Linux was an unauthorised derivative of Unix and warned commercial Linux users that they could be legally liable for violation of intellectual copyright. SCO later expanded its claims against IBM to US$3 billion in June when it said it was withdrawing IBM's licence for its own Unix, AIX.
IBM has counter-sued SCO while Red Hat Linux has sued SCO to stop it from making "unsubstantiated and untrue public statements attacking Red Hat Linux and the integrity of the Open Source software development process."
-----
Wordforge writing contest now open: deadline 2003-03-28
a world in progress...
Most people *I* know consider ESR to be a bloated windbag with a penchant for fanatical gunrights. He's regarded as pretty much being on the same level as the late Jon Katz.
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.
Bad boys rape our young girls but Violet gives willingly.
Bruce Perens:
Three. Three. And we'd better not risk another frontal assault. Their legal team is dynamite.
Linus:
Would it help to confuse it if we run away more?
Bruce Perens:
Oh, shut up and go change your firewall!
Alan Cox:
Let us taunt it! Darl may become so cross that he will make a mistake.
Bruce Perens:
Like what?
Alan Cox:
Well... ooh.
ESR:
Have we got bows?
Bruce Perens:
No.
ESR:
We have the Holy Hand Grenade.
Bruce Perens:
Yes, of course! The Holy Hand Grenade of Antioch! 'Tis one of the sacred relics Brother Richard carries with him.
Brother Richard! Bring up the Holy Hand Grenade!
MONKS: [chanting]
Pie Iesu domine, dona eis requiem.
Pie Iesu domine, dona eis requiem. Pie Iesu domine, dona eis requiem. Pie Iesu domine, dona eis requiem.
Bruce Perens: How does it, um-- how does it work?
ESR:
I know not, my liege.
Bruce Perens:
Consult the Book of Armaments!
RMS:
Armaments, chapter two, verses nine to twenty-one.
OPEN SOURCE ZEALOT:
And Saint Attila raised the hand grenade up on high, saying, 'O Lord, bless this Thy hand grenade that, with it, Thou mayest blow Thine enemies to tiny bits in Thy mercy.'
And the Lord did grin, and the people did feast upon the lambs and sloths and carp and anchovies and orangutans and breakfast cereals and fruit bats and large chu--
RMS:
Skip a bit, Brother.
OPEN SOURCE ZEALOT:
And the Lord spake, saying, 'First shalt thou take out the Holy Pin. Then, shalt thou count to three. No more. No less. Three shalt be the number thou shalt count, and the number of the counting shall be three. Four shalt thou not count, nor either count thou two, excepting that thou then proceed to three. Five is right out. Once the number three, being the third number, be reached, then, lobbest thou thy Holy Hand Grenade of Antioch towards thy foe, who, being naughty in My sight, shall snuff it.'
Richard:
Amen.
KNIGHTS:
Amen.
Bruce Perens:
Right!
One!... Two!... Five!
Alan Cox:
Three, sir!
Bruce Perens:
Three!
[sco dies]
Upper mangeement in most enterprises have a low level of technical knowledge. To them the thought of something called shredding coming anywhere near the 'voodoo' of software development would be abhorrent.
KDE GUI version should be called Krang since Shredder would obviously be used from the command line (shell). Maybe it should have helper apps called Bebop and Rocksteady. And if the need should arise, the project shouldn't fork...it should splinter.
By computing MD5 hashes of consecutive (overlapping) line triplets, the shred algorithm makes it easy to identify copied code, without ever seeing the actual code. This might be a perfect way for companies to allow a third party to compare code, without giving away any trade secrets in the process.
Of course, since MD5 is a very good cryptographic hash function, *any* one-bit change in the source will result in, on average, half of the bits in the result being flipped. So, this method of identifying copied code would only work if the code had never been run through an obfuscator. It would also be defeatable by running the source through a script to have its variable names search-and-replaced with similar names (such as replacing every variable name with a new name consisting of the old name plus "_newname")....
In short, this might be a useful technique for allowing a third party to look for trivial wholesale copying of code, but it would be useless for finding a motivated miscreant, determined to steal code without being caught.
Downside: Uh... it just came out... and it's making some big, big claims involving fuzzy logic. I think it's gonna need some testing first, eh?
Also, anybody else think it only works on larger sections of code than just say 10 lines?
SIG: HUP
I'm just glad that I finished college before they had this technology otherwise I might have been caught for cheating. Although I was really good at renaming variables.
Thanks ESR. You've just put a team of mathematicians at SCO who were somehow related to MIT out of their jobs.
You know the sad thing about all this? I can't tell the difference between the auto-generator or your average Slashdotter. Does this mean that the auto-generator passes the Turing Test, or that the average Slashdotter doesn't?
A deep unwavering belief is a sure sign you're missing something...
Chances are slim to none that a software company would allow it's "shredded" source code to be publicly released. What happens if the proprietary source is found to violate the GPL?
Proprietary (closed) source companies have a tremendous advantage over open source software when it comes to violating intellectual property. Who will ever know if they did it? A source code "comparator" eliminates that crucial advantage.
While I fully support ESR and the rest of the open source movement's defense of Linux against SCO, I have a feeling that this tool's results will not immediately be accepted by established media simply because of ESR's bias. A reporter looking into the SCO story who knows little about open source wouldn't trust a tool made by one side of the disagreement.
It seems very important to me that "third parties" and experts who are not an integral part of the open-source movement validate that comparator works as intended and is effective at detecting code similarities. Hopefully we'll see some articles on respected sites in the next week or so with conclusive analyses of comparator. Not to mention a chance for someone to use it on SCO's code!
Oh, and "Yes, I'm being deliberately vague and tantalizing" is quite funny.
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
Well, I was looking at ESR's description of the code (I haven't read the code yet), and it seems to say that he takes 3 line slices, MD5s them, then compares them for identical points. I'm sure he compensates for funky whitespace and whatnot like diff and patch do...
But if even one bit of the source is different, the MD5 hash will be quite different. So, the code slices have to be IDENTICAL. This is not a very good system because a simple find-replace could defeat it. A variable's name changed by one letter, or even capitalization, will defeat it.
Unless the code reveals much more complex tricks than ESR describes in the help file, this tool wouldn't be much use in the SCO case. Hell, it wouldn't be much use catching college class cheaters even.
Slashdot. It's Not For Common Sense
Comparing the hashes doesn't give you a definitive answer; it does, however, tell you where to look. Or which submitters to ask for clarification on the origins of potentially infringing code. That's more than we have now!
"Freedom means freedom for everybody" -- Dick Cheney
check out this research project coming out of berkeley CAP
Drop in the code you are interested in and it will tell you where its found in a bunch of open source stuff, including the linux kernel.
It gives software houses a way of publishing commercial code for copyright purposes. If you claim copyright on code, you can publish the MD5 shred sigs for the code. No one can rip you off, but you can enforce your rights in a court.
Even better - no one now has an excuse for not publishing. That means that we can make sure the kernel never comes within spitting distance of anyone else's property again. And if it does - well they should have published.
Now if SCO aren't willing to publish their MD5 shreds, then that can only be because they have no case. In which case - game over!
On the other hand, if they do, the world at large can then go through their published shreds and see exactly whose code SCO have been ripping off. Given the likely origins of those samples they exhibited a while back, I'd say that's likely to be quite a bit.
This looks like the best news for the war against everyone's favourite Stupidly Corrupt Organisation since the whole mess kicked off.
Don't let THEM immanentize the Eschaton!
Think of the chance that any given line of source code in an arbitrary program is repeated somewhere else in a large open source program such as the Linux Kernel. This is even more true if some degree of fuzziness is added to handle changes such as adding or removing spaces in insignificant places, removing comments, (and there are many other things like brace style which affect multiple lines so you might want to physically reformat between lines to a standard format....
If the number of lines is even only 1% that are found somewhere in the open source code base, I think a source who wants to keep their code base secret will have a big problem with someone computing the checksums. In reality, I wouldn't be suprised to see a much-higher percentage of lines leaked this way. And this is not the only way leaking can occur (think of application of simple cryptography).
I would not want to be the one publishing the checksums of the closed source due to possible legal liability. The checksums are a derived work in any case.
SCO was unaware of the origins of much of the code and this "explains how they could wheel out the old malloc() code and the BPF (Berkeley Packet Filter) code, not realising that both were now under BSD licences - and in fact they hadn't even written the BPF code," Dr Toomey said.
The SCO Group (not old SCO) hasn't written any code in SysV UNIX.
Anyway.. One could hope that when this is all over, the UNIX sources will be bought up from the carcass of SCOX and open-sourced, finally putting it out of its misery..
That is, as long as SysV UNIX doesn't have more stolen code in addition to the BSD code we all know about..
The sooner the zombie of UNIX is put to rest, the better for all the live Unices.
While Dark McBride and Chris Sontag shoot their mouths off, the community develops tools to finally make something clearer. :)
-Arnulf
int main()
{
printf("These source trees appear to be entirely different!\n");
return 0;
}
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.
What if this ESR tool runs and finds commonality, and the research shows that, in fact, SCO's rights were breached. Remember, this type of analysis is a two-edged sword. The purpose of this ESR is to remove doubt... but remember doubt could be removed either direction.
So, given that hypothetical, what would people here think? Would you forive SCO? Would you concede SCO's point, but think that SCO defended their rights in a very poor manner? (this, btw, is what I would probably do). Would you stick your fingers in your ears and refuse to accept the outcome, and believe in some vast -wing conspiracy?
Obviously, the Linx movement would carry on. I don't think the death of Linux is even worth discussion. Some recourse would happen, probably monetary damages, and the offending code would be removed.
My real curiosity is how people's attitudes or feelings would change (or not change) if it turns out SCO is right (however unlikely that is).
Sarcasm and hyperbole are the final refuges for weak minds
Have any of those techno-Rabbis run a comparison search with their "Bible Code" program on SCO? Did it come up with the phrases "bankrupt in 2004," "full of camel dung," and "Serpent of Utah"? How about running the "Bible Code" on Unix System V. code? Considering SCO's fondness for converting code over to Greek symbols for their presentations, converting to sanskrit, Hebrew or Aramaic shouldn't be a problem...
"Right now, somewhere in this world, Scott Baio is plowing a woman he doesn't love," - Peter Griffin, *Family Guy*
Compare C parse trees. That's right, look at the parse trees, use some fancy graph algorithm to compare the calculations and parse tree nodes.
Someone mod this up I think I'm on to something!
2 years and no mod points. Join reddit. Because openness is good.
Here is the reason: the people that "stole" SCO's code (if indeed that happened) probably were not acting with ill intent. They probably thought they were doing genuine, valid reuse, in which case, why hide it? Obfuscating runs the risk of introducing new bugs.
OSS programmers, even the ones that cut corners, are not malicious in my experience. There are honest mistakes made, because, well, they are lone programmers, not lawyers, or professional managers, or finacial experts, or whatever.
However, if code was diliberatly obfuscated, that would be very, very bad news for Linux. That shows that it was not an honest mistake, but the programmer knew something about the origins and they needed to be hidden. At the best, he could argue that he didn't think that it was an IP violation, he was just trying to make himself look better by not giving credit. The other side could argue he obviously new he was breaking the law.
Of course, as I said, I honestly don't think this case will come about. Even if code found its way in, I don't think it was a programmer say "Hey, I'm going to do this, but it is illegal, so I will cover my tracks."
Sarcasm and hyperbole are the final refuges for weak minds
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...
While IANAL, I don't suspect you are either. Copyright is not something that applies to ideas - it applies to expressions of ideas. I'll quote the Apple vs Microsoft case note by Joseph Meyers:
In other words, the question on the table is whether portions of the Linux kernel are a derivative work of SCO's code - not whether it uses SCO's ideas.It will just tell someone two trees are similar/identical. The important thing to prove in court is who copied from whom.
Speaking of BSD, a better way of doing this comes from Berkley too. It's a program called Moss that is used by many universities to detect plagarism in CS classes. I know from firsthand experience that this is a very powerful program. Unlike the shredding technique, things like changing variable names won't affect the comparsion value Moss returns. It even does a pretty good job of noticing changes like replacing for loops with while loops.
One disadvantage it does have though is that it won't work with the MD5 checksums, although I'm a bit skeptical of how well that would work anyway.
create a C language parser that reduced the C-code down to op codes
like gcc?
Finding obfuscated copied code is a difficult problem to solve. Presumably, SCO has put forth much effort into that, but they refuse to make public their claims.
Straight forward copying of code is much easier to find, and much easier to show is copying in a court. If we look at all the instances of duplicate code, and determine if they are license violations or not, it will be a start to making SCO go away.
Need a Catering Connection
...how to write good user interfaces. With coders like you we will never achieve complete world domination. The correct program is, of course, s.th. like this:
int main()
{
int i;
printf("Comparing source trees...\n");
sleep(2);
printf("Check started.\n");
for (i = 1000; i--;) {
printf(".");
sleep(1);
if (i % 100 == 0)
printf("\n%d0 percent remaining\n", i / 100);
}
printf("\n\nThese source trees appear to be entirely different!\n");
return 0;
}
THIS is exactly why Open Source works. It's not because of IBM or Red Hat or geeks from Finland. It's because people in the community are willing to step up to any challenge.
Thanks, ESR.
The global economy is a great thing until you feel it locally.
Pardon me, but a lot of you guys are missing the point of this comparator.
1) There are people out there with legit source licenses to SVR5 source trees. And not just Unix OEMs. Various people in large companies with SVR4/5 source licenses etc.
2) Such people cannot release the source code, and may (if paranoid of how they interpret 'derived works') not want to publish hashed MD5 codes of SVR5.
3) However, it should be possible for a legit SVR5 source licensee to publish openly a list of areas of code that are similar across trees, without that list being either A) a derived work, B) violating their NDAs (um, do check the fine print first though) and C) spending tons of their own, presumably expensive time, digging through stuff.
Then Linux advocates can then sift through the resulting large pieces of code and doublecheck/crosscheck the origins of it. At the very least, we'd have a public list of suspicious areas of Linux and could determine that certain parts are A) BSD-licensed, B) are verified as original by a known Linux coder, and C) don't fall into the above categories and remain 'suspicious'. This presumably is what ESR is referring to by "various persons will apply it in useful ways. Yes, I'm being deliberately vague and tantalizing". Let's say that its likely the percentages in A and B will be large.
Of course it's true that there could be code that this primitive tool doesn't catch. But SCO probably started their analysis by using tools like this also. Looking through millions lines of code by hand is no cakewalk, so one will inevitably start with code like this in such an investigation. (Unless one is concerned about one specific predetermined critical/sensitive piece of code.)
Oh, and the other thing about this tool that is nice IMHO? It demonstrates a "good faith" effort on the part of Linux advocates and coders to correct the problem -- despite the barriers raised by SCO (no code release except via NDA).
Finally, running this tool across a Linux and a BSD release should turn up some data that is both interesting and relevant for this dispute. I'm almost tempted to try that myself.
--LP
Why isn't this a press release?
If I go to Yahoo, and look at news related to SCOX, this doesn't show up. Here is the open source community trying to help find any misappropriated IP - and no one that doesn't read slashdot/eWeek will know about it!
Isn't there someone who subscribes to a wire service, that can issue a press release? In order to fight FUD, we have to get info out to people that don't read slashdot!!
Mike
Copyright is misapplied to source code. Either REVEAL THE SOURCE or you only get protection on that which you "publish" - namely, the binary.
Put up or shut up; no source, no copyright on the source. You won't share it, you don't need it protected.
They would be divulging SCO's biggest trade secret, that all their claims are just FUD.
Engineering is the art of compromise.
RTFM:
Name
comparator, filterator -- fast comparisons among large source trees
Synopsis
comparator -c [-d dir] [-o file] [-s shredsize] [-w] [-x] path...
[snip]
The -s option changes the shred size. Smaller shred sizes are more sensitive to small code duplications, but produce correspondingly noisier output. Larger ones will suppress both noise and small similarities.
[snip]
The -w causes all whitespace in the file (including blank lines) to be ignored for comparison purposes (line numbers in the output report will nevertheless be correct). This is recommended for comparing C code; among other things it means the comparison won't be fooled by differences in indent style.
Using the appropriate switches will address two of your points. I'm sure it wouldn't be extraordinarily difficult to modify the code to ignore other things such as string constants, variable names, etc.
Actually fetchmail proves that he can code.
This program just proves that md5 is not the correct hash for doing this kind of comparison. It is TOO GOOD of a one way hash, and will only return is positive if the lines being compared are 100% equal.
Finkployd
I cant dig up the slashdot post, but here is The Inquirer article from Jun 18th. Someone did this well before esr did.
Its not new, Its not esr's Idea, Its almost 3 months old!!!
I'm interested in algorithms that could be used to compare code. Moss and CAP from Berkeley are not interesting because the algorithm is secret (AFAIK).
What algorithms other than ESR's comparator are there? (I recall but can't locate a recent comment on Slashdot that said something like "most plagiarism detection programs used by professors use the XXXX algorithm".)
Download & read the source. Or just read the documentation.
Comparator has the capability (-w) to ignore whitespace while generating the hash, while at the same time tracking the actual line numbers for purposes of merging and reporting. In my experience, most code-copiers are dumb and/or lazy -- to get past ESR's tool, the code-copier would have to (a) realize that they're violating a license, (b) not care, (c) be smart enough to realize that a pure cut-and-paste might get caught, and (d) energetic enough to munge up the code logic and variables. While I'm sure there are people like that, I would argue that most of them wouldn't be interested in contributing the result to the community, and the code wouldn't get past Linus if they did. The more logical case is some one/company who believe that they have a legitimate right to copy code from one kernel to another (BSD -> Linux / Linux -> SysV / SysV -> Linux) and thus not feeling the need to cover things up. Either of the SCO User Group examples would fit this category.
We call it art because we have names for the things we understand.
He developed a Callcenter Training Utility for our company in the early 80's. It used genetic algorithms to generate simulated customer complaints that were _very_ realistic, even to the point of using sample voices to "whine". Of course, the helpdesk trainees hated it...
But hey, the mewling was featureful.
In order that the method should not be fooled by simple changes, at least the following is required
* White space must be ignored
* Comparison must be at the statement level, not the code line level
* Variable names must be replaced by standard placeholders
* Routine names, other than standard library calls, must be replaced by standard placeholders
* (Probably difficult) logic will be needed in the tool to detect and ignore noops: how do you deal with
The trouble is: a high proportion of the code sections thus simplified will fall into a relatively small number of possibilities, vulnerable to dictionary type attacks. Thus, most of the code could be reconstructed, though admittedly as obfuscated source code. IMHO this provides a valid objection to its use.
I think we are all missing a big point here. SCO registered their copyright in SysV. It was hard to do. They had to create a copy of the source code and file it with the Patent and Trademark Office. That puppy is there so that *we* can look at it. This is specifically *fair use*. It is there so that individuals can protect themselves by comparing what they have to what has been registered. No match means no problem. It just doesn't get any more *fair use* than that. Just have somebody nip up to the PTO, copy the registration for comparison purposes only, (really!) then do the comparisons. How hard is that? Yes, IAAL, but this is not legal advice. Hire your own mouthpiece.
Has anyone else tried to compile Eric's code?
/usr/bin/gcc -c -g main.c
>gcc --version
2.95.3
>make
main.c: In function `report_time':
main.c:311: parse error before `int'
main.c:312: parse error before `int'
main.c:316: `buf' undeclared (first use in this function)
main.c:316: (Each undeclared identifier is reported only once
main.c:316: for each function it appears in.)
main.c:317: `minutes' undeclared (first use in this function)
main.c:317: `seconds' undeclared (first use in this function)
make: *** [main.o] Error 1
Looks like Eric has been coding too much c++ or something. I'm not a c coder myself, so I might be wrong, but don't you have to declare all the variables in a block of c code before using them. In report_time, he doesn't seem to have followed that rule. Maybe he might check his code on a number of compilers before declaring he has "perfected it".
Eric here's my patch:
--- main.c 2003-09-10 00:28:37.000000000 -0300
+++ main.c.fixed 2003-09-10 00:29:55.000000000 -0300
@@ -306,12 +306,17 @@
if (mark_time)
{
- int elapsed = endtime - mark_time;
- int hours = elapsed/3600; elapsed %= 3600;
- int minutes = elapsed/60; elapsed %= 60;
- int seconds = elapsed;
+ int elapsed;
+ int hours;
+ int minutes;
+ int seconds;
char buf[BUFSIZ];
+ elapsed = endtime - mark_time;
+ hours = elapsed/3600; elapsed %= 3600;
+ minutes = elapsed/60; elapsed %= 60;
+ seconds = elapsed;
+
va_start(ap, legend);
vsprintf(buf, legend, ap);
fprintf(stderr, "%% %s: %dh %dm %ds\n", buf, hours, minutes, seconds);
I can see this tool becoming helpful for so much more than smashing SCO. Any situation where data comparison is useful, but the data itself must remain secret. All paranoid types (corporate or governmental) will love it. Lawyers could make much use of it.
And, given the dataset it generates, it could be extended to do other useful things such as detect redundant or cut-'n-pasted code, including bugs of the "pasted it in twice" sort.
So, you've downloaded Comparator, and run tests, then.
I didn't need to, the following is in the readme:
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.
You may want to check out "The Emperor Has No Clothes", a look at ESR's real code contributions.
http://www.talknerdy.org
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.
More importantly, get something like this accepted in a court of law as a legitimate way to do an initial assessment of code yet still preserve a litigants right to code privacy, and you are going to have not just MS but a number of big companies shaking in their boots. Not necessarily because they did steal anything but because they have to realize it is a possibility that one of their coders did without company knowledge. Doesn't matter, they are still liable.
But, get a method like this accepted in a court of law and you are going to see it used again. I think this has a huge potential to hurt closed software. And perhaps a potential to convince MS to stop funding SCO, perhaps even to apply pressure to get them to start backing down.
Okay, here it is (from the man page):
comparator works by first chopping the specified trees into overlapping shreds (by default 3 lines long) and computing the MD5 hash of each shred.
(Emphasis added)
There are only 10 types of people: those who understand decimal, those who don't, and, uh, 8 other types I forget.
It makes as much sense as anything SCO's said.
Hey, I just realized -- I'm typing this. I don't have to keep a straight face!
Sig:Why copyright isn't a fundamental human right
Eric's tool allows to compare larger and smaller chunks. Simple lines will easily match very often. Simple lines are not a problem. The problem is always lying in a sequence of lines. That's why you need overlapping sequences.
I don't know if the MD5 sums are a derivative work of the original source or not, but I would be inclined to think that they are.
Let's look at what the law says about fair use
Fair Use
The four factors are: (1) the purpose and character of the use, including whether such use is of commercial nature or is for nonprofit educational use; (2) the nature of the copyrighted work; (3) amount and substantiality of the portion used in relation to the copyrighted work as a whole; and (4) the effect of the use upon the potential market for or value of the copyrighted work.
It looks to me that under part (1), the MD5sums are a form of commentary or news reporting about the original work, not a replacement for the work. I don't know about (2). Under (3), the "amount" is definitely small, and the "substantiality" is low. And under (4), almost nobody who would buy the original work is going to substitute the MD5sum's instead, so the MD5sum's would have nil effect on the market for the original work.
So in my AC-IANAL opinion, distribution of the MD5sum's would be protected under American copyright law as a "fair use".
A lot of comments focus on the problems that a global search and replace will pose to the technique. I think we can improve the agorithm by doing the following:
What we are looking for here are pieces of code with the same structure: the same for loops, while loops, variable assignment, function names, and so on. The idea would be to substitute all literals by a standard placeholder, and then generate the md5 checksums on the block level (as somebody has previously suggested).
To be able to cheat this technique, a modification in the structure of the code is required. And in the case that exactly that has been done, it is arguably wether that can be considered copyright infringement.
But for changes of that kind, the burden of proof
is heavy and on the party alleging infringement.
The comparator tool isn't designed to try to catch
such deliberate obfuscation, because that would get
into murky territory near the boundary of expression and idea. Did you really think I failed to study the legal questions before I wrote this?
>>esr>>
The best use of this technology would to test the SCO LKP for stolen Linux code.
Confirming that SCO had incorporated Open Source code that they had access to under the GPL would destroy their credibility and open them up to countersuits. The process would only have to reveal enough similarities to have subpoenas ordered for the actual code involved. Then we could prove the theft with SCO own source code.
I suspect that those who know that Linux code was used to create LKP would come forward once the code has been discover and posted for all to see.
Even a potential Lawsuit is just another reason to write grooooovy software.. *evil grin*
GO ESR!!
-- All That's Evil in the Geek Space
Did your momma have any children that learned to think?
Source code gets no copyright protection: corporations keep their source as a "trade secret" and only get protection on the executable. It is illegal to redistribute (copy) the executable, and the source is entirely within their control (and their responsibility). No real "furtherance of the arts" is accomplished except within the limited scope of usage of the tool itself. If a work is infringed at the source level, therefore, it is (nearly) impossible to prove without revealing "trade secrets" and, therefore, exposing the company to further risk.
Source code gets copyright protection (as constitutionally mandated)
Corporations have to register the source code, and therefore are given fulll protection on both works. It is just as illegal to redistribute (share) the source beyond the scope allowed by the rights holder, and if a work is infringed there is no risk to the rights holder in defending the work. "Furtherance of the arts" is addressed, as well as the rights of the work's creator.
Corporations are allowed "copyright" on works they do not share.
It becomes nearly impossible for libeled parties to defend themselves, but "rights holders" are free to make claims as they see fit. Which gives "rights holders" basically free reign to make accusations which they may never be forced to address in court, and leaves victims nearly defenseless until the (very slow) court gets around to addressing the issue. Neither "furtherance of the arts" nor protection of (libeled) rights holders is served, since the more powerful party remains free to withold (copyrighted) "evidence" that no one is allowed to see.
How does this system serve rights holders whose works may have been infringed upon, but are forced from the marketplace by another "rights holder" with more money? How does that system serve the public interest? How does it promote progress?
Can you answer any of these questions using sound logic?