I do not believe that this is correct. When you take the MD5SUM of the cdrom DEVICE (not mounted file system) you are taking the MD5SUM of the whole cdrom image which should be the same as the ISO that created it. I'm not 100% on this. It may be that the image gets padded or something like that. I think what Curtis is talking about is the difference between the ISO and the actual mounted CD file system and yes those definately are different. So again I think you can simply do:
cdrecord dev=0,0,0 test.iso md5sum test.iso md5sum /dev/scd0 (or whatever) I think the output from the two MD5 sums should be the same. Does anyone know for sure on this. I'm pretty sure I've done this before and I believe it makes sense that this would work. Jeff On Wed, Jan 21, 2004 at 12:25:53PM -0700, Curtis Sloan wrote: > On Wed, 2004-01-21 at 11:43, Jason Louie wrote: > > But is this producing the same MD5 checksum directly from the CD as > > the ISO? > > I'm not sure if I understand what you are asking, so let me rephrase the > question and you can correct me if I'm misunderstanding: > > "Is the MD5 checksum of the CD (i.e. /dev/cdrom) the same as the MD5 > checksum of the .iso file (before it was burned)?" > > If this is the question you are asking, then the answer is no. They > will always be different. > > The answer lies is in the way the MD5 algorithm works. It produces a > unique 128-bit checksum for any given arrangement of bytes. > > In this case, the arrangement of the bytes in an ISO file is distinctly > different than that of the exact same bytes laid out in a filesystem > (i.e. after burning). The MD5 algorithm doesn't care that they are the > same bytes, since (from the algorithm's perspective) the single ISO file > is fundamentally different than the collection of files taken as a > whole. One MD5 will be a "fingerprint" of an ISO file, the other of an > entire filesystem. The difference can seem semantic, but viewed from an > algorithm's point of view, it can make sense. > > This may account for apparent discrepancies in MD5s (if I understood > your question correctly). > > HTH, > Curtis > > > > > I've seem lots of examples on the web on the process of verifying CDs > > burnt from ISOs but I can't seem to reproduce the results. I only > > have access to a burner on a Win system and I'm wondering if that is > > the reason why the MD5s are different. > > > > Pete wrote: > > > Linux commandline burning works for me... > > > > > > http://www.yolinux.com/TUTORIALS/LinuxTutorialCDBurn.html > > > > > > There are a few examples of commands to copy CDs > > > > > > Peter > > > > > > Jason Louie wrote: > > > > Has anyone been able to verify the *burned* copy of the ISO? Also > > > > what programs are you guys using for the burning? I'm using Nero > > > > on a Win system. I have lots of distros that I would like to > > > > share but I don't feel good about having them available when I'm > > > > not sure if they're good. I haven't been able to get matching > > > > results with doing an MD5 check on the CD so I was wondering if > > > > anyone has been getting better results. > > > > > > > > -- > > > > > > > > Jason Louie BSc. CPSC > > > > Web Applications Developer > > > > Sorex Software Inc. > > > > [EMAIL PROTECTED] > > > > > > > > > > > > __________________________________________________________________ > > > > _______________________________________________ > > > > clug-talk mailing list > > > > [EMAIL PROTECTED] > > > > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > > > > > > > > > > ____________________________________________________________________ > > > _______________________________________________ > > > clug-talk mailing list > > > [EMAIL PROTECTED] > > > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > > > > > > > -- > > > > Jason Louie BSc. CPSC > > Web Applications Developer > > Sorex Software Inc. > > [EMAIL PROTECTED] > > > > ______________________________________________________________________ > > _______________________________________________ > > clug-talk mailing list > > [EMAIL PROTECTED] > > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > > > _______________________________________________ > clug-talk mailing list > [EMAIL PROTECTED] > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > -- Jeff Clement http://jclement.ca
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