So I finally had time to look through the K3B code.

Here's the brief rundown of how their code works:
1) They use the KDE library object KMD5 for the MD5 sum.  This allows you to read the data in chunks and pass them to the sum object, and that's what they do.
2) They read the device file (i.e. fopen("/dev/hdb", ...); ) using KDE QFile libraries
3) They read the raw device data in 2K blocks
4) They use this data to calculate the MD5 sum.

They do something very similar for ISO files, basically reading the ISO straight in and calculating the MD5 sum from the data.

It looks like you should be able to run an MD5 sum on the device file (/dev/hdb, NOT /dev/hdb1), and on the ISO and they should match (unless QFile is doing something weird here, and I don't think it does).

==Joseph++

Joseph Sinclair wrote:
> I know k3b does a md5sum on the disk after a burn if you turn on verify media.  It checks this against a md5sum of the iso file.  I'm sure you could find out how they do it by reading the code (isn't the GPL great?).
> I'd look into it, but I'm short on time for the next few weeks.  If nobody else does (please post results here if you do), I'll try to look into it late next month.
> 
> ==Joseph++
> 
> Dazed_75 wrote:
>> I downloaded ubuntu-6.06.1-dvd-i386.iso and verified the md5sum against
>> that
>> listed at the download site.  I then burned the DVD and got no errors.  One
>> nice thing ubuntu has in the 6.06 release is a menu option (on booting the
>> CD/DVDs) to verify the CD/DVD content.  When I tried this, it shows errors
>> for some files.
>>
>> Surely there could be a problem with the burn, but I was wondering if there
>> is any way to md5sum the DVD?  The only thing I could think of is to make a
>> .iso from it and I do not know if that would even be expected to reproduce
>> the original iso and match its sum.
>>
>> I realize I probably need to burn another DVD, but the question is still a
>> valid one.
>>
>>
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