Checksumming an entire CD/DVD

I'm publishing a set of documentation to be delivered on CD. My Company's European production manager is concerned that he has no way to verify that the data on the discs he produces is correct. He asked that either I send him a CD to compare to, or he sends me a disc and I do the first article inspection. This would negate all the advantages of sending the ISO file instead of the physical CD.

My first thought is to use md5 hashes. I could take the sum of the ISO I created, and he can compare the sum of his copy of the ISO, and to the physical disc.

However, I can't seem to figure out how to get the md5sums utility to hash the disc as a whole rather than reporting the sums of each file on the disc. Then, should I even expect the sum of the ISO to match the sum of the disc's contents?

The solution I come up with must work on both Windows XP and Windows 7.

daxlerod

Posted 2011-07-20T16:14:52.467

Reputation: 2 575

What is wrong with running md5sum against the individual files on the disk? You could include a copy of md5summer on your disk, and send him the sums via email or something.

– Zoredache – 2011-07-20T17:16:50.707

I would send him the iso with checksum, and have him burn and verify it with his software. – Joe Internet – 2011-07-20T18:54:38.020

I should have mentioned initially, what we are doing is first article inspection from our production house. They are sending my counterpart a proof of the CD and the printed documentation that comes with it. Unless the burning software can do an after-the-fact verification, that sort of thing won't work. – daxlerod – 2011-07-21T11:50:21.650

Answers

Corz's checksum

http://corz.org/windows/software/checksum/

Best utility I've used for checksums, IMO. It will checksum a whole disk like you ask, unlike other incompetent programs. . .

edit:

In case you aren't reading the comments, there was a question about creating an aggregated hash of an entire folder tree. I've only used two checksum programs. MD5deep and Corz's checksum. So the only program that I know of that will create an aggregated hash of a folder tree is Corz's checksum, which is linked in my answer.

surfasb

Posted 2011-07-20T16:14:52.467

Reputation: 21 453

This one's nice, though I'm pretty content with this one: http://www.nirsoft.net/utils/hash_my_files.html. Thanks!

– Isxek – 2011-07-20T18:37:16.437

It's a portable application FYI. But ya. Don't fix it if it ain't broke. – surfasb – 2011-07-20T18:40:23.877

This creates checksums for each for each file and lists them all in a single text file. That looks nice. However, how does it account for files in one location, and not the other? Say my iso has foo.bar, but it isn't on the disc, and the disc (somehow) has baz.bar. When I validate the checksums, will it give errors on extra and missing files? – daxlerod – 2011-07-21T11:55:08.967

The format is space delimited. RelativePath+FileName [ ] Checksum. So if baz.bar is not on a child node, you'll need to specify an absolute path. It will only give errors for individual files. – surfasb – 2011-07-21T12:03:01.797

Let me make sure I understand: Say Joe Blow at the printers decided to add a file, baz.bar, to the physical CDs he manufactures. When my overseas contact validates the checksums, no error will be given. If Joe Blow deletes foo.bar, an error will be given. I know neither scenario is likely, but these are the questions I will have to answer. – daxlerod – 2011-07-21T13:29:47.283

Aye. You are correct. Most programs I know of like checksumz and md5deep do not do an aggregate checksum. One, they are very innacurrate and two they take forever. My advice is to burn a copy of the checksum file on the CD or send it to him separately( ala two factor authentication). – surfasb – 2011-07-21T18:43:19.300

Ok, I'm wrong. There is actually a way to make an aggregated hash. md5deep won't do it, but corz's checksum will. (the one I linked). I noticed in the ini file that he has a setting called a "root" hash. That's basically what you are looking for. An aggregated hash of an entire folder tree. – surfasb – 2011-07-21T18:56:44.607

The "root" hash doesn't actually create a aggregate hash. It creates a file with the hashes for each file. (Unless I did it wrong. I'll try again.) I would have no problem with this, if it can account for files added and subtracted. – daxlerod – 2011-07-21T23:36:03.150

Odd, my root hash changed if I moved files out of the folder. . . – surfasb – 2011-07-21T23:47:36.457

You can use dd for Windows to extract an iso from the CD, and then run md5sum on the retrieved image.

Sunny

Posted 2011-07-20T16:14:52.467

Reputation: 921