Easy one? MD5

[Wakou]

If I change the filename of a file, does its MD5 Checksum change?
If NOT why not?
What about the SHA?

If you have not dozed off yet......
I downloaded a Linix ISO install DVD on a friend's machine.
I burnt it to a DVD disk, but not thinking, I burnt it to a bootable, I wanted the ISO.
SO I re-packed the files from the burnt disk to ISO format and saved them.
It saved as a different name (ie was openSUSE-11.1-DVD-i586.iso, is now SU1110.001.ISO)
BUT the MD5 checksum is still correct
How so?
Can I still use it?
I have since changed the name again, to su.iso
Still OK?

[bigtomrodney]

I burnt it to a DVD disk, but not thinking, I burnt it to a bootable, I wanted the ISO.
SO I re-packed the files from the burnt disk to ISO format and saved them.
It saved as a different name (ie was openSUSE-11.1-DVD-i586.iso, is now SU1110.001.ISO)

That's your problem right there.

The file you get, although it may be associated with programs such as WinRAR or similar archive programs, is the ISO file. You cannot recreate the ISO from its contents without modifying the boot catalog for your new disc. You see, the boot catalog has to reside within the first 512 bytes of the disc image so you cannot just repack it.

This is in fact the reason for distributing as ISO files rather than the contents. If you have the original image I would start there, otherwise you may be back to downloading it again.

[D-cat]

BUT the MD5 checksum is still correct

md5sum calculates the sums based on the contents of the file. The file name is of no consequence, it's not part of the calculation.

If you burn an ISO to disc, then recapture that disc to ISO on the device level, then no data is altered and thus the md5 sum will be the same. (It's like backing up a hard drive via image) If however, you try to re-create the ISO from the disc in file mode, then Big Toms's post above applies in its entirety.