How good are MD5sums?

[kevinc]

I finally got my Kubuntu 9.04 Alternate i386.iso file using bit torrent on Intrepid.
K3B gave me a different MD5sum to the download site.
Hmmm. What to do? Blank CD's are cheap and it took me 12 hours in the internet cafe over nearly two weeks to get the image, so I burned it anyway.

Then I selected the check CD option and it told me everything was OK. I had one image once that had one error and it failed to install - hardly surprising.

As I have a dual boot, why not try it on my spare partitions. Installed it, maybe slightly easier than previous versions. Reboot - everything worked perfectly. I've tried everything and can't find any problems.

Any ideas?

[dibl]

Re: How good are MD5sums?

Then I selected the check CD option and it told me everything was OK.

You can't trust that method, unfortunately.

The md5 sum on the image file itself needs to be a match to the one that is on the site where you downloaded the image from. That's the only valid test on a downloaded image file.

[kevinc]

Re: How good are MD5sums?

You can't trust that method, unfortunately.

The md5 sum on the image file itself needs to be a match to the one that is on the site where you downloaded the image from. That's the only valid test on a downloaded image file.

I had read that before, but I was interested to see if it worked, probably motivated by the fact that I didn't want to wait another two weeks to get a fresh image.
In the past, I used to download images, burn them and install them with a high success rate (possibly due to CD writer maximum speed 8*).

In this case the MD5sum was totally different, and yet I'm using it now.