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I have already burned the DVD from the ISO for Kubuntu 15.10.iso image. ISO verifies fine. But I read we are to verify the DVD also. I ran:

$ sha256sum /dev/cdrom
758061ca3be30128dca74e3f73b5dd6e76fb5047c0c4e0743f22786fb0a02dd0  /dev/cdrom

The only thing is, the download site tells you how to do the checksum, but there is no listing of what the hash response should be. I checked the entire site I believe.

Can someone please share the correct hash response for Kubuntu 15.10 64bit ISO? And provide link to where it is officially listed please.

marked as duplicate by Ravan, muru, Pilot6, Charles Green, Eric Carvalho Dec 22 '15 at 15:29

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The sha256sum hash result of your /dev/cdrom must the same as the hash of your ISO

sha256sum /dev/cdrom

dd if=/dev/cdrom | head -c $(wc -c < kubuntu-15.10*.iso) | sha256sum -

and

sha256sum kubuntu-15.10-desktop-amd64.iso

must return the same result

the correct hash = 9e5eb424eabfd9b2d193d8c34eca7b48ad944b90c0de0bdcbb638563c14c4d2b Source

  • You are correct I believe. I got that correct hash for the ISO, but 758061ca3be30128dca74e3f73b5dd6e76fb5047c0c4e0743f22786fb0a02dd0 /dev/cdrom for the DVD hash. I event ran it again and same hash. Im using xfburn in Xubuntu. Maybe I need a different burner software. Im out of ideas. I will mark you correct though, after a while. Wanna see what others say. – Norman Bird Dec 21 '15 at 23:52
  • It is also not very clear that the hash for the DVD and iso should be the same. – Norman Bird Dec 21 '15 at 23:56
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    An ISO file (or ISO image) is a perfect representation of the whole disc. so they must have the same hash at all times. I googled a bit and it seems xfburn have trouble finalizing a disc/closing session after a burn , which makes the DVD useless and not readable. – user257256 Dec 22 '15 at 0:03
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    Hmmm. could not get right hash for dvd in xfburn so I tried K3B and it givem me d7559c90efece2b38021804cc34011eb2cb161fff2afe6894985083bd41232d5. Ill open a seperate question for this I guess Thanks again @Houssem-Guesmi – Norman Bird Dec 22 '15 at 0:27
  • @houssemguesmi No. Hashing a device is just wrong. Not what you do. – user323419 Dec 22 '15 at 1:05
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The checksums of ISO and DVD should be the same. But most optical media return more bytes than were recorded. This alters the checksum result, of course.

You need to restrict reading from DVD to the size of the ISO, See in https://www.debian.org/CD/faq/#verify the third paragraph "The problem with the verification of written optical media ..."

The same amount of bytes as in the ISO file must yield the same checksum. Else the DVD is not good.

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