Generating a new ubuntu-keyring .deb to sign ISO CD

Tue Oct 25 13:15:41 UTC 2016

On 25 October 2016 at 12:00, Stefani Seibold <stefani at seibold.net>
> wrote:
> > 
> > Hi,
> > 
> > i want modify an existing ubuntu 16.10 iso image to provide a new
> > kernel for a server device which is currently in development and
> > yet
> > not on the market.
> > 
> > I trying to build a new ubuntu-keyring.deb to sign my modified
> > packages
> > in the ISO Image. I followed the instructions provided by
> > Ubuntu  (http
> > s://help.ubuntu.com/community/InstallCDCustomization), but without
> > success.
> > 
> > When i follow the instructions in the chapter "Generating a new
> > ubuntu-
> > keyring .deb to sign your CD" i get a lot off errors:
> > 
> > dpkg-buildpackage -rfakeroot -m"Myname <myname at myhost.net>"
> > -k7F6D4417D881EFC3E7FA02E636F2F7B4F8A2CAC9
> > dpkg-buildpackage: info: source package ubuntu-keyring
> > dpkg-buildpackage: info: source version 2016.09.19
> > dpkg-buildpackage: info: source distribution yakkety
> > dpkg-buildpackage: info: host architecture amd64
> >  dpkg-source --before-build ubuntu-keyring-2016.09.19
> >  fakeroot debian/rules clean
> > test -f keyrings/ubuntu-archive-keyring.gpg
> > rm -f foo foo.asc *.bak *~ */*~ debian/files* debian/*substvars
> > rm -rf debian/tmp debian/ubuntu-keyring-udeb
> >  dpkg-source -b ubuntu-keyring-2016.09.19
> > dpkg-source: warning: no source format specified in
> > debian/source/format, see dpkg-source(1)
> > dpkg-source: info: using source format '1.0'
> > dpkg-source: info: building ubuntu-keyring in ubuntu-
> > keyring_2016.09.19.tar.gz
> > dpkg-source: info: building ubuntu-keyring in ubuntu-
> > keyring_2016.09.19.dsc
> >  debian/rules build
> > make: Nothing to be done for 'build'.
> >  fakeroot debian/rules binary
> > test -f keyrings/ubuntu-archive-keyring.gpg
> > test root = "`whoami`"
> > gpg --no-default-keyring --keyring /usr/share/keyrings/debian-
> > keyring.gpg --decrypt SHA512SUMS.txt.asc | sha512sum -c -
> > gpg: Signature made Mon Sep 19 19:22:17 2016 CEST
> > gpg:                using RSA key CAC2D8B9CD2CA5F9
> > keyrings/ubuntu-archive-keyring.gpg: OK
> > keyrings/ubuntu-archive-removed-keys.gpg: OK
> > keyrings/ubuntu-keyring-2004-archive.gpg: OK
> > keyrings/ubuntu-keyring-2004-cdimage.gpg: OK
> > keyrings/ubuntu-keyring-2012-archive.gpg: OK
> > keyrings/ubuntu-keyring-2012-cdimage.gpg: OK
> > keyrings/ubuntu-master-keyring.gpg: OK
> > gpg: BAD signature from "Dimitri John Ledkov <xnox at ubuntu.com>"
> > [unknown]
> > gpg --no-default-keyring --keyring /usr/share/keyrings/debian-
> > keyring.gpg --decrypt md5sums.txt | md5sum -c -
> > gpg: Signature made Sat May 19 03:30:13 2012 CEST
> > gpg:                using RSA key 393587D97D86500B
> > keyrings/ubuntu-archive-keyring.gpg: FAILED
> > gpg: Good signature from "Colin Watson <cjwatson at chiark.greenend.or
> > g.uk>" [unknown]
> > gpg:                 aka "Colin Watson <cjwatson at debian.org>"
> > [unknown]
> > gpg:                 aka "Colin Watson <cjwatson at ubuntu.com>"
> > [unknown]
> > gpg:                 aka "Colin Watson <cjwatson at canonical.com>"
> > [unknown]
> > gpg: WARNING: This key is not certified with a trusted signature!
> > gpg:          There is no indication that the signature belongs to
> > the owner.
> > Primary key fingerprint: AC0A 4FF1 2611 B6FC CF01  C111 3935 87D9
> > 7D86 500B
> > md5sum: WARNING: 1 computed checksum did NOT match
> > debian/rules:92: recipe for target 'checkkeyrings' failed
> > make: *** [checkkeyrings] Error 1
> > dpkg-buildpackage: error: fakeroot debian/rules binary gave error
> > exit status 2
> > 
> > Any idea? Is there a instruction manual or a how to which gives me
> > detailed instructions how i can modify an existing iso image?
> > 
> > I am not sure it this is the right mailing list for my question,
> > please
> > feel free to tell me the right one ;-)
> > 
> 
> I added these extra validation checks in the ubuntu-keyring package
> to
> make sure that signing keys are not modified by accident, and to make
> sure that checksums are signed by semi known-to-be-good keys.
> 
> To bypass these checks comment out commands under the
> "checkkeyrings:" target.
> 
> NB! Do make sure you ship your key as a key fragment in
> /etc/apt/trusted.gpg.d/ as apt-key is no longer called, and from
> yakkety and up signing keys must be shipped as individually exported
> keys in /etc/apt/trusted.gpg.d directory.
> 
> Ideally d-i would support key fragments just like installed systems
> can, then one wouldn't need to rebuild ubuntu-keyring at all.

This brings me one step further.

Now i can build the ubuntu-keyring packages. But the installation fails
i copy the results to cd:

cp ./ubuntu-keyring_2016.09.19_all.deb cd/pool/main/u/ubuntu-keyring/ubuntu-keyring_2016.09.19_all.deb
cp ./ubuntu-keyring-udeb_2016.09.19_all.udeb cd/pool/main/u/ubuntu-keyring/ubuntu-keyring-udeb_2016.09.19_all.udeb
apt_ftparchive -c config-rel release cd/dists/yakkety > cd/dists/yakkety/Release
gpg --yes --no-default-keyring --keyring ./ubuntu-archive-keyring.gpg -a --default-key <mykey> --output cd/dists/yakkety/Release.gpg --detach-sig cd/dists/yakkety/Release
cd cd; md5sum `find ! -name "md5sum.txt" ! -path "./isolinux/*" -follow -type f` > md5sum.txt; cd ..
genisoimage -o output.iso -r -J -no-emul-boot -boot-load-size 4 -boot-info-table -b isolinux/isolinux.bin -c isolinux/boot.cat ./cd

The cd installation will abort with

apt configuration problem
An attempt to configure apt to install additional packages from CD
failed.

The debug output on vt4 show me

gpgv: Signature made Tue ....
gpgv:  using RSA key
gpgv: Can't check signature: No public key
 .
 .
apt-setup: W: Signature verification failed for /media/cdrom/diss/yakkety/Release.gpg

I verified the install ubuntu-archive-keyring.gpg on my build host with

gpgv --keyring ./ubuntu-archive-keyring.gpg cd/dists/yakkety/Release.gpg cd/dists/yakkety/Release
gpgv: Signature made Tue Oct 25 14:55:11 2016 CEST
gpgv:                using RSA key 
gpgv: Good signature from "Signing Key Namexx <xxx at yyy.com>"

So it looks good for me. Any idea?