Target: Debian with secure boot on USB

Some Links I base my progress on

Steps so far:

# download debian8.4-netinstall (official link)
wget http://cdimage.debian.org/debian-cd/8.4.0/amd64/iso-cd/debian-8.3.0-amd64-netinst.iso
mkdir debNet   # extract iso
bsdtar -C debNet -xf debian-8.4.0-amd64-netinst.iso

ls debNet
>autorun.inf  doc        install      pool                 README.txt
>boot         efi        install.amd  README.html          setup.exe
>css          firmware   isolinux     README.mirrors.html  tools
>debian       g2ldr      md5sum.txt   README.mirrors.txt   win32-loader.ini
>dists        g2ldr.mbr  pics         README.source

As described by rodsbooks,I should now

  • rename EFI/BOOT/bootx64.efi to EFI/BOOT/grubx64.efi
  • move shim.efi to EFI/BOOT/bootx64.efi
  • move MokManager.efi to EFI/BOOT/
  • make some nice magic with keys and signing, tadaa, you're done.

To make an bootable USB, I take the following steps

xorriso -as mkisofs \
    -isohybrid-mbr /usr/lib/syslinux/isohdpfx.bin   \
    -c boot.cat \
    -b $relative_isolinuxbin \
    -no-emul-boot -boot-load-size 4 -boot-info-table -eltorito-alt-boot \
    -e boot/grub/efi.img -no-emul-boot -isohybrid-gpt-basdat \
    -o $outISO $sources
sudo dd if=debian8.4.0.modified.iso of=/dev/sdb

If I had any idea what I was doing before (just getting uefi to run), I would have seen that I use efi.img. So it took some time experimenting with debNet/efi/boot to find that adding or changing of even deleting this directory does not change booting at all. (maybe deleting the directory corrupts the installation - didnt try - but not the booting)

So, I finally understood I have to change debNet/boot/grub/efi.img. So here's my main question so far - how do I create this efi.img for my needs?

dd if=/dev/zero of=efi.img bs=1k count=3000
mkfs.vfat efi.img
sudo mount efi.img img_mountpoint/

and copying the bootloaders as described in rodsbooks does not seem to work.

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