Ceremony Operating ENvironment (COEN)

COEN is a live operating system consisting of:

• A custom Debian GNU/Linux Live CD
• Key Management Tools: Legacy
• Key Management Tools
• The AEP Keyper PKCS#11 library
• Assorted utilities

Table of Contents

• Reproducible COEN ISO image to enhance Root Zone DNSSEC Key Signing Key ceremony trustworthiness
  • What are reproducible builds?
• Acknowledgments
• Requirements for building the COEN ISO image
  • Disabling SELinux
• Building the COEN ISO image
• Tested Platforms

Reproducible COEN ISO image to enhance Root Zone DNSSEC Key Signing Key ceremony trustworthiness

The reproducible COEN ISO image provides a verifiable process to generate the same hash any time the COEN ISO image is built, which consequently increases trustworthiness in the DNSSEC Key Signing Key (KSK).

What are reproducible builds?

Quoted from https://reproducible-builds.org

Reproducible builds are a set of software development practices that create an independently-verifiable path from source to binary code.

The motivation behind the Reproducible Builds project is therefore to allow verification that no vulnerabilities or backdoors have been introduced during this compilation process. By promising identical results are always generated from a given source, this allows multiple third parties to come to a consensus on a "correct" result, highlighting any deviations as suspect and worthy of scrutiny.

Acknowledgments

This project is made possibly by:

• The Reproducible Builds project
• Debian serving as trust anchor
• Debuerreotype a reproducible, snapshot-based Debian rootfs builder (License)
• The Amnesic Incognito Live System (License)

Requirements for building the COEN ISO image

Warning: In order to generate a reproducible COEN ISO with a matching hash, Docker/Podman requires administrator privileges, and suppressing container and operating system security protections. Consequently, testing should occur in a suitable environment.

To build the COEN ISO image:

• Use Docker (recommended) or alternatively Podman
• Execute commands as administrator, root, or with sudo
• Execute container with full capabilities --privileged which is required during ISO generation to mount/share, create device nodes, chroot into the new rootfs, and disable security kernel protections e.g. AppArmor and SELinux
• Completely disable SELinux rather than operating with permissive mode because the generated image will not be reproducible otherwise. In addition, --privilege mode reportedly disables SELinux with --security-opt label=disable, but in testing, without manually disabling SELinux prior to ISO generation including a restart to reload the kernel, the resulting ISO will not match the hash. The differences with SELinux enabled are benign, but obviously result in a different hash

Disabling SELinux

If you are running a Red Hat based distribution, including RHEL, CentOS, and Fedora, it is likely the SELinux security module is installed.

Execute sestatus and check the output for the current SELinux mode.

If you see enforcing or permissive for "Current mode", SELinux is enabled and enforcing rules or is enabled and logging rather than enforcing errors.

Note: before proceeding, be aware disabling SELinux also disables the generation of file contexts, so an entire system relabeling is required if SELinux is enabled again.

To disable SELinux:

• Edit /etc/sysconfig/selinux or /etc/selinux/config depending on your distribution
• Set the SELinux parameter to disabled
• For the changes to take effect, you need to reboot the machine, since SELinux is running within the kernel
• Check the status of SELinux using the sestatus command

Building the COEN ISO image

Run make to see the execution options.

Running make all or make podman-all will build a container image in Docker or Podman. Then, a container will execute a bash script to build the COEN ISO, and if the build succeeds, the resulting COEN ISO will be copied into the host directory.

If permission errors are encountered executing make all or make podman-all as a non-root user, try sudo make all or sudo make podman-all

Final hash result should match with the following:

405d7c76c114feb93fcc5345e13850e59d86341a08161207d8eb8c395410c13a  coen-1.0.0-amd64.iso

Tested Platforms

Testing has been performed in the following environments:

OS	Docker	Podman	SELinux	AppArmor
Debian 11.6 bullseye	23.0.1, build a5ee5b1	-	-	Enabled
Arch Linux	23.0.1, build a5ee5b1dfc	-	-	-
Fedora 37	23.0.1, build a5ee5b1	4.4.2	Disabled	-
AlmaLinux 9.1	23.0.1, build a5ee5b1	4.2.0	Disabled	-
CentOS 7.9.2009	23.0.1, build a5ee5b1	-	Disabled	-
MacOS Ventura 13.2.1	20.10.23, build 7155243	-	-	-
openSUSE Tumbleweed	20.10.23-ce, build 6051f1429	-	-	Enabled
Windows 10	20.10.22, build 32ac30b	-	-	-
Ubuntu 22.04.2 LTS	20.10.17, build 100c70180f	-	-	Enabled