I like to create my own distro based on Ubuntu. I may modify the source of some packages. When I read intellectual-property-policy of Ubuntu, I noticed the following rule.

Any redistribution of modified versions of Ubuntu must be approved, certified or provided by Canonical if you are going to associate it with the Trademarks. Otherwise you must remove and replace the Trademarks and will need to recompile the source code to create your own binaries. This does not affect your rights under any open source licence applicable to any of the components of Ubuntu. If you need us to approve, certify or provide modified versions for redistribution you will require a licence agreement from Canonical, for which you may be required to pay. For further information, please contact us (as set out below).

^{Source: https://ubuntu.com/legal/intellectual-property-policy}

Consider that I have recompiled the Ubuntu package source and built my own repository: I actually pull the source apt-get source, build deps apt-get build-dep and use dpkg-buildpackage to compile. Once .deb is generated, I host it in my local private apt-repository.

In the future, if I have to legally prove that I have indeed recompiled the Ubuntu package source, how can I prove it? Do I have to inject any custom tags in generated .deb or binary inside the .deb? I checked for the custom tags (just to find some leads) in MintLinux distro's .deb but I couldn't able to see any custom tags.