The talk is about the implementation of secure boot in NixOS, a Linux distribution. Secure boot is a process that ensures that the operating system being booted is authentic and has not been altered. However, NixOS's model is different from other Linux distributions, making it challenging to implement secure boot. The talk presents Lanzarote boot tool, which re-signs the system's boot and kernel files whenever NixOS rebuilds, and the Lanzarote boot stub, which embeds the path and cryptographic hash of the kernel and initrd files. The talk also discusses the boot specification RFC and how it contributes to booting the right kernel and initrd files, and how users can onboard secure boot. Finally, the speaker talks about future plans to make secure boot more user-friendly and collaboration channels for contributing to the implementation.