Dear colleagues, We are pleased to announce that we have published the source code used by the RIPE NCC for the RPKI back-end (the RPKI core) under the 3-Clause BSD licence on Github: https://github.com/RIPE-NCC/rpki-core <https://github.com/RIPE-NCC/rpki-core> The RPKI core is the RIPE NCC's software for creating and maintaining RPKI objects based on the registry's current status and publishing these in the repositories. The RIPE NCC hosts the authoritative repository internally. We use the repository on Github to publish the source code externally. The first commit is identical to the source code in the RIPE NCC's internal repository at the time of that commit. The changes between releases are squashed and published to this repository on deployment, and the `main` branch reflects the code used by the production CA. We encountered several challenges while preparing this project for an open-source release. The main challenges were that the system uses proprietary elements that were part of the revision history and cannot be made public. Furthermore, it was not possible to review all historic commits. We plan to present our challenges while open-sourcing this project at RIPE 84. If you have any questions about this change, please contact the RIPE NCC's RPKI team at rpki@ripe.net <mailto:rpki@ripe.net>. Kind Regards, Bart Bakker Senior Software Engineer RIPE NCC