Peppol for the masses

Peppol is an EU-backed e-Invoicing network which uses a top-down certification infrastructure to establish trust between the sender and the receiver of an invoice. In the "Peppol for the Masses!" project, we will implement Peppol in PHP (so far only Java and C# implementations are available), and package its core components (the AS4 sender and the AS4 receiver) as a Nextcloud app, so that users of the popular Nextcloud personal cloud server can send and receive invoices over AS4 directly into their self-hosted server.

Due to the top-down nature of Peppol's trust infrastructure, it's not possible to self-host a node in the Peppol network unless you go through a reasonably heavy certification process. Therefore, we will extend our implementation with support for self-hosted identities, using the "WebID" identity pattern which was popularized by the Solid project. We will also develop a re-signing gateway which replaces the signature on an AS4-Direct invoice with a Peppol-certified signature. In a follow-up project, we will also host an instance of this re-signing gateway and make it available free of charge, similar to how the LetsEncrypt project has made TLS certificates available free of charge.

This project will lower the (cost) barrier for machine-readable cryptographically-signed e-Invoicing messages, and at the same time increase the sovereignty of end-users, towards a human-centric internet of business documents.