Switching to AS4 for market communication in the energy industry

Market Communication in the German electricity sector is moving to AS4

| | Product Manager Business Unit Utilities, SEEBURGER
Market communication in the German electricity sector is moving to AS4

+++ UPDATE March 2023: UPDATE: BSI published Version 1.1.2 of the Certificate Policy for the Smart Metering PKI

At the beginning of March 2023, the German Federal Office for Information Security (BSI) published version 1.1.2 of the Certificate Policy for the Smart Metering PKI (SM-PKI-Policy) on its website.

With this version and the incorporation of the participants in market communication in the “SM-PKI-Policy,” another important milestone has been reached on the path to implementing AS4 communication.

The policy defines the participants in market communication as external market participants (EMT – German: externe Marktteilnehmer). Furthermore, different rules for the certificate contents have been defined for the participants in market communication. For example, in addition to EMT, the common name in the certificate must also contain MAK to indicate that it is a certificate for AS4 market communication with smart meter PKI.


+++ UPDATE JULY 2022: Changeover to AS4 in market communication

On 31 March 2022, the Bundesnetzagentur (BNetzA in eng. German Federal Network Agency) published the directive on the introduction of AS4 in market communication (directive on the future safeguarding of electronic market communication for electricity): On 02 June 2022, the documents prepared by BDEW on the AS4 profile and regulations on the transmission method were put out for consultation by the BNetzA. Updated documents from the BSI are not yet available.

But what does this mean for you?

AS4 will become mandatory for certain communications in the electricity sector. Specifically, this will apply to:

  • business processes for supplying electricity to customers (GPKE/ Geschäftsprozesse zur Kundenbelieferung mit Elektrizität )
  • processes relating to electricity generators (MPES/ Marktprozesse für erzeugende Marktlokationen Strom)
  • processes for switching meter point (WiM/ Wechelsprozesse im Messwesen) and
  • processes for balancing electricity supply (MaBiS/ Marktregeln für die Durchführung der Bilanzkreisabrechnung Strom)

Timetable for the implementation of AS4 in market communication:

  • From July 2022, all market participants must start project planning for the new transmission method in market communication.
  • From October 2023, all market participants are obliged to fulfil the technical requirements for the exchange of the specifications for the new transmission path.
  • By April 2024, all market participants must have completed the changeover to the new communication method.

Challenges AS4 in market communication:

According to the BNetzA, there are no plans for a mandatory, central address service for retrieving AS4 communication data. All market participants are obliged to switch their communication with all market partners to AS4 between 01 October 2023 and 31 March 2024 without exception. The BNetzA does not have any guidelines for this conversion phase.


Market communication is essential for the digital transformation of the energy industry. Being able to smoothly exchange data and information between market players is particularly important for guaranteeing an uninterrupted energy supply. However, let’s start from the beginning. What does market communication look like now in the German energy sector? What requirements and specifications are there for data transmission? And what impact will adopting AS4 have on market communication? Read on to discover what you need to know about the changes to market communication.

The market processes for supplying, balancing and billing energy are crucial to ensuring that further processes in the sector run smoothly. To this end, the key to successful digital transformation in the German energy industry is working, future-proof and secure market communication (commonly known in German as MaKo).

Changes in demand and in the way that energy is generated, together with the development of an energy information network and new European developments pose new challenges to the current market processes. On the one hand, the sector needs effective, frictionless processes for supply and billing. Equally, it needs stronger data and information interexchange to ensure a seamless, balanced energy supply. On top of these, new business areas are emerging, such as the control and aggregation of flexibility volumes, e-mobility, and digital products and services which need to be supported by standardised, digital market communication to be available to a mass audience.

It’s important not to underestimate the relevance of how data is transmitted between market players. To this end, the general growth in digital communication and the higher security specifications entering market communication in Germany’s liberalised energy sector have required changes to data transmission.

Last but not least, data security and data protection also place considerable demands on data transmission.

Where are we now?

Since market communication was formalised in 2006 in the newly liberalised German energy sector, members have mainly used e-mail to exchange data. This has been adapted and made more secure over the years, not least through requiring encryption and an electronic signature from 2020.

There are many advantages to e-mail communication, as well as serious disadvantages.


  • A known technology
  • As a rule, available in any organisation
  • Can be acquired as a service
  • Robust
  • Scalable


  • Messages may be delayed in arriving, or not arrive at all
  • Senders can be blocked
  • Non-standardised error messages
  • responses with errors are not machine readable
  • Delivery time can be unpredictable

Since there is no acknowledgement or confirmation of an e-mail arriving or being picked up, this method of communication is not really suitable for time-critical processes. Therefore, now a CONTRL message is used as proof of receipt.

However, the changes in the energy market have led to more and more time-critical processes where delayed communication can be problematic. Switching to a synchronous means of transmission eliminates these problems.

What is AS4?

AS4, i.e. Applicability Statement 4, is a secure messaging protocol. It is based on AS2 and OASIS ebMS 3.0 (Electronic Business Messaging Service) and contains many of the established functions that were already in AS2.

This protocol starts by establishing a secure connection over the internet. It then sends an encrypted message, and generates a confirmation response from the receiver once the message has been received. If an error occurs, both parties are informed.

AS4 is already being used in processes for the long-distance gas network operator ENTSO-G, for E-Delivery and Peppol.

Moving to a new transmission protocol

The Bundesverband der Energie- und Wasserwirtschaft (BDEW) (eng. German Federal Association of the Utility and Water Industry) had already set out an intended move to the AS4 protocol in their position paper BDEW-Roadmap Daten- und Marktkommunikation back in 2017.[1]

Their main aims are to:

  • increase the quality of the market processes
  • limit costs increases for market communication
  • further develop market communication processes to support new areas and business models
  • targeted improvement of the technology underpinning market communication

This laid the foundation for switching to AS4 as the communication protocol for market communication. The Bundesnetzagentur (BNetzA) (eng. Federal Network Agency for Electricity, Gas, Telecommunications, Post and Railway) has since specified these objectives in its consultation procedure on the future safeguarding of electronic market communication for the electricity sector.

Determination process to transfer market communication to AS4

On 16th September 2022, the BNetzA launched the consultation phase for determining a secure basis for electronic market communication in the electricity sector (BK6-21-282).

The aim is to ensure a high level of security, in particular confidentiality and integrity, by employing new   technological standards in the area of electronic market communication. The ability for the market participants in the energy industry to securely and reliably exchange data is indispensable for effective electronic market communication.

The BNetzA have decided that from 1st October 2023, market communication for the German electricity sector shall be transmitted over AS4 with Transport Layer Security (TLS)[2]. This encompasses

  • process documents GPKE, MPES, WiM and MaBiS,
  • exchanging schedules
  • processing Redispatch 2.0

The smart metering public key infrastructure (PKI) will be used alongside the encryption specifications defined by the German Bundesamt für Sicherheit in der Informationstechnik (BSI) (eng. German Federal Office for Information Security) to ensure communication is secure.

The aim is to achieve the following:

  • increase the security level in electronic market communication
  • ensure interoperability with European standards

This decision draws on the following:

  • BSI TR-03109-4[3]: This document describes the architecture of SM-PKI, its users and their roles, and defines the data structure and management of certificates.
  • BSI TR-03116-3[4]: This document describes the specific cryptographic algorithms and how to use them. Of particular significance is the use of elliptical brain pool curves. SEEBURGER already supports these algorithms.
  • BSI Certificate Policy for the smart metering PKI: The Certificate Policy includes details of operational, organisational and technical security requirements. At the forefront is communication between a smart meter gateway and various actors. Of particular significance is the use of hardware security modules (HSM) for storing private keys. SEEBURGER already supports the most common of these HSMs.

Your road map for implementing AS4

Looking at the deadline to move market communication to AS4, we can reasonable expect the following interim milestones:

  • determination process to run until beginning of 2022
  • specifications to be published by 1st April 2022
  • software solutions to be implemented by 1st April 2023
  • changeover by 1st October 2023

Optimise your market communication with AS4 and join the digital future in the energy industry now!

[1] cf. BDEW: Roadmap Daten- und Marktkommunikation [Roadmap for data and market communication] (accessed 12.01.2022).

[2] cf. Bundesnetzagentur: Konsultation eines Festlegungsentwurf zur künftigen Absicherung der elektronischen Marktkommunikation Strom. (accessed 12.01.2022).

[3] Bundesamt für Sicherheit in der Informationstechnik: TR-03109-4 Smart-Metering-PKI. Public-Key-Infrastruktur für Smart-Meter-Gateways. (accessed 12.01.2022).

[4] Bundesamt für Sicherheit in der Informationstechnik: BSI TR-03116-3 Kryptographische Vorgaben für Projekte der Bundesregierung Teil 3. (accessed 12.01.2022).

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Alexander Schmidt

Written by:

Alexander Schmidt has been with SEEBURGER since 2001. He has been part of the Utilities Business Unit since 2006, where he initially looked after various large customers from the energy sector before moving to Product Management in 2018. Since then, he has been in charge of SEEBURGER solutions for the energy market. He enjoys spending his free time with his family or pursuing his hobby, darts, together with friends.