Service-centric Networking

Prof. Dr. Axel Küpper






Office TEL19
Building TEL
Address Ernst - Reuter - Platz 7
10587 Berlin


Kindly note - no office hours will be provided on May 25, 2022!

Please be informed that our office hours will be provided every Wednesday from 12:00 - 13:00. Please register at the secretariat.



S. Rodriguez Garzon, H. Yildiz and A. Küpper, Decentralized Identifiers and Self-sovereign Identity in 6G, 2022.

One of the key challenges for mobile network operators in the future will be to bring together a wide range of new players in the mobile network market under a common umbrella and to orchestrate their innovative technologies to provide economically viable and seamless mobile connectivity to the mobile subscribers. With each new player, be it a cloud, edge or hardware provider, the need for interfaces with secure authentication and authorization mechanisms increases, as does the complexity and operational costs of the public key infrastructures required for the associated identity and key management. While today's centralized public key infrastructures have proven themselves to be technically feasible in confined and trusted spaces, they do not provide the required security once centralized identity providers must be avoided, e.g., because of limited cross-domain interoperability or national data protection legislation, and state-dependent certification authorities can't be commonly trusted, e.g., because of geopolitical reasons. Recent decentralized identity management concepts, such as the W3C proposed recommendation of Decentralized Identifiers, provide a secure, tamper-proof, and cross-domain identity management alternative for future multitenancy 6G networks without relying on identity provider or certification authorities. This article introduces the concept of Decentralized Identifiers together with the principles of Self-sovereign Identity and discusses opportunities and potential benefits of their application and usage for cross-actor and privacy-preserving identity and key management in the next mobile network generation 6G.
M. Westerkamp and A. Küpper, SmartSync: Cross-Blockchain Smart Contract Interaction and Synchronization, 2022.

Cross-Blockchain communication has gained traction due to the increasing fragmentation of blockchain networks and scalability solutions such as side-chaining and sharding. With SmartSync, we propose a novel concept for cross-blockchain smart contract interactions that creates client contracts on arbitrary blockchain networks supporting the same execution environment. Client contracts mirror the logic and state of the original instance and enable seamless on-chain function executions providing recent states. Synchronized contracts supply instant read-only function calls to other applications hosted on the target blockchain. Hereby, current limitations in cross-chain communication are alleviated and new forms of contract interactions are enabled. State updates are transmitted in a verifiable manner using Merkle proofs and do not require trusted intermediaries. To permit lightweight synchronizations, we introduce transition confirmations that facilitate the application of verifiable state transitions without re-executing transactions of the source blockchain. We prove the concept's soundness by providing a prototypical implementation that enables smart contract forks, state synchronizations, and on-chain validation on EVM-compatible blockchains. Our evaluation demonstrates SmartSync's applicability for presented use cases providing access to recent states to third-party contracts on the target blockchain. Execution costs scale sub-linearly with the number of value updates and depend on the depth and index of corresponding Merkle proofs.
S. Rodriguez Garzon, H. Yildiz and A. Küpper, Towards Decentralized Identity Management in Multi-stakeholder 6G Networks, 2022.

Trust-building mechanisms among network entities of different administrative domains will gain significant importance in 6G because a future mobile network will be operated cooperatively by a variety of different stakeholders rather than by a single mobile network operator. The use of trusted third party issued certificates for initial trust establishment in multi-stakeholder 6G networks is only advisable to a limited extent, as trusted third parties not only represent single point of failures or attacks, but they also cannot guarantee global independence due to national legislation and regulatory or political influence. This article proposes to decentralize identity management in 6G networks in order to enable secure mutual authentication between network entities of different trust domains without relying on a trusted third party and to empower network entities with the ability to shape and strengthen cross-domain trust relationships by the exchange of verifiable credentials. A reference model for decentralized identity management in 6G is given as an initial guide for the fundamental design of a common identity management system whose operation and governance is distributed equally across multiple trust domains of interconnected and multi-stakeholder 6G ecosystems.


H. Yildiz, C. Ritter, L. T. Nguyen, B. Frech, M. M. Martinez and A. Küpper, "Connecting Self-Sovereign Identity with Federated and User-centric Identities via SAML Integration" in 2021 IEEE Symposium on Computers and Communications (ISCC), IEEE, 2021. pp. 1-7.

Self-sovereign identity provides a feasible alternative to login via username and password through an identity provider to access digital services. It allows identity subjects to control and own their data. Although this is an appealing approach, it requires a whole new infrastructure with almost no dependencies on the existing ones. We designed and implemented a solution that combines an existing federated identity access management solution with the new approach by enabling authentication via self-sovereign-identity-based credentials while the identity provider retains verification and communication with the service provider via Security Assertion Mark Up Language. Thanks to the standardized federated systems in the German higher education domain, the solution not only enables a smooth transition to self-sovereign identities but can also be easily transferred to other universities using the same federated identity framework.
A. Küpper, "Decentralized Identifiers and Self-Sovereign Identity - A New Identity Management for 6G Integration?" in 2021 IEEE International Conference on Joint Cloud Computing (JCC), IEEE, 2021. pp. 71-71.

Decentralized Identifiers (DIDs) and Self-Sovereign Identity (SSI) are emerging decentralized identity solutions. DIDs allow legal entities like organizations to create and fully control their identifiers while building the necessary infrastructure for SSI, enabling entities like persons, organizations, or machines to fully control and own their digital identities without the involvement of an intermediate central authority. DIDs are identifiers that are used to reference entities unambiguously and, together with DID Documents stored in a verifiable data registry, establish a new, decentralized public-key infrastructure. An SSI-based digital identity may be composed of many different claims certified by an issuer. Examples are the identity holder’s name, age, gender, university degree, driving license, or other attributes. What makes SSI unique compared to other identity management solutions is that the users keep their digital identities in storage of their choice and thus determine their distribution and processing.With this privacy-by-design approach, the emergence of DIDs and SSI can shape the architecture of the future Internet and its applications, which will impact the future of mobile networks. While 5G networks are currently being rolled out, a discussion about the new capabilities of 6G networks, which are still in the distant future, has long since begun. In addition to even faster access, shorter delays, and new applications, features such as human-centricity, data protection, and privacy are being addressed in particular in the discussions. These latter points make DIDs, SSI, and related concepts and architectures promising candidates for 6G adoption.The talk gives a brief introduction to DIDs and SSI and then discusses the benefits and drawbacks the integration of these technologies into 6G may have. Furthermore, the talk identifies different use cases and identifies the system components and functions of cellular networks affected by a 6G integration.

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