  A key challenge for mobile network operators in 6G is to bring together and
orchestrate a variety of new emerging players of today's mobile ecosystems in
order to provide economically viable and seamless mobile connectivity in form
of a multi-stakeholder service. 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 identity and key
management. While today's centralized public key infrastructures have proven to
be technically feasible in confined and trusted spaces, they do not provide the
required security for access control once centralized identity providers must
be avoided because of limited cross-domain interoperability, national data
protection legislation, or geopolitical-strategic reasons. Recent decentralized
identity management concepts, such as the W3C recommendation of Decentralized
Identifiers, provide a secure, tamper-proof, and cross-domain identity
management alternative for future multi-stakeholder 6G networks without relying
on centralized 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-domain and privacy-preserving
identity and key management in 6G networks.
