  Digital Identities are playing an essential role in our digital lives. Today,
used Digital Identities are based on central architectures. Central Digital
Identity providers control and know our data and, thereby, our Identity. Self
Sovereign Identities (SSI) are based on a decentralized data storage and data
exchange architecture, where the user is in sole control of his data and
identity. Most of the issued credentials need the possibility of revocation.
For a Central Digital Identity, revocation is easy. In decentral architectures,
revocation is more challenging. Revocation can be done with different methods
e.g. lists, compressed lists and cryptographic accumulators. A revocation
method must be privacy preserving and must scale. This paper gives an overview
about the available revocation methods, include a survey to define
requirements, assess different revocation groups against the requirements,
highlights shortcomings of the methods and introduce a new revocation method
called Linked Validity Verifiable Credentials.
