Privacy-Preserving eID Derivation to Self-Sovereign Identity Systems with Offline Revocation

Digital identities play a vital role in an increasingly digital world. These identities often rely on central authorities to issue and manage them. Central authorities have the drawback of being a central trusted party, representing a bottleneck and single point of failure with exclusive control of identity-related
data. Self-sovereign identity (SSI) tackles those problems by
utilizing distributed ledger technology and making users the
sovereign owners of their identity data. Nevertheless, SSI, as
recent technology, still lacks qualified identity data. This is
especially a problem since sensitive services like eGovernment
or banking services require identity data issued by a qualified
identity provider; thus, SSI-based identities cannot be used for
these services.
In this paper, we propose a concept for deriving identity data
from an existing identity system into an SSI in a fully privacypreserving
way by additionally supporting offline verification.
This way, we enable a chain of trust from the existing identity
system to the SSI system by introducing a novel trust model.
Our concept utilizes novel cryptographic primitives to support
efficient and privacy-preserving identity showing as well as revocation.
To underline the feasibility of our concept, we implement
a proof system and benchmark the related use cases.