Hidden Issuer Anonymous Credential

Abstract

Identity Management Systems (IMS) allow users to prove characteristics about themselves to multiple service providers. IMS evolved from impractical, site-by-site authentication, to versatile, privacyenhancing Self Sovereign Identity (SSI) Frameworks. SSI frameworks often use Anonymous Credential schemes to provide user privacy, and more precisely unlinkability between uses of these credentials. However, these schemes imply the disclosure of the identity of the Issuer of a given credential to any service provider. This can lead to information leaks. We deal with this problem by introducing a new Anonymous Credential scheme that allows a user to hide the Issuer of a credential, while being able to convince the service providers that they can trust the credential, in the absence of a trusted setup. We prove this new scheme secure under the Computational Diffie Hellman assumption, and Decisional Diffie Hellman assumption, in the Random Oracle Model. We show that this scheme is efficient enough to be used with laptops, and to be integrated into SSI frameworks or any other IMS.

A Comprehensive Approach to User Delegation and Anonymity within Decentralized Identifiers for IoT

“…Bosk et al identifies the problem that a traditional DID exposes the Issuer's identity to all participants, leading to data breaches. They propose a new anonymous credential using NIZK, a modified PS (Pointcheval Sanders) Signature, and Aggregate, allowing the Holder to hide the Issuer of credentials while ensuring trust in a trustless setting [33]. However, it is not secure when it comes to Sybil attacks, as attackers can create multiple fake identities and exert undue influence within the DID.…”

“…When creating a single VP based on n VCs for a delegation to provide delegation to m Delegatees, the existing schemes [21,22,32,33] generate with the size being the number of VC for delegation (n) * the number of Delegatee (m) + n * m * VC for delegation. The existing scheme requires m separate original VCs rather than VCs for delegation.…”

Private and Mutual Authentication Protocols for Internet of Things

“…Private authentication was introduced by Abadi [17], where the identity of each protocol participant will not be revealed to its peers unless authorized by the participant. There are several techniques that can be applied to achieve private authentication, e.g., secret handshakes [18], that allow members of a group to identify each other privately; hidden credentials [19] that enable the sender to send encrypted messages; mechanisms that ensure that only recipients who meet certain access policies can decrypt the message; and attribute-based encryption schemes [20] that support fine-grained access control over decryption capabilities.…”