aka One Time Merkle Proofs for less correlatable Credentialsaka One Time Revealable Credentials byJoe Andrieu (Legendary Requirements),Frederic Martin (myDid),Imad El Aouny (myDid),Lohan Spies (DIDx / IOHK) License CC-BY 4.0 Group credentials offer an opportunity for privacy preserving verification of group membership. Same Credential to a all members of a group We want to issue the exact same VC to all members of a group so that each VC reveals no information about who is a member of the group. We propose to do this by issuing a VC with subject id of the Merkle root of cryptographic identifiers controlled by various group members. Upon presentation of that VC to a Verifier, group membership can be verified by testing that the cryptographic id that signs the VP is in the merkle tree. We create a did:merkle and merkleProof proof type so that the VC is issued to did:merkle and the VP includes TWO proofs. One is the traditional tamper-evident signature. The second is the merkleProof. For additional correlation protection, the issuer may include multiple cryptographic ids for each recipient, allowing recipients to use different proofs with different verifiers. This solution is cryptosuite agnostic and does not depend on novel cryptography such as group signatures (or ZKP methods).

{ "@context": { "id": "https://hackmd.io/y90zzprAScCIaj41JcCQmg", "@protected": true, "citizenship": { "@id": "https://hackmd.io/y90zzprAScCIaj41JcCQmg#citizenship", "@type": "https://schema.org/addressRegion" } } }

{ "@context": { "id" : "https://hackmd.io/8ldzJzjXRmCw18fxNHzZcw", "merkleProof" : { "@id" : "https://hackmd.io/8ldzJzjXRmCw18fxNHzZcw#merkleProof" } } }

{ "@title" : "iid document " "@context" : [ "https://www.w3.org/ns/did/v1", "https://w3id.org/security/suites/ed25519-2020/v1" ], "id":"did:cosmos:ixo:123" }