Use cases of fep-8b32: Object Integrity Proofs

ActivityPub
23

I should actually clarify something here. The so called hack’s purpose is for stuff to remain valid JSON-LD, not to break compatibility with JSON-LD processors as suggested above.

In particular:

{
    "@context": [
        "https://www.w3.org/ns/activitystreams",
        "https://www.w3.org/ns/credentials/v2"
    ],
  "actor": "https://first.example/users/first",
  "cc": [
    "https://second.example/users/second",
    "https://first.example/users/first/followers"
  ],
  "id": "https://first.example/users/first/statuses/1097854/activity",
  "object": {
    "@context": [
        "https://www.w3.org/ns/activitystreams",
        "https://www.w3.org/ns/credentials/v2"
    ],
    "id": "https://second.example/users/second/statuses/109724234853",
    "type": "Note",
    "content": "Hello world",
    "proof": {
        "type": "DataIntegrityProof",
        "cryptosuite": "eddsa-jcs-2022",
        "verificationMethod": "https://second.example/users/alice#ed25519-key",
        "proofPurpose": "assertionMethod",
        "proofValue": "z3sXaxjKs4M3BRicwWA9peyNPJvJqxtGsDmpt1jjoHCjgeUf71TRFz56osPSfDErszyLp5Ks1EhYSgpDaNM977Rg2",
        "created": "2023-02-24T23:36:38Z"
    }
  },
  "published": "2023-01-31T19:11:46Z",
  "to": ["https://www.w3.org/ns/activitystreams#Public"],
  "type": "Announce",
   "proof": {
        "type": "DataIntegrityProof",
        "cryptosuite": "eddsa-jcs-2022",
        "verificationMethod": "https://first.example/users/first#ed25519-key",
        "proofPurpose": "assertionMethod",
        "proofValue": "fixme",
        "created": "2023-02-24T23:36:38Z"
    }
}

is an invalid json-ld documents. As we will want to sign objects containing signed objects. This is unacceptable.

Finally, by changing the enveloping context to

    "@context": [
        "https://www.w3.org/ns/activitystreams",
        "https://www.w3.org/ns/credentials/v2",
         {
           "object": {
             "@id": "as:object",
             "@type": "@json"
           }
         }
    ],

one can resolve this problem.