JSON-LD signatures and validations

[IDM.TSA.E1.00019] Proof Chains in JSON-LD

JSON-LD proof chains [LD.Proofs] SHOULD be supported to link multiple entities to the same data,
when proof sequences are required. This can be useful for notary counter-signing a proof that
had been created on a document. It MUST support signing and verifying the VCs.

Example:

{
    "@context":
    [
        "https://www.w3.org/2018/credentials/v1",
        "https://www.w3.org/2018/credentials/examples/v1"
    ],
    "title": "Hello World!",
    "proofChain":
    [
        {
            "type": "Ed25519Signature2018",
            "proofPurpose": "assertionMethod",
            "created": "2019-08-23T20:21:34Z",
            "verificationMethod": "did:example:123456#key1",
            "domain": "example.org",
            "jws": "eyJ0eXAiOiJK...gFWFOEjXk"
        },
        {
            "type": "RsaSignature2018",
            "proofPurpose": "assertionMethod",
            "created": "2017-09-23T20:21:34Z",
            "verificationMethod": "https://example.com/i/pat/keys/5",
            "domain": "example.org",
            "jws": "eyJ0eXAiOiJK...gFWFOEjXk"
        }
    ]
}