Tangle Linked Data Proofs

ld-proofs enables Linked Data Proofs on the Tangle. Powered by IOTA Identity and IOTA Streams.

Installation

npm install @tangle-js/ld-proofs

How it works

Aligned with the W3C Linked Data Proofs proposed specification this library allows the generation and verification of Linked Data Proofs associated to plain messages or JSON(-LD) documents. Different kinds of Linked Data Proofs can be generated:

EdDSA (Ed25519) Signatures over plain messages
Linked Data Signatures for JSON-LD Documents Ed25519Signature2018
Linked Data Signatures for JSON Documents JcsEd25519Signature2020
Linked Data Proofs anchored to the Tangle (using the anchors library). The proof's type is IotaLinkedDataProof2021. This type of proof anchors to the Tangle a Linked Data Signature together with a reference to the signed document.

The identities and their corresponding public key materials follow the W3C DID specification.

API

Linked Data Signature generation (Ed25519 over JSON(-LD))

const did = "did:iota:2pu42SstXrg7uMEGHS5qkBDEJ1hrbrYtWQReMUvkCrDP";
// Default node is IF Chrysalis Nodes
const signer = await IotaSigner.create(did, node?);

const jsonLdDocument = {
    "@context": "https://schema.org",
    "type": "Organization",
    "name": "IOTA Foundation"
};

const options: ISigningOptions = {
    verificationMethod,
    secret: privateKey,
    signatureType: SignatureTypes.ED25519_2018 
};
// Obtains a Linked Data Signature
const ldSignature = signer.signJson(jsonLdDocument, options);

Linked Data Signatures verification (Ed25519 over JSON(-LD) objects)

// The document includes the former document and the Linked Data Signature
const signedDoc = {
    "@context": "https://schema.org",
    "type": "Organization",
    "name": "IOTA Foundation",
    "proof": {
        "proofValue": "3JTS3UaJc2aS2rxkQ1Z4GEs9HjvASnm3e2s5VT5pS8voGEBodWBBd6P7YUmq8eN92H9v1u2gmqER7Y6wXhgcywYX",
        "type": "Ed25519Signature2018",
        "verificationMethod": "did:iota:2pu42SstXrg7uMEGHS5qkBDEJ1hrbrYtWQReMUvkCrDP#key",
        "proofPurpose": "dataVerification",
        "created": "2021-06-21T13:29:25.976Z"
    }
};

// True if verified. False otherwise. 
const verified = await IotaVerifier.verifyJson(signedDoc);

Linked Data Proofs generation (anchored to the Tangle)

See the anchors library and the IotaSigner class.

const anchorChannel = /* Instantiate an anchoring channel */
const signer = /* Instantiate a signer */
const proofGenerator = IotaLdProofGenerator.create(anchoringChannel, signer);
// Generates the Linked Data Signature and anchors it to the Tangle generating 
// an Iota proof
const tangleProof = await proofGenerator.generate(jsonLdDocument, {
    verificationMethod,
    secret,
    signatureType: SignatureTypes.ED25519_2018,
    anchorageID: anchoringChannel.firstAnchorageID
});

Linked Data Proofs verification

const anchoredDoc = {
    "@context": "https://schema.org",
    "type": "Organization",
    "name": "IOTA Foundation",
    "proof": {
        "type": "IotaLinkedDataProof2021",
        "verificationMethod": "did:iota:yUxEqDGgL2WF4sQq2TEzdmDjDkRsHKL5TcLWrdAjmb4",
        "proofPurpose": "dataVerification",
        "proofValue": {
            "channelID": "1761e16e50dd6c95f7155979b5691b0a4390559f6ff0287a297cc2ae818312c40000000000000000:7bc48fb8fe5dccdb81dd5dcd",
            "anchorageID": "e7b123ed4c6a803538a52233",
            "msgID": "1fa6dde995dd6320bc0f7958",
            "msgIDL1": "e5b1edf2935329e6dd04692e9ec37581b9fcc5954e5f8450e7f9306933a6e2d5"
        },
        "created": "2021-07-01T10:21:50.338Z"
    }
};
const verified = await IotaLdProofVerifier.verifyJson(anchoredDoc);

Signing plain messages

Only EdDSA (Ed25519) is supported.

// The node is optional and by default will be IF mainnet nodes
const node = "https://chrysalis-nodes.iota.org";

// The DID contains the public cryptographic materials used by the signer
const did = "did:iota:2pu42SstXrg7uMEGHS5qkBDEJ1hrbrYtWQReMUvkCrDP";
const signer = await IotaSigner.create(did);

// Plain message to be signed
const message = "hello";

// Method declared on the signer's concerned DID document
const method = "key";
// Private Key in base58
const privateKey = "privateKeybase58";

const options: ISigningOptions = {
    signatureType: SignatureTypes.PLAIN_ED25519,
    verificationMethod: method,
    secret: privateKey
};

const signingResult = await signer.sign(Buffer.from(message), options);
console.log("Signature: ", signingResult.signatureValue);

Verifying plain messages

const options: IVerificationOptions = {
    verificationMethod: "did:iota:2pu42SstXrg7uMEGHS5qkBDEJ1hrbrYtWQReMUvkCrDP#key",
    // Node is optional and it is IOTA's mainnet by default
    node: "https://chrysalis-nodes.iota.org"
};

const verified = await IotaVerifier.verify(message, signatureValue, options);