Castor

@hyperledger/identus-sdk v7.0.0

---

@hyperledger/identus-sdk / overview / Castor

Class: Castor

Defined in: src/castor/Castor.ts:42

Castor is a powerful and flexible library for working with DIDs. Whether you are building a decentralised application or a more traditional system requiring secure and private identity management, Castor provides the tools and features you need to easily create, manage, and resolve DIDs.

Castor

Implements

• Castor

Constructors

Constructor

new Castor(apollo: Apollo, extraResolvers: ExtraResolver[], prismResolverEndpoint: string): Castor

Defined in: src/castor/Castor.ts:52

Creates an instance of Castor as soon as a valid cryptographic interface is provided (Apollo).

Parameters

Parameter	Type	Default value	Description
apollo	Apollo	undefined
extraResolvers	ExtraResolver[]	[]
prismResolverEndpoint	string	"https://raw.githubusercontent.com/FabioPinheiro/prism-vdr/refs/heads/main/mainnet/diddoc/"	-

Returns

Castor

Methods

createPeerDID()

createPeerDID(publicKeys: PublicKey[], services: Service[]): Promise<DID>

Defined in: src/castor/Castor.ts:241

Creates a DID for a peer (a device or server that acts as a DID subject) using given key agreement and authentication key pairs and a list of services.

Parameters

Parameter	Type	Description
publicKeys	PublicKey[]
services	Service[]

Returns

Promise<DID>

Example

This function creates new peer DID, using a given key agreement, authentication key pairs, and a list of services. It may throw an error if the key pairs or services are invalid.

const peerDid = await castor.createPeerDID(
    [keyPairFromCurveEd25519, keyPairFromCurveX25519],
    [exampleService]
);

Implementation of

Castor.createPeerDID

---

createPrismDID()

createPrismDID(key: PublicKey | KeyPair, services?: Service[], authenticationKeys?: (PublicKey | KeyPair)[], issuanceKeys?: (PublicKey | KeyPair)[]): Promise<DID>

Defined in: src/castor/Castor.ts:165

Creates a DID for a prism (a device or server that acts as a DID owner and controller) using a given master public key and list of services.

Parameters

Parameter	Type	Default value	Description
key	PublicKey | KeyPair	undefined
services?	Service[]	undefined
authenticationKeys?	(PublicKey | KeyPair)[]	[]
issuanceKeys?	(PublicKey | KeyPair)[]	[]

Returns

Promise<DID>

Example

This function creates a new prism DID, using a given master Public Key and a list of Services. The Public Key may be an individual Key or a KeyPair It may throw an error if the master Public Key or Services are invalid.

const exampleServiceEndpoint = new Domain.DIDDocument.Service("didcomm", ["DIDCommMessaging"], {
 uri: "https://example.com/endpoint",
 accept: ["didcomm/v2"],
 routingKeys: ["did:example:somemediator#somekey"],
});
const prismDid = await castor.createPrismDID(
 keyPairFromCurveSecp256K1.publicKey,
 [exampleServiceEndpoint]
);

Implementation of

Castor.createPrismDID

---

createPrismDIDAtalaObject()

createPrismDIDAtalaObject(key: PrivateKey, did: DID): Promise<Uint8Array<ArrayBufferLike>>

Defined in: src/castor/Castor.ts:90

Creates a Prism DID Atala Object, a buffer contained the prism did create operation.

Parameters

Parameter	Type	Description
key	PrivateKey
did	DID

Returns

Promise<Uint8Array<ArrayBufferLike>>

---

getEcnumbasis()

getEcnumbasis(did: DID, publicKey: PublicKey): string

Defined in: src/castor/Castor.ts:445

Returns ecnumbasis from a valid DID and its related publicKey

Parameters

Parameter	Type	Description
did	DID
publicKey	PublicKey

Returns

string

Implementation of

Castor.getEcnumbasis

---

parseDID()

parseDID(did: string): DID

Defined in: src/castor/Castor.ts:80

Parses a string representation of a Decentralized Identifier (DID) into a DID object.

Parameters

Parameter	Type	Description
did	string

Returns

DID

Example

This function takes a string representation of a DID and returns an instance of Domain.DID. It may throw an error if the string is not a valid DID.

const parsedPrismDid = castor.parseDID(
 "did:prism:b6c0c33d701ac1b9a262a14454d1bbde3d127d697a76950963c5fd930605:Cj8KPRI7CgdtYXN0ZXIwEAFKLgoJc2VmsxEiECSTjyV7sUfCr_ArpN9rvCwR9fRMAhcsr_S7ZRiJk4p5k"
);

Implementation of

Castor.parseDID

---

resolveDID()

resolveDID(didstr: string | DID): Promise<DIDDocument>

Defined in: src/castor/Castor.ts:266

Asynchronously resolves a DID to its corresponding DID Document. This function may throw an error if the DID is invalid or the document cannot be retrieved. Note: only prism and peer DID methods are currently supported!

Parameters

Parameter	Type	Description
didstr	string | DID

Returns

Promise<DIDDocument>

Example

This function asynchronously resolves a DID to its corresponding DID Document. It may throw an error if the DID is invalid or the document is unretrievable.

const didDocument = await castor.resolveDID("did:prism:123456")

Implementation of

Castor.resolveDID

---

verifySignature()

verifySignature(did: DID, challenge: Uint8Array, signature: Uint8Array): Promise<boolean>

Defined in: src/castor/Castor.ts:336

Verifies the authenticity of a signature using the corresponding DID Document, challenge, and signature data. This function returns a boolean value indicating whether the signature is valid or not. This function may throw an error if the DID Document or signature data are invalid.

Parameters

Parameter	Type	Description
did	DID
challenge	Uint8Array
signature	Uint8Array

Returns

Promise<boolean>

Example

This function verifies the authenticity of a signature using given DID, challenge, and signature data. It returns a boolean value indicating whether the signature is valid or not. It may throw an error if the DID or signature data are invalid.

const message = "data to sign";
const messageBytes = new TextEncoder().encode(message);
const {mnemonics, seed} = apollo.createRandomSeed();
const privateKey = apollo.createPublicKey({
  type: KeyTypes.EC,
  curve: Curve.SECP256K1,
  seed: Buffer.from(seed.value).toString("hex"),
  derivationPath: "m/0'/0'/0'"
});
if (privateKey.isSignable()) {
  const signature = privateKey.sign(message);
  const did = castor.parseDID("did:prism:123456");
  const challenge = messageBytes
  const isValid = castor.verifySignature(
      castor.parseDID("did:prism:123456"),
      challenge, // Uint8Array
      signature // Uint8Array
  );
}

Implementation of

Castor.verifySignature