LACChain DID Method NodeJS Library

DID Specification | DID Registry Contracts

This library is an implementation of LACChain DID Method in NodeJS. It provides the necessary methods and functions to interact with a DID and resolve a DID Document without the need to directly call the smart contracts.

Pre-requisites

• NodeJS > 14.4

Usage

Just install the package from NPM repository.

npm install @lacchain/did

And import it in your NodeJS project.

import { DID, DIDRecoverable, Resolver } from '@lacchain/did'

• The DID(config={}) and DIDRecoverable(config={}) classes can be used to create and update a DID Document. Where config is an object that can have the following properties:

Name	Type	Required	Description
registry	String	true	The address of DID Registry
rpcUrl	String	true	The URL of Ethereum RPC API
network	String	true	The name of the network (ie: main, test)
address	String	false	The address of a DID. If this is set a read-only LACChainDID Object will be created unless you provide controllerPrivateKey property
controllerPrivateKey	String	false	The private key of the DID address. If you set the controller private key you must also provide the DID address

If you don't provide the address and controllerPrivateKey, the class will generate one automatically.

• The Resolver(config={}) class can be used to resolve a DID Document from the DID identifier.

  Where config is an object that can have the following properties:

Name	Type	Required	Description
networks	Array	true	An array of network config objects to use for resolving DID Document, where each item is an object with the following properties: - name: The network name - registry: The address of DID Registry - rpcUrl: The URL of Ethereum RPC API
mode	String	false	The resolving DID Document mechanism: explicit, implicit (default)

1. Create a new DID

Depending on the functionalities that you want to use, there are two types of classes to operate a DID

• Regular DID: It is the basic DID that allows multiple controllers and automatic key rotation.

const did = new DID( {
   registry: '0xbDa1238272FDA6888556449Cb77A87Fc8205E8ba',
   rpcUrl: 'https://writer.lacchain.net',
   network: 'main'
} );

• Recoverable DID: It is the advanced DID that allows, in addition to the functions of a basic DID, key recovery.

const did = new DIDRecoverable( {
   registry: '0xbDa1238272FDA6888556449Cb77A87Fc8205E8ba',
   rpcUrl: 'https://writer.lacchain.net',
   network: 'main'
} );

LAC-NET Gas Model

If you are planning to interact with the LACChain / LACNET Gas Model, just specify the nodeAddress & expiration parameters in the config object:

const did = new DID( {
   registry: '0xB9D96a0bDd52FE48fC504d0BB28AF51091275C81',
   rpcUrl: 'http://34.69.22.82',
   nodeAddress: '0xd00e6624a73f88b39f82ab34e8bf2b4d226fd768',
   expiration: 1736394529,
   network: 'main'
} );

Or,

const did = new DIDRecoverable( {
   registry: '0xB9D96a0bDd52FE48fC504d0BB28AF51091275C81',
   rpcUrl: 'http://34.69.22.82',
   nodeAddress: '0xd00e6624a73f88b39f82ab34e8bf2b4d226fd768',
   expiration: 1736394529,
   network: 'main'
} );

Note: Use the same parameters in the resolver class

The basic properties of a DID are:

console.log( did.id ); // did:lac:main:0x47adc0faa4f6eb42b499187317949ed99e77ee85
console.log( did.address ); // 0x47adc0faa4f6eb42b499187317949ed99e77ee85

2. Add / remove a new controller

Before change to another controller, it is necessarily to add it first by invoking the next function:

await did.addController( '0x4a5a6460d00c4d8c2835a3067f53fb42021d5bb9' );

It is also possible to remove an extra controller registered with two conditions:

1. The controller to remove cannot be the current controller
2. Must remain at least one controller

await did.removeController( '0x4a5a6460d00c4d8c2835a3067f53fb42021d5bb9' );

3. Change the current controller

Once the new controller has been registered, it can be changed by invoking the following function:

await did.changeController( '0x4a5a6460d00c4d8c2835a3067f53fb42021d5bb9' );

The current controller is the only one that has the permissions to execute changes on the DID (there can only be one current controller), that is why when changing the controller, it is necessary to specify to the DID class which is the controller's private key to that can continue to sign transactions to the network. To specify the private key of current controller, just call the next function:

await did.setControllerKey( PRIVATE_KEY_HEX );

Note: The private key must be in hex format without 0x prefix.

4. Get the current controller

To get the current active controller, just call:

const currentController = await did.getController(); // 0x4a5a6460d00c4d8c2835a3067f53fb42021d5bb9

5. Get all registered controllers

The function to get all the controllers registered for the DID will return an array of controllers addresses:

const controllers = await did.getController(); // ['0x47adc0faa4f6eb42b499187317949ed99e77ee85', '0x4a5a6460d00c4d8c2835a3067f53fb42021d5bb9']

6. Add a new Verification Method

According to the W3C specification, it is possible to add Verification Methods to a DID that have a general purpose, for this it is enough to invoke the following function:

await did.addVerificationMethod({
   type: 'vm',
   algorithm: 'esecp256k1rm',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER,
   expiration: 31536000 // default: 31536000
});

Where type can (according to the W3C DID Verification Relationships):

• vm: Generic Verification Method
• auth: Authentication Method
• asse: Assertion Method
• keya: Key Agreement
• dele: Delegation Capability
• invo: Invocation Capability

And algorithm can be (see W3C DID Verification Method Types):

• jwk: JsonWebKey2020,
• esecp256k1vk: EcdsaSecp256k1VerificationKey2019,
• esecp256k1rm: EcdsaSecp256k1RecoveryMethod2020,
• edd25519vk: Ed25519VerificationKey2018,
• gpgvk: GpgVerificationKey2020,
• rsavk: RsaVerificationKey2018,
• x25519ka: X25519KeyAgreementKey2019,
• ssecp256k1vk: SchnorrSecp256k1VerificationKey2019

And encoding support the following formats (according to the W3C DID Verification Method Properties):

• hex: Hexadecimal
• base64: Base 64
• base58: Base 58

The publicKey represents the Public Key itself in the encoding format specified.

And the controller must be the Public Key Controller (String), usually a DID. Can be even of other DID method.

The expiration is the expiration time (in seconds) ahead of current time. This field is optional, and the default expiration time is: 31536000

Verification Relationships

In order to facilitate the registration of Verification Methods according to the type of Relationship, it is possible to use specific functions for this purpose.

• To add an Authentication Method

await did.addAuthenticationMethod( {
   algorithm: 'esecp256k1rm',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

• To add an Assertion Method

await did.addAssertionMethod( {
   algorithm: 'esecp256k1rm',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

• To add a Key Agreement

await did.addKeyAgreement( {
   algorithm: 'x25519ka',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

• To add a Delegation Capability

await did.addCapabilityDelegation( {
   algorithm: 'edd25519vk',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

• To add an Invocation Capability

await did.addCapabilityInvocation( {
   algorithm: 'edd25519vk',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

5. Bind an existing Verification Method

It is also possible to have a Verification Method (VM) associated with more than one relationship, that is why once a VM is registered it is possible to bind it to a specific relationship using the VM id.

Depending on the relationship it is possible to bind a VM:

• To bind an Authentication Method

await did.bindAuthenticationMethod( VERIFICATION_METHOD_ID );

• To bind an Assertion Method

await did.bindAssertionMethod( VERIFICATION_METHOD_ID );

• To bind a Key Agreement

await did.bindKeyAgreement( VERIFICATION_METHOD_ID );

• To bind a Delegation Capability

await did.bindCapabilityDelegation( VERIFICATION_METHOD_ID );

• To bind an Invocation Capability

await did.bindCapabilityInvocation( VERIFICATION_METHOD_ID );

6. Revoke a Verification Method

All VMs have an expiration time, however, it is possible to revoke them early using the following function:

await did.revokeVerificationMethod( {
   type: 'vm',
   algorithm: 'esecp256k1rm',
   encoding: 'hex',
   publicKey: PUBLIC_KEY_HEX,
   controller: PUBLIC_KEY_CONTROLLER
} );

It is important to provide all properties of the VM to revoke (except the expiration time), that is because they conform the key of the VM.

7. Add a Service

To add a Service to the DID, just provide the type and endpoint fields as Strings.

await did.addService( {
   type: 'mailbox',
   endpoint: 'https://mailbox.lacchain.net'
} );

9. Enable / Disable Automatic Key Rotation

To enable Automatic Key Rotation functionality, it is necessarily to comply with the following condition:

• Add at least el minimum number of controllers specified in the DID Registry
• The key rotation time (in seconds) must be greater or equal that the minimum rotation time specified in the DID Registry

await did.enableKeyRotation( ROTATION_TIME_SECONDS );

To disable this functionality, just call:

await did.disableKeyRotation();

10. Recover the DID control

This functionality will only be available if the DIDRecoverable class is instantiated and also the registry points to the Smart Contract that supports it.

await did.recover( CONTROLLER_ADDRESS, CONTROLLER_PRIVATE_KEY );

Where:

• CONTROLLER_ADDRESS: The controller address that you will prove ownership (Needs to be previously registered in the DID)
• CONTROLLER_PRIVATE_KEY: Is the controller private key that you will prove ownership (in hex format without 0x prefix)

Note: The recover function needs to be called n/2 + 1 times.

Testing

The unit test will be performed in the LACChain Main Network. If you want to change that, edit directly the files in the /test directory

$ npm install
$ npm test