Internet Computer Signer Kit

This module provides the implementation of the Ledger Internet Computer (ICP) signer of the Device Management Kit. It enables interaction with the Internet Computer application on a Ledger device including:

Retrieving the ICP public key, account identifier and principal for a given derivation path
Signing an Internet Computer transaction
Signing an update call together with its read-state request (neuron management)
Querying the device app configuration and version

🔹 How it works

The Ledger Internet Computer Signer utilizes the advanced capabilities of the Ledger device to provide secure operations for end users. It takes advantage of the interface provided by the Device Management Kit to establish communication with the Ledger device and execute various operations. The communication with the Ledger device is performed using APDU s (Application Protocol Data Units), which are encapsulated within the Command object. These commands are then organized into tasks, allowing for the execution of complex operations with one or more APDUs. The tasks are further encapsulated within DeviceAction objects to handle different real-world scenarios. Finally, the Signer exposes dedicated and independent use cases that can be directly utilized by end users.

🔹 Installation

Note: This module is not standalone; it depends on the @ledgerhq/device-management-kit package, so you need to install it first.

To install the device-signer-kit-icp package, run the following command:


npm install @ledgerhq/device-signer-kit-icp

🔹 Initialisation

To initialise an ICP signer instance, you need a Ledger Device Management Kit instance and the ID of the session of the connected device. Use the SignerIcpBuilder:


const signerIcp = new SignerIcpBuilder({ dmk, sessionId }).build();

🔹 Use Cases

The SignerIcpBuilder.build() method will return a SignerIcp instance that exposes 4 dedicated methods, each of which calls an independent use case. Each use case will return an object that contains an observable and a method called cancel.

Use Case 1: Get Address

This method allows users to retrieve the ICP public key, account identifier and principal based on a given derivationPath.


const { observable, cancel } = signerIcp.getAddress(derivationPath, options);

Parameters

derivationPath
- Required
- Type: string (e.g., "44'/223'/0'/0/0")
- The derivation path used for the ICP address. See here for more information.
options
- Optional
- Type: AddressOptions
```
type AddressOptions = {
  checkOnDevice?: boolean;
  skipOpenApp?: boolean;
};
```
- checkOnDevice: An optional boolean indicating whether user confirmation on the device is required (true) or not (false).
- skipOpenApp: An optional boolean indicating whether to skip opening the ICP app on the device (true) or not (false). Use when the app is already open.

Returns

observable Emits DeviceActionState updates, including the following details:


type Address = {
  publicKey: string; // hex-encoded secp256k1 public key
  accountId: string; // hex-encoded account identifier
  principal: string; // textual principal
};

cancel A function to cancel the action on the Ledger device.

Use Case 2: Sign Transaction

Securely sign an Internet Computer transaction on Ledger devices.


const { observable, cancel } = signerIcp.signTransaction(
  derivationPath,
  transaction,
  options,
);

Parameters

derivationPath
- Required
- Type: string (e.g., "44'/223'/0'/0/0")
- The derivation path used for the ICP address.
transaction
- Required
- Type: Uint8Array
- The serialized transaction bytes (CBOR request) to sign.
options
- Optional
- Type: TransactionOptions
```
type TransactionOptions = {
  skipOpenApp?: boolean;
  stake?: boolean;
};
```
- skipOpenApp: An optional boolean indicating whether to skip opening the ICP app on the device (true) or not (false). Use when the app is already open.
- stake: An optional boolean. When true, signs a neuron-creation transfer (a governance-subaccount transfer) instead of a plain transfer. Defaults to false.

Returns

observable Emits DeviceActionState updates, including the following details:


type Signature = {
  r: string; // hex-encoded 32-byte R value
  s: string; // hex-encoded 32-byte S value
  v: number; // recovery id
  der: string; // hex-encoded DER signature
};

cancel A function to cancel the action on the Ledger device.

Use Case 3: Sign Update Call

Sign an Internet Computer update call together with its companion read-state request. Most neuron-management operations (dissolve, follow, split, hot-keys, maturity, …) are update calls to the NNS governance canister signed this way.


const { observable, cancel } = signerIcp.signUpdateCall(
  derivationPath,
  callRequest,
  readStateRequest,
  options,
);

Parameters

derivationPath
- Required
- Type: string (e.g., "44'/223'/0'/0/0")
- The derivation path used for the ICP address.
callRequest
- Required
- Type: Uint8Array
- The serialized update-call request bytes (CBOR envelope) to sign.
readStateRequest
- Required
- Type: Uint8Array
- The serialized read-state request bytes (CBOR envelope) signed alongside the call, used afterwards to poll the call’s status.
options
- Optional
- Type: CommonOptions
```
type CommonOptions = {
  skipOpenApp?: boolean;
};
```
- skipOpenApp: An optional boolean indicating whether to skip opening the ICP app on the device (true) or not (false). Use when the app is already open.

Returns

observable Emits DeviceActionState updates, including the following details:


type UpdateCallSignature = {
  requestHash: string; // hex-encoded signed request digest
  requestSignature: { r: string; s: string }; // hex-encoded r‖s over the call
  readStateHash: string; // hex-encoded signed read-state digest
  readStateSignature: { r: string; s: string }; // hex-encoded r‖s over the read-state
  readStateBody: Uint8Array; // the read-state request that was signed
};

cancel A function to cancel the action on the Ledger device.

Use Case 4: Get App Configuration

This method allows the user to fetch the current app configuration.


const { observable, cancel } = signerIcp.getAppConfiguration();

Parameters

None.

Returns

observable Emits DeviceActionState updates, including the following details:


type Version = {
  version: string; // "major.minor.patch"
  testMode: boolean;
  locked: boolean;
};

cancel A function to cancel the action on the Ledger device.

🔹 Observable Behavior

Each method returns an Observable emitting updates structured as DeviceActionState. These updates reflect the operation’s progress and status:

NotStarted: The operation hasn’t started.
Pending: The operation is in progress and may require user interaction.
Stopped: The operation was canceled or stopped.
Completed: The operation completed successfully, with results available.
Error: An error occurred.

Example Observable Subscription:


observable.subscribe({
  next: (state: DeviceActionState) => {
    switch (state.status) {
      case DeviceActionStatus.NotStarted: {
        console.log("The action is not started yet.");
        break;
      }
      case DeviceActionStatus.Pending: {
        const { intermediateValue } = state;
        console.log(
          "The action is pending and the intermediate value is: ",
          intermediateValue,
        );
        break;
      }
      case DeviceActionStatus.Stopped: {
        console.log("The action has been stopped.");
        break;
      }
      case DeviceActionStatus.Completed: {
        const { output } = state;
        console.log("The action has been completed: ", output);
        break;
      }
      case DeviceActionStatus.Error: {
        const { error } = state;
        console.log("An error occurred during the action: ", error);
        break;
      }
    }
  },
});

Intermediate Values in Pending Status:

When the status is DeviceActionStatus.Pending, the state will include an intermediateValue object that provides useful information for interaction:


const { requiredUserInteraction } = intermediateValue;
 
switch (requiredUserInteraction) {
  case UserInteractionRequired.VerifyAddress: {
    console.log("User needs to verify the address displayed on the device.");
    break;
  }
  case UserInteractionRequired.SignTransaction: {
    console.log("User needs to sign the transaction displayed on the device.");
    break;
  }
  case UserInteractionRequired.ConfirmOpenApp: {
    console.log("The user needs to confirm on the device to open the app.");
    break;
  }
  case UserInteractionRequired.UnlockDevice: {
    console.log("The user needs to unlock the device.");
    break;
  }
  case UserInteractionRequired.None: {
    console.log("No user action needed.");
    break;
  }
  default:
    const uncaughtUserInteraction: never = requiredUserInteraction;
    console.error("Unhandled user interaction case:", uncaughtUserInteraction);
}

🔹 Example

We encourage you to explore the Internet Computer Signer by trying it out in our online sample application . Experience how it works and see its capabilities in action. Of course, you will need a Ledger device connected.