Use the Ethereum Signer

This module provides the implementation of the Ledger Ethereum Signer for the Mobile Device Management Kit. It enables interaction with the Ethereum application on a Ledger device:

Retrieving the Ethereum address using a given derivation path
Signing an Ethereum transaction (Clear Signing )
Signing a message displayed on a Ledger device
Signing an EIP-712 typed data message

🔹 How it works

The Ledger Ethereum Signer uses the interface provided by the Device Management Kit to establish communication with the Ledger device and execute operations. Communication is performed using APDUs , encapsulated within Command objects, which are in turn encapsulated within DeviceAction objects to handle real-world scenarios.

For transaction signing, the Signer integrates with the Context Module to provide context data to the device, enabling Clear Signing — the display of human-readable transaction details on the device screen.

🔹 Initialisation

To initialize an Ethereum signer instance, you need a DeviceManagementKitApi instance. Use the ethereumSigner builder DSL:


import com.ledger.signer.eth.ethereumSigner
 
val signerEth = ethereumSigner(
    deviceManagementKit = dmk,
    originToken = "your-origin-token",
) {
    context = applicationContext // required on Android
}

ℹ️

The originToken is required by the default Context Module for transaction checks. It should be delivered by Ledger — without it, Transaction Checks will not be available.

You can also customize the Context Module endpoints:


val signerEth = ethereumSigner(
    deviceManagementKit = dmk,
    originToken = "your-origin-token",
) {
    context = applicationContext
    calUrl = "https://your-custom-cal-url"
    metadataServiceUrl = "https://your-custom-metadata-url"
    transactionCheckUrl = "https://your-custom-tx-check-url"
    enableLog = true
}

🔹 Use Cases

The EthereumSigner exposes 4 dedicated methods. Each returns a Flow<DeviceActionResult<T>> — a stream of state updates tracking the operation’s progress.

Use Case 1: Get Address

Retrieve the Ethereum address for a given derivation path.


val flow: Flow<DeviceActionResult<EthereumAddress>> = signerEth.getAddress(
    deviceUid = connectedDevice.uid,
    request = GetEthereumAddressRequest(
        derivationPath = "44'/60'/0'/0/0",
        checkOnDevice = false,
        withChainCode = false,
    ),
)

Parameters

deviceUid
- Required
- Type: String
- The UID of the connected device, from ConnectedDevice.uid.

request

Required
Type: GetEthereumAddressRequest

Field	Type	Description
`derivationPath`	`String`	Derivation path, e.g. `"44'/60'/0'/0/0"`
`checkOnDevice`	`Boolean`	Whether user confirmation is required on the device
`withChainCode`	`Boolean`	Whether to return the chain code

Returns

Flow<DeviceActionResult<EthereumAddress>>


data class EthereumAddress(
    val publicKey: String,   // Public key derived from the given path
    val address: String,     // Ethereum address (hex format)
    val chainCode: String?,  // Chain code (if requested)
)

Use Case 2: Sign Transaction

Sign an Ethereum transaction using Clear Signing on the Ledger device. The Context Module automatically enriches the transaction with token, NFT, and trusted name information so the device can display human-readable details.


val flow: Flow<DeviceActionResult<Signature>> = signerEth.signTransaction(
    deviceUid = connectedDevice.uid,
    request = SignEthereumRequest(
        derivationPath = "44'/60'/0'/0/0",
        value = rawTransactionHex,
    ),
)

A transaction that already carries a signature is accepted: the signature is dropped and the transaction is signed again.

Parameters

deviceUid
- Required
- Type: String
- The UID of the connected device.
request
- Required
- Type: SignEthereumRequest
Field Type Description
derivationPath String Derivation path, e.g. "44'/60'/0'/0/0"
value String RLP-encoded transaction as hex string
isHexadecimalValue Boolean Ignored for transaction signing (default false)

Returns

Flow<DeviceActionResult<Signature>>


data class Signature(
    val r: String,  // R component of the ECDSA signature (hex)
    val s: String,  // S component of the ECDSA signature (hex)
    val v: Int,     // Recovery parameter
)

Use Case 3: Sign Personal Message

Sign a text message (EIP-191 personal_sign) displayed on the Ledger device.


val flow: Flow<DeviceActionResult<Signature>> = signerEth.signPersonalMessage(
    deviceUid = connectedDevice.uid,
    request = SignEthereumRequest(
        derivationPath = "44'/60'/0'/0/0",
        value = "Hello from Ledger",
        isHexadecimalValue = false,
    ),
)

Parameters

deviceUid
- Required
- Type: String
- The UID of the connected device.
request
- Required
- Type: SignEthereumRequest
Field Type Description
derivationPath String Derivation path, e.g. "44'/60'/0'/0/0"
value String Message to sign (UTF-8 string or hex)
isHexadecimalValue Boolean Set to true if value is hexadecimal

Returns

Flow<DeviceActionResult<Signature>>


data class Signature(
    val r: String,  // R component of the ECDSA signature (hex)
    val s: String,  // S component of the ECDSA signature (hex)
    val v: Int,     // Recovery parameter
)

Use Case 4: Sign Typed Data

Sign an EIP-712 typed data message. The Context Module provides the data needed to display the fields in a readable way on the device.


val flow: Flow<DeviceActionResult<Signature>> = signerEth.signEip712Message(
    deviceUid = connectedDevice.uid,
    request = SignEthereumRequest(
        derivationPath = "44'/60'/0'/0/0",
        value = typedDataJson,
    ),
)

Parameters

deviceUid
- Required
- Type: String
- The UID of the connected device.
request
- Required
- Type: SignEthereumRequest
Field Type Description
derivationPath String Derivation path, e.g. "44'/60'/0'/0/0"
value String EIP-712 typed data (domain, types, message) as a JSON string

Returns

Flow<DeviceActionResult<Signature>>


data class Signature(
    val r: String,  // R component of the ECDSA signature (hex)
    val s: String,  // S component of the ECDSA signature (hex)
    val v: Int,     // Recovery parameter
)

🔹 Errors

When the user rejects an operation on the device, the failure reason is EthereumErrors.CancelByUser. The other Ethereum application errors are listed in EthereumErrors.

🔹 Lifecycle

The EthereumSigner is initialized once per process and must be initialized before use. Building a second instance throws EthereumSigner already initialized, and there is no public destroy or reset API: treat the signer as a process-wide singleton.