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

🔹 Index

1. How it works
2. Initialisation
3. Use Cases
   • Get Address
   • Sign Transaction
   • Sign 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 {
    context = applicationContext // required on Android
    deviceManagementKit = dmk
    originToken = "your-origin-token"
}

You can also customize the Context Module endpoints:

val signerEth = ethereumSigner {
    context = applicationContext
    deviceManagementKit = dmk
    originToken = "your-origin-token"
    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 3 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,
        isHexadecimalValue = true,
    ),
)

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	Must be true for transaction signing

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 Message

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

val flow: Flow<DeviceActionResult<Signature>> = signerEth.signMessage(
    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
)