Signers

A Signer in ethers is an abstraction of an Ethereum Account, which can be used to sign messages and transactions and send signed transactions to the Ethereum Network to execute state changing operations.

The available operations depend largely on the sub-class used.

For example, a Signer from MetaMask can send transactions and sign messages but cannot sign a transaction (without broadcasting it).

The most common Signers you will encounter are:

Signer

The Signer class is abstract and cannot be directly instantiated.

Instead use one of the concrete sub-classes, such as the Wallet, VoidSigner or JsonRpcSigner.

signer.connect( provider ) Signer

Sub-classes must implement this, however they may simply throw an error if changing providers is not supported.

signer.getAddress( ) Promise< string< Address > >

Returns a Promise that resolves to the account address.

This is a Promise so that a Signer can be designed around an asynchronous source, such as hardware wallets.

Sub-classes must implement this.

Signer.isSigner( object ) boolean

Returns true if an only if object is a Signer.

Blockchain Methods

signer.getBalance( [ blockTag = "latest" ] ) Promise< BigNumber >

Returns the balance of this wallet at blockTag.

signer.getChainId( ) Promise< number >

Returns the chain ID this wallet is connected to.

signer.getGasPrice( ) Promise< BigNumber >

Returns the current gas price.

signer.getTransactionCount( [ blockTag = "latest" ] ) Promise< number >

Returns the number of transactions this account has ever sent. This is the value required to be included in transactions as the nonce.

signer.call( transactionRequest ) Promise< string< DataHexString > >

Returns the result of calling using the transactionRequest, with this account address being used as the from field.

signer.estimateGas( transactionRequest ) Promise< BigNumber >

Returns the result of estimating the cost to send the transactionRequest, with this account address being used as the from field.

signer.resolveName( ensName ) Promise< string< Address > >

Returns the address associated with the ensName.

Signing

signer.signMessage( message ) Promise< string< RawSignature > >

This returns a Promise which resolves to the Raw Signature of message.

Sub-classes must implement this, however they may throw if signing a message is not supported, such as in a Contract-based Wallet or Meta-Transaction-based Wallet.

Note

If message is a string, it is treated as a string and converted to its representation in UTF8 bytes.

If and only if a message is a Bytes will it be treated as binary data.

For example, the string "0x1234" is 6 characters long (and in this case 6 bytes long). This is not equivalent to the array [ 0x12, 0x34 ], which is 2 bytes long.

A common case is to sign a hash. In this case, if the hash is a string, it must be converted to an array first, using the arrayify utility function.

signer.signTransaction( transactionRequest ) Promise< string< DataHexString > >

Returns a Promise which resolves to the signed transaction of the transactionRequest. This method does not populate any missing fields.

Sub-classes must implement this, however they may throw if signing a transaction is not supported, which is common for security reasons in many clients.

signer.sendTransaction( transactionRequest ) Promise< TransactionResponse >

This method populates the transactionRequest with missing fields, using populateTransaction and returns a Promise which resolves to the transaction.

Sub-classes must implement this, however they may throw if sending a transaction is not supported, such as the VoidSigner or if the Wallet is offline and not connected to a Provider.

signer._signTypedData( domain , types , value ) Promise< string< RawSignature > >

Signs the typed data value with types data structure for domain using the EIP-712 specification.

Experimental feature (this method name will change)

This is still an experimental feature. If using it, please specify the exact version of ethers you are using (e.g. spcify "5.0.18", not "^5.0.18") as the method name will be renamed from _signTypedData to signTypedData once it has been used in the field a bit.

Typed Data Example
// All properties on a domain are optional const domain = { name: 'Ether Mail', version: '1', chainId: 1, verifyingContract: '0xCcCCccccCCCCcCCCCCCcCcCccCcCCCcCcccccccC' }; // The named list of all type definitions const types = { Person: [ { name: 'name', type: 'string' }, { name: 'wallet', type: 'address' } ], Mail: [ { name: 'from', type: 'Person' }, { name: 'to', type: 'Person' }, { name: 'contents', type: 'string' } ] }; // The data to sign const value = { from: { name: 'Cow', wallet: '0xCD2a3d9F938E13CD947Ec05AbC7FE734Df8DD826' }, to: { name: 'Bob', wallet: '0xbBbBBBBbbBBBbbbBbbBbbbbBBbBbbbbBbBbbBBbB' }, contents: 'Hello, Bob!' }; const signature = await signer._signTypedData(domain, types, value); // '0x463b9c9971d1a144507d2e905f4e98becd159139421a4bb8d3c9c2ed04eb401057dd0698d504fd6ca48829a3c8a7a98c1c961eae617096cb54264bbdd082e13d1c'

Sub-Classes

It is very important that all important properties of a Signer are immutable. Since Ethereum is very asynchronous and deals with critical data (such as ether and other potentially valuable crypto assets), keeping properties such as the provider and address static throughout the life-cycle of the Signer helps prevent serious issues and many other classes and libraries make this assumption.

A sub-class must extend Signer and must call super().

signer.checkTransaction( transactionRequest ) TransactionRequest

This is generally not required to be overridden, but may be needed to provide custom behaviour in sub-classes.

This should return a copy of the transactionRequest, with any properties needed by call, estimateGas and populateTransaction (which is used by sendTransaction). It should also throw an error if any unknown key is specified.

The default implementation checks only if valid TransactionRequest properties exist and adds from to the transaction if it does not exist.

If there is a from field it must be verified to be equal to the Signer's address.

signer.populateTransaction( transactionRequest ) Promise< TransactionRequest >

This is generally not required to be overridden, but may be needed to provide custom behaviour in sub-classes.

This should return a copy of transactionRequest, follow the same procedure as checkTransaction and fill in any properties required for sending a transaction. The result should have all promises resolved; if needed the resolveProperties utility function can be used for this.

The default implementation calls checkTransaction and resolves to if it is an ENS name, adds gasPrice, nonce, gasLimit and chainId based on the related operations on Signer.

Wallet inherits ExternallyOwnedAccount and Signer

The Wallet class inherits Signer and can sign transactions and messages using a private key as a standard Externally Owned Account (EOA).

new ethers.Wallet( privateKey [ , provider ] )

Create a new Wallet instance for privateKey and optionally connected to the provider.

ethers.Wallet.createRandom( [ options = {} ] ) Wallet

Returns a new Wallet with a random private key, generated from cryptographically secure entropy sources. If the current environment does not have a secure entropy source, an error is thrown.

Wallets created using this method will have a mnemonic.

ethers.Wallet.fromEncryptedJson( json , password [ , progress ] ) Promise< Wallet >

Create an instance from an encrypted JSON wallet.

If progress is provided it will be called during decryption with a value between 0 and 1 indicating the progress towards completion.

ethers.Wallet.fromEncryptedJsonSync( json , password ) Wallet

Create an instance from an encrypted JSON wallet.

This operation will operate synchronously which will lock up the user interface, possibly for a non-trivial duration. Most applications should use the asynchronous fromEncryptedJson instead.

ethers.Wallet.fromMnemonic( mnemonic [ , path , [ wordlist ] ] ) Wallet

Create an instance from a mnemonic phrase.

If path is not specified, the Ethereum default path is used (i.e. m/44'/60'/0'/0/0).

If wordlist is not specified, the English Wordlist is used.

Properties

wallet.address string< Address >

The address for the account this Wallet represents.

wallet.provider Provider

The provider this wallet is connected to, which will be used for any Blockchain Methods methods. This can be null.

Note

A Wallet instance is immutable, so if you wish to change the Provider, you may use the connect method to create a new instance connected to the desired provider.

wallet.publicKey string< DataHexString< 65 > >

The uncompressed public key for this Wallet represents.

Methods

wallet.encrypt( password , [ options = {} , [ progress ] ] ) Promise< string >

Encrypt the wallet using password returning a Promise which resolves to a JSON wallet.

If progress is provided it will be called during decryption with a value between 0 and 1 indicating the progress towards completion.

Wallet Examples
// Create a wallet instance from a mnemonic... mnemonic = "announce room limb pattern dry unit scale effort smooth jazz weasel alcohol" walletMnemonic = Wallet.fromMnemonic(mnemonic) // ...or from a private key walletPrivateKey = new Wallet(walletMnemonic.privateKey) walletMnemonic.address === walletPrivateKey.address // true // The address as a Promise per the Signer API walletMnemonic.getAddress() // { Promise: '0x71CB05EE1b1F506fF321Da3dac38f25c0c9ce6E1' } // A Wallet address is also available synchronously walletMnemonic.address // '0x71CB05EE1b1F506fF321Da3dac38f25c0c9ce6E1' // The internal cryptographic components walletMnemonic.privateKey // '0x1da6847600b0ee25e9ad9a52abbd786dd2502fa4005dd5af9310b7cc7a3b25db' walletMnemonic.publicKey // '0x04b9e72dfd423bcf95b3801ac93f4392be5ff22143f9980eb78b3a860c4843bfd04829ae61cdba4b3b1978ac5fc64f5cc2f4350e35a108a9c9a92a81200a60cd64' // The wallet mnemonic walletMnemonic.mnemonic // { // locale: 'en', // path: "m/44'/60'/0'/0/0", // phrase: 'announce room limb pattern dry unit scale effort smooth jazz weasel alcohol' // } // Note: A wallet created with a private key does not // have a mnemonic (the derivation prevents it) walletPrivateKey.mnemonic // null // Signing a message walletMnemonic.signMessage("Hello World") // { Promise: '0x14280e5885a19f60e536de50097e96e3738c7acae4e9e62d67272d794b8127d31c03d9cd59781d4ee31fb4e1b893bd9b020ec67dfa65cfb51e2bdadbb1de26d91c' } tx = { to: "0x8ba1f109551bD432803012645Ac136ddd64DBA72", value: utils.parseEther("1.0") } // Signing a transaction walletMnemonic.signTransaction(tx) // { Promise: '0xf865808080948ba1f109551bd432803012645ac136ddd64dba72880de0b6b3a7640000801ca0918e294306d177ab7bd664f5e141436563854ebe0a3e523b9690b4922bbb52b8a01181612cec9c431c4257a79b8c9f0c980a2c49bb5a0e6ac52949163eeb565dfc' } // The connect method returns a new instance of the // Wallet connected to a provider wallet = walletMnemonic.connect(provider) // Querying the network wallet.getBalance(); // { Promise: { BigNumber: "42" } } wallet.getTransactionCount(); // { Promise: 0 } // Sending ether wallet.sendTransaction(tx)

VoidSigner inherits Signer

A VoidSigner is a simple Signer which cannot sign.

It is useful as a read-only signer, when an API requires a Signer as a parameter, but it is known only read-only operations will be carried.

For example, the call operation will automatically have the provided address passed along during the execution.

new ethers.VoidSigner( address [ , provider ] ) VoidSigner

Create a new instance of a VoidSigner for address.

voidSigner.address string< Address >

The address of this VoidSigner.

VoidSigner Pre-flight Example
address = "0x8ba1f109551bD432803012645Ac136ddd64DBA72" signer = new ethers.VoidSigner(address, provider) // The DAI token contract abi = [ "function balanceOf(address) view returns (uint)", "function transfer(address, uint) returns (bool)" ] contract = new ethers.Contract("dai.tokens.ethers.eth", abi, signer) // Get the number of tokens for this account tokens = await contract.balanceOf(signer.getAddress()) // { BigNumber: "1023806475162018481030" } // // Pre-flight (check for revert) on DAI from the signer // // Note: We do not have the private key at this point, this // simply allows us to check what would happen if we // did. This can be useful to check before prompting // a request in the UI // // This will pass since the token balance is available contract.callStatic.transfer("donations.ethers.eth", tokens) // { Promise: true } // This will fail since it is greater than the token balance contract.callStatic.transfer("donations.ethers.eth", tokens.add(1)) // Error: call revert exception (method="transfer(address,uint256)", errorSignature="Error(string)", errorArgs=["Dai/insufficient-balance"], reason="Dai/insufficient-balance", code=CALL_EXCEPTION, version=abi/5.0.9)

ExternallyOwnedAccount

This is an interface which contains a minimal set of properties required for Externally Owned Accounts which can have certain operations performed, such as encoding as a JSON wallet.

eoa.address string< Address >

The Address of this EOA.

eoa.privateKey string< DataHexString< 32 > >

The privateKey of this EOA

eoa.mnemonic Mnemonic

Optional. The account HD mnemonic, if it has one and can be determined. Some sources do not encode the mnemonic, such as HD extended keys.