_section: 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: - [[Wallet]], which is a class which knows its private key and can execute any operations with it - [[JsonRpcSigner]], which is connected to a [[JsonRpcProvider]] (or sub-class) and is acquired using [getSigner](JsonRpcProvider-getSigner) _subsection: Signer @ @SRC 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]]. _property: signer.connect(provider) => [[Signer]] @ Sub-classes **must** implement this, however they may simply throw an error if changing providers is not supported. _property: signer.getAddress() => Promise> @ @SRC 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. _property: Signer.isSigner(object) => boolean @ @SRC Returns true if and only if //object// is a **Signer**. _heading: Blockchain Methods @ _property: signer.getBalance([ blockTag = "latest" ]) => Promise<[[BigNumber]]> @ @SRC Returns the balance of this wallet at //blockTag//. _property: signer.getChainId() => Promise @ @SRC Returns the chain ID this wallet is connected to. _property: signer.getGasPrice() => Promise<[[BigNumber]]> @ @SRC Returns the current gas price. _property: signer.getTransactionCount([ blockTag = "latest" ]) => Promise @ @SRC Returns the number of transactions this account has ever sent. This is the value required to be included in transactions as the ``nonce``. _property: signer.call(transactionRequest) => Promise> @ @SRC Returns the result of calling using the //transactionRequest//, with this account address being used as the ``from`` field. _property: signer.estimateGas(transactionRequest) => Promise<[[BigNumber]]> @ @SRC Returns the result of estimating the cost to send the //transactionRequest//, with this account address being used as the ``from`` field. _property: signer.resolveName(ensName) => Promise> @ @SRC Returns the address associated with the //ensName//. _heading: Signing @ _property: signer.signMessage(message) => Promise> @ This returns a Promise which resolves to the [[signature-raw]] of //message//. A signed message is prefixd with ``"\\x19Ethereum signed message:\\n"`` and the length of the message, using the [hashMessage](utils-hashMessage) method, so that it is [EIP-191](link-eip-191) compliant. If recovering the address in Solidity, this prefix will be required to create a matching hash. 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: 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](utils-arrayify) utility function. _null: _property: signer.signTransaction(transactionRequest) => Promise> @ 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. _property: signer.sendTransaction(transactionRequest) => Promise<[[providers-TransactionResponse]]> @ This method populates the transactionRequest with missing fields, using [populateTransaction](Signer-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]]. _property: signer._signTypedData(domain, types, value) => Promise> @ Signs the typed data //value// with //types// data structure for //domain// using the [[link-eip-712]] specification. _warning: 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. _code: Typed Data Example @lang //_hide: signer = new Wallet("0x1234567890123456789012345678901234567890123456789012345678901234"); // 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!' }; //_result: signature = await signer._signTypedData(domain, types, value); //_log: _heading: 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()``. _property: signer.checkTransaction(transactionRequest) => [[providers-TransactionRequest]] @ @SRC 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 [[providers-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. _property: signer.populateTransaction(transactionRequest) => Promise<[[providers-TransactionRequest]]> @ @SRC 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](utils-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. _subsection: Wallet @ @INHERIT<[[ExternallyOwnedAccount]] and [[Signer]]> @SRC The Wallet class inherits [[Signer]] and can sign transactions and messages using a private key as a standard Externally Owned Account (EOA). _property: new ethers.Wallet(privateKey [ , provider ]) @ @SRC Create a new Wallet instance for //privateKey// and optionally connected to the //provider//. _property: ethers.Wallet.createRandom( [ options = { } ]) => [[Wallet]] @ @SRC 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. _property: ethers.Wallet.fromEncryptedJson(json, password [ , progress ]) => Promise<[[Wallet]]> @ @SRC 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. _property: ethers.Wallet.fromEncryptedJsonSync(json, password) => [[Wallet]] @ @SRC 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. _property: 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. _heading: Properties @ _property: wallet.address => string<[[address]]> The address for the account this Wallet represents. _property: wallet.provider => [[Provider]] The provider this wallet is connected to, which will be used for any [[Signer--blockchain-methods]] methods. This can be null. _note: Note A **Wallet** instance is immutable, so if you wish to change the Provider, you may use the [connect](Signer-connect) method to create a new instance connected to the desired provider. _property: wallet.publicKey => string<[[DataHexString]]<65>> The uncompressed public key for this Wallet represents. _heading: Methods @ _property: wallet.encrypt(password, [ options = { }, [ progress ] ]) => Promise @ 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. _code: Wallet Examples @lang // 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) //_result: walletMnemonic.address === walletPrivateKey.address //_log: // The address as a Promise per the Signer API //_result: await walletMnemonic.getAddress() //_log: // A Wallet address is also available synchronously //_result: walletMnemonic.address //_log: // The internal cryptographic components //_result: walletMnemonic.privateKey //_log: //_result: walletMnemonic.publicKey //_log: // The wallet mnemonic //_result: walletMnemonic.mnemonic //_log: // Note: A wallet created with a private key does not // have a mnemonic (the derivation prevents it) //_result: walletPrivateKey.mnemonic //_log: // Signing a message //_result: await walletMnemonic.signMessage("Hello World") //_log: tx = { to: "0x8ba1f109551bD432803012645Ac136ddd64DBA72", value: utils.parseEther("1.0") } // Signing a transaction //_result: await walletMnemonic.signTransaction(tx) //_log: // The connect method returns a new instance of the // Wallet connected to a provider //_result: wallet = walletMnemonic.connect(provider) //_null: // Querying the network //_result: await wallet.getBalance(); //_log: //_result: await wallet.getTransactionCount(); //_log: // Sending ether //_hide: wallet = localSigner; /* prevent insufficient funds error from blowing up the docs */ //_result: await wallet.sendTransaction(tx) //_log: _subsection: VoidSigner @ @INHERIT<[[Signer]]> @SRC 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. _property: new ethers.VoidSigner(address [ , provider ]) => [[VoidSigner]] Create a new instance of a **VoidSigner** for //address//. _property: voidSigner.address => string<[[address]]> The address of this **VoidSigner**. _code: VoidSigner Pre-flight Example @lang 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 //_result: tokens = await contract.balanceOf(signer.getAddress()) //_log: // // 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 //_result: await contract.callStatic.transfer("donations.ethers.eth", tokens) //_log: // This will fail since it is greater than the token balance //_throws: await contract.callStatic.transfer("donations.ethers.eth", tokens.add(1)) //_log: _subsection: 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. _property: eoa.address => string<[[address]]> The [[address]] of this EOA. _property: eoa.privateKey => string<[[DataHexString]]<32>> The privateKey of this EOA _property: 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.