Alloy Book

Signers vs Ethereum Wallet

Signers implement the Signer trait which enables them to sign hashes, messages and typed data.

Alloy provides access to various signers out of the box such as PrivateKeySigner, AwsSigner, LedgerSigner etc.

These signers can directly be passed to a Provider using the ProviderBuilder. These signers are housed in the WalletFiller, which is responsible for signing transactions in the provider stack.

For example:

let signer: PrivateKeySigner = "0x...".parse()?;

let provider = ProviderBuilder::new()
    .wallet(signer)
    .connect_http("http://localhost:8545")?;

EthereumWallet is a type that can hold multiple different signers such PrivateKeySigner, AwsSigner, LedgerSigner etc and also be passed to the Provider using the ProviderBuilder.

The signer that instantiates EthereumWallet is set as the default signer. This signer is used to sign [TransactionRequest] and [TypedTransaction] objects that do not specify a signer address in the from field.

For example:

let ledger_signer = LedgerSigner::new(HDPath::LedgerLive(0), Some(1)).await?;
let aws_signer = AwsSigner::new(client, key_id, Some(1)).await?;
let pk_signer: PrivateKeySigner = "0x...".parse()?;

let mut wallet = EthereumWallet::from(pk_signer) // pk_signer will be registered as the default signer.
    .register_signer(aws_signer)
    .register_signer(ledger_signer);

let provider = ProviderBuilder::new()
    .wallet(wallet)
    .connect_http("http://localhost:8545")?;

The PrivateKeySigner will set to the default signer if the from field is not specified. One can hint the WalletFiller which signer to use by setting its corresponding address in the from field of the TransactionRequest.

If you wish to change the default signer after instantiating EthereumWallet, you can do so by using the register_default_signer method.

let mut wallet = EthereumWallet::from(pk_signer) // pk_signer will be registered as the default signer.
    .register_signer(ledger_signer);

wallet.register_default_signer(aws_signer);