Ethers.Signer behaviour (Ethers v0.7.0)

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Signer behaviour.

A signer module is (at least) capable of signing transactions and listing accounts in the signer.

Builtin Signers

Ethers ships with some default signers that you can use.

  • Ethers.Signer.JsonRPC: Can be used with most wallets, geth, web3signer or any other platform which exposes a JsonRPC endpoint and implements eth_signTransaction and eth_accounts functions.
  • Ethers.Signer.Local: This signs transactions locally but is highly discouraged to use in a production environment as it does not have any security measures built in.

Custom Signers

Custom signers can also be implemented which must adhere to this behvaviour.

For signing transactions in custom signers the functions in Ethers.Transaction module might become handy. Check out the source code of built in signers for in depth info.

A signer may also implement the optional sign_typed_data/2 callback to support signing EIP-712 typed structured data (see Ethers.TypedData) and the optional personal_sign/2 callback to support signing EIP-191 personal messages (see Ethers.PersonalMessage). Signers that do not implement them will simply not support those signing schemes.

Globally Default Signer

If desired, a signer can be configured to be used for all operations in Ethers using elixir config.

config :ethers,
  default_signer: Ethers.Signer.JsonRPC,
  default_signer_opts: [url: "..."]

Summary

Callbacks

accounts(opts)

Returns the available signer account addresses.

personal_sign(message, opts)

Signs an EIP-191 personal message and returns the signature.

sign_transaction(tx, opts)

Signs a binary and returns the signature

sign_typed_data(typed_data, opts)

Signs an EIP-712 typed-data payload and returns the signature.

Callbacks

accounts(opts)

@callback accounts(opts :: Keyword.t()) ::
  {:ok, [Ethers.Types.t_address()]}
  | {:error, reason :: :not_supported | term()}

Returns the available signer account addresses.

This method might not be supported by all signers. If a signer does not support this function it should return {:error, :not_supported}.

Parameters

  • opts: Other options passed to the signer as signer_opts

personal_sign(message, opts)

(optional) 
@callback personal_sign(message :: binary(), opts :: Keyword.t()) ::
  {:ok, binary()} | {:error, reason :: term()}

Signs an EIP-191 personal message and returns the signature.

This is an optional callback. Signers that do not implement it do not support personal message signing.

Parameters

  • message: The message to sign, as raw bytes. (See Ethers.PersonalMessage)
  • opts: Other options passed to the signer as signer_opts.

Returns {:ok, signature} where signature is a 0x-prefixed 65-byte signature hex string.

sign_transaction(tx, opts)

@callback sign_transaction(
  tx :: Ethers.Transaction.t_payload(),
  opts :: Keyword.t()
) :: {:ok, encoded_signed_transaction :: binary()} | {:error, reason :: term()}

Signs a binary and returns the signature

Parameters

  • tx: The transaction object. (An Ethers.Transaction struct)
  • opts: Other options passed to the signer as signer_opts.

sign_typed_data(typed_data, opts)

(optional) 
@callback sign_typed_data(typed_data :: Ethers.TypedData.t(), opts :: Keyword.t()) ::
  {:ok, binary()} | {:error, reason :: term()}

Signs an EIP-712 typed-data payload and returns the signature.

This is an optional callback. Signers that do not implement it do not support typed-data signing.

Parameters

  • typed_data: The typed-data payload to sign. (An Ethers.TypedData struct)
  • opts: Other options passed to the signer as signer_opts.

Returns {:ok, signature} where signature is a 0x-prefixed 65-byte signature hex string.