# `Ethers.Signer`
[🔗](https://github.com/ExWeb3/elixir_ethers/blob/v0.6.12/lib/ethers/signer.ex#L1)

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.

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

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

# `accounts`

```elixir
@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`

# `sign_transaction`

```elixir
@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`.

---

*Consult [api-reference.md](api-reference.md) for complete listing*