# `CCXT.WS.Auth.Behaviour`
[🔗](https://github.com/ZenHive/ccxt_client/blob/main/lib/ccxt/ws/auth/behaviour.ex#L1)

Behaviour for WebSocket authentication pattern implementations.

All WS auth patterns implement callbacks for building auth messages
and handling auth responses. Patterns reuse `CCXT.Signing` crypto
primitives (`hmac_sha256/2`, `hmac_sha384/2`, `hmac_sha512/2`,
`encode_hex/1`, `encode_base64/1`, `timestamp_ms/0`, etc.).

## Auth Flow

1. Caller invokes `CCXT.WS.Auth.pre_auth/4` (REST round-trip when needed)
2. Caller invokes `CCXT.WS.Auth.build_auth_message/4`
3. Caller sends the returned frame via `ZenWebsocket.Client.send_message/2`
4. Caller feeds the response back through `CCXT.WS.Auth.handle_auth_response/3`

## Pattern Types

- **Direct HMAC** — sign payload, send auth message (bybit, okx, bitfinex, …)
- **Pre-auth** — REST call first, then WS (binance `listen_key`, kraken `rest_token`)
- **Inline** — auth included in each subscribe message (coinbase)

## Implementing a Pattern

    defmodule CCXT.WS.Auth.DirectHmacExpiry do
      @behaviour CCXT.WS.Auth.Behaviour

      @impl true
      def pre_auth(_credentials, _config, _opts), do: {:ok, %{}}

      @impl true
      def build_auth_message(credentials, config, opts) do
        {:ok, %{"op" => "auth", "args" => [api_key, expires, signature]}}
      end

      @impl true
      def handle_auth_response(response, _state) do
        if response["success"], do: :ok, else: {:error, :auth_failed}
      end
    end

# `auth_config`

```elixir
@type auth_config() :: map()
```

# `auth_message`

```elixir
@type auth_message() :: map()
```

# `auth_response`

```elixir
@type auth_response() :: map()
```

# `auth_state`

```elixir
@type auth_state() :: map()
```

# `build_result`

```elixir
@type build_result() :: {:ok, auth_message()} | :no_message | {:error, term()}
```

# `handle_result`

```elixir
@type handle_result() :: :ok | {:ok, map()} | {:error, term()}
```

# `opts`

```elixir
@type opts() :: keyword()
```

# `pre_auth_result`

```elixir
@type pre_auth_result() :: {:ok, map()} | {:error, term()}
```

# `build_auth_message`

```elixir
@callback build_auth_message(
  credentials :: CCXT.Credentials.t(),
  config :: auth_config(),
  opts :: opts()
) :: build_result()
```

Builds the WebSocket authentication frame.

Returns `{:ok, message}` where `message` is a JSON-encodable map,
`:no_message` when the pattern doesn't send a standalone auth frame
(e.g. `listen_key`, `rest_token`, `inline_subscribe`), or `{:error, reason}`.

# `build_subscribe_auth`
*optional* 

```elixir
@callback build_subscribe_auth(
  credentials :: CCXT.Credentials.t(),
  config :: auth_config(),
  channel :: String.t() | nil,
  symbols :: [String.t()] | nil
) :: map() | nil
```

Optional: build auth data to include in subscribe frames.

For inline patterns (coinbase) and token patterns (kraken), auth data is
attached to each private subscribe. Default is no inline auth.

# `handle_auth_response`

```elixir
@callback handle_auth_response(
  response :: auth_response(),
  state :: auth_state()
) :: handle_result()
```

Handles the authentication response frame.

Returns `:ok` on success, `{:ok, auth_meta}` with metadata such as
`%{ttl_ms: 900_000}` for expiry scheduling (see `CCXT.WS.Auth.Expiry`),
or `{:error, reason}` on failure.

# `pre_auth`

```elixir
@callback pre_auth(
  credentials :: CCXT.Credentials.t(),
  config :: auth_config(),
  opts :: opts()
) :: pre_auth_result()
```

Performs pre-authentication (REST call for token/listen key).

Returns `{:ok, data}` with pre-auth data the caller needs to drive the
REST call and embed its result in the WS URL or subscribe frames.
Patterns that don't need pre-auth return `{:ok, %{}}`.

---

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