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

Behaviour for signing pattern implementations.

Any module implementing `sign/3` can be used as a signing pattern.
Built-in patterns are dispatched via `CCXT.Signing.sign/4`. Custom
modules are wired via `CCXT.Signing.Custom`.

## Implementing a Custom Pattern

    defmodule MyApp.Signing.MyExchange do
      @behaviour CCXT.Signing.Behaviour

      @impl true
      def sign(request, credentials, config) do
        timestamp = CCXT.Signing.timestamp_ms()
        signature = CCXT.Signing.hmac_sha256(
          request.path <> to_string(timestamp),
          credentials.secret
        )

        %{
          url: request.path,
          method: request.method,
          headers: [
            {"X-API-KEY", credentials.api_key},
            {"X-TIMESTAMP", to_string(timestamp)},
            {"X-SIGNATURE", CCXT.Signing.encode_hex(signature)}
          ],
          body: request.body
        }
      end
    end

## Available Helpers

`CCXT.Signing` provides crypto and encoding helpers:
`timestamp_ms/0`, `hmac_sha256/2`, `hmac_sha384/2`, `hmac_sha512/2`,
`sha256/1`, `sha512/1`, `encode_hex/1`, `encode_base64/1`,
`decode_base64/1`, `urlencode/1`, `urlencode_raw/1`.

# `sign`

```elixir
@callback sign(
  request :: CCXT.Signing.request(),
  credentials :: CCXT.Credentials.t(),
  config :: CCXT.Signing.config()
) :: CCXT.Signing.signed_request()
```

Signs a request using the pattern's authentication method.

## Parameters

- `request` - Map with `:method`, `:path`, `:body`, and `:params`
- `credentials` - `CCXT.Credentials` struct with API key and secret
- `config` - Pattern-specific configuration from the exchange spec

## Returns

A signed request map with `:url`, `:method`, `:headers`, and `:body`.

---

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