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

Behaviour for signing pattern implementations.

First-party signing executors implement `sign/3` and are dispatched through
`Bourse.Signing.sign/4`. Runtime specs select only the closed built-in set.

## Available Helpers

`Bourse.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 :: Bourse.Signing.request(),
  credentials :: Bourse.Credentials.t(),
  config :: Bourse.Signing.config()
) :: Bourse.Signing.signed_request()
```

Signs a request using the pattern's authentication method.

## Parameters

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

## Returns

A `Bourse.Signing.SignedRequest` with `:url`, `:method`, `:headers`, and `:body`.

---

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