# `Joken.Signer`
[🔗](https://github.com/joken-elixir/joken/blob/v2.7.0/lib/joken/signer.ex#L1)

Interface between Joken and JOSE for signing and verifying tokens.

In the future we plan to keep this interface but make it pluggable for other crypto
implementations like using only standard `:crypto` and `:public_key` modules. So,
**avoid** depending on the inner structure of this module.

# `key`

```elixir
@type key() :: binary() | map()
```

A key may be an octet or a map with parameters according to JWK (JSON Web Key)

# `t`

```elixir
@type t() :: %Joken.Signer{
  alg: binary() | nil,
  jwk: JOSE.JWK.t() | nil,
  jws: JOSE.JWS.t() | nil
}
```

A `Joken.Signer` instance is a JWS (JSON Web Signature) and JWK (JSON Web Key) struct.

It also contains an `alg` field for performance reasons.

# `algorithms`

```elixir
@spec algorithms() :: [binary()]
```

All supported algorithms.

# `create`

```elixir
@spec create(binary(), key(), %{required(binary()) => term()}) :: t()
```

Creates a new Joken.Signer struct. Can accept either a binary for HS*** algorithms
or a map with arguments for the other kinds of keys. Also, accepts an optional map
that will be passed as extra header arguments for generated JWT tokens.

## Example

    iex> Joken.Signer.create("HS256", "s3cret")
    %Joken.Signer{
      alg: "HS256",
      jwk: %JOSE.JWK{
        fields: %{},
        keys: :undefined,
        kty: {:jose_jwk_kty_oct, "s3cret"}
      },
      jws: %JOSE.JWS{
        alg: {:jose_jws_alg_hmac, :HS256},
        b64: :undefined,
        fields: %{"typ" => "JWT"}
      }
    }

# `map_key_algorithms`

```elixir
@spec map_key_algorithms() :: [binary()]
```

Map key algorithms.

# `parse_config`

```elixir
@spec parse_config(atom()) :: t() | nil
```

Generates a `Joken.Signer` from Joken's application configuration.

A `Joken.Signer` has an algorithm (one of ["HS256", "HS384", "HS512", "RS256", "RS384", "RS512", "ES256", "ES384", "ES512", "PS256", "PS384", "PS512", "Ed25519", "Ed25519ph", "Ed448", "Ed448ph", "EdDSA"]) and a key.

There are several types of keys used by JWTs algorithms:

  - RSA
  - Elliptic Curve
  - Octet (binary)
  - So on...

Also, they can be encoded in several ways:

  - Raw (map of parameters)
  - PEM (Privacy Enhanced Mail format)
  - Open SSH encoding
  - So on...

To ease configuring these types of keys used by JWTs algorithms, Joken accepts a few
parameters in its configuration:

  - `:signer_alg` : one of ["HS256", "HS384", "HS512", "RS256", "RS384", "RS512", "ES256", "ES384", "ES512", "PS256", "PS384", "PS512", "Ed25519", "Ed25519ph", "Ed448", "Ed448ph", "EdDSA"].
  - `:key_pem` : a binary containing a key in PEM encoding format.
  - `:key_openssh` : a binary containing a key in Open SSH encoding format.
  - `:key_map` : a map with the raw parameters.
  - `:key_octet` : a binary used as the password for HS algorithms only.

## Examples

    config :joken,
      hs256: [
        signer_alg: "HS256",
        key_octet: "test"
      ]

    config :joken,
      rs256: [
        signer_alg: "RS256",
        key_pem: """
        -----BEGIN RSA PRIVATE KEY-----
        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
        -----END RSA PRIVATE KEY-----
        """
        ]

# `sign`

```elixir
@spec sign(Joken.claims(), t()) ::
  {:ok, Joken.bearer_token()} | {:error, Joken.error_reason()}
```

Signs a map of claims with the given Joken.Signer.

## Examples

    iex> Joken.Signer.sign(%{"name" => "John Doe"}, Joken.Signer.create("HS256", "secret"))
    {:ok, "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJuYW1lIjoiSm9obiBEb2UifQ.xuEv8qrfXu424LZk8bVgr9MQJUIrp1rHcPyZw_KSsds"}

    iex> Joken.Signer.sign(%{"name" => "John Doe"}, Joken.Signer.parse_config(:rs256))
    {:ok, "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJuYW1lIjoiSm9obiBEb2UifQ.e3hyn_oaaA2lxMlqH1UPo8STN-a_sszl8B2_s6tY9aT_YBAmfd7BXJOPsOMl7x2wXeKMQaNBVjna2tA0UiO_m3SpwiYgoTcU65D6OgkzugmLD_DhjDK1YCOKlm7So1uhbkb_QCuo4Ij5scsQqwv7hkxo4IximGBeH9LAvPhPTaGmYJMI7_tWIld2TlY6tNUQP4n0qctXsI3hjvGzdvuQW-tRnzAQCC4TYe-mJgFa033NSHeiX-sZB-SuYlWi7DJqDTiwlb_beVdqWpxxtFDA005Iw6FZTpH9Rs1LVwJU5t3RN5iWB-z4ZI-kKsGUGLNrAZ7btV6Ow2FMAdj9TXmNpQ"}

# `verify`

```elixir
@spec verify(Joken.bearer_token(), %Joken.Signer{
  alg: term(),
  jwk: term(),
  jws: term()
}) ::
  {:ok, Joken.claims()} | {:error, Joken.error_reason()}
```

Verifies the given token's signature with the given `Joken.Signer`.

## Examples

    iex> Joken.Signer.verify("eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJuYW1lIjoiSm9obiBEb2UifQ.xuEv8qrfXu424LZk8bVgr9MQJUIrp1rHcPyZw_KSsds", Joken.Signer.create("HS256", "secret"))
    {:ok, %{"name" => "John Doe"}}

    iex> Joken.Signer.verify("eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJuYW1lIjoiSm9obiBEb2UifQ.e3hyn_oaaA2lxMlqH1UPo8STN-a_sszl8B2_s6tY9aT_YBAmfd7BXJOPsOMl7x2wXeKMQaNBVjna2tA0UiO_m3SpwiYgoTcU65D6OgkzugmLD_DhjDK1YCOKlm7So1uhbkb_QCuo4Ij5scsQqwv7hkxo4IximGBeH9LAvPhPTaGmYJMI7_tWIld2TlY6tNUQP4n0qctXsI3hjvGzdvuQW-tRnzAQCC4TYe-mJgFa033NSHeiX-sZB-SuYlWi7DJqDTiwlb_beVdqWpxxtFDA005Iw6FZTpH9Rs1LVwJU5t3RN5iWB-z4ZI-kKsGUGLNrAZ7btV6Ow2FMAdj9TXmNpQ", Joken.Signer.parse_config(:rs256))
    {:ok, %{"name" => "John Doe"}}

---

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