# Keypairs for node.js

Lightweight JavaScript RSA and ECDSA utils that work on Windows, Mac, and Linux
using modern node.js APIs (no need for C compiler).

A thin wrapper around [Eckles.js (ECDSA)](https://git.coolaj86.com/coolaj86/eckles.js/)
and [Rasha.js (RSA)](https://git.coolaj86.com/coolaj86/rasha.js/).

# Features

  * [x] Generate keypairs
    * [x] RSA
    * [x] ECDSA (P-256, P-384)
  * [x] PEM-to-JWK
  * [x] JWK-to-PEM
  * [x] SHA256 JWK Thumbprints
  * [ ] JWK fetching. See [Keyfetch.js](https://npmjs.com/packages/keyfetch/)
    * [ ] OIDC
    * [ ] Auth0

<!--

  * [ ] sign JWS
  * [ ] generate CSR (DER as PEM or base64url)

-->

# Usage

A brief (albeit somewhat nonsensical) introduction to the APIs:

```
Keypairs.generate().then(function (pair) {
  return Keypairs.export({ jwk: pair.private }).then(function (pem) {
    return Keypairs.import({ pem: pem }).then(function (jwk) {
      return Keypairs.thumbprint({ jwk: jwk }).then(function (thumb) {
        console.log(thumb);
        return Keypairs.signJwt({
          jwk: keypair.private
        , claims: {
            iss: 'https://example.com'
          , sub: 'jon.doe@gmail.com'
          , exp: Math.round(Date.now()/1000) + (3 * 24 * 60 * 60)
          }
        });
      });
    });
  });
});
```

By default ECDSA keys will be used since they've had native support in node
_much_ longer than RSA has, and they're smaller, and faster to generate.

## API Overview

#### Keypairs.generate(options)

Generates a public/private pair of JWKs as `{ private, public }`

Option examples:

  * RSA `{ kty: 'RSA', modulusLength: 2048 }`
  * ECDSA `{ kty: 'ECDSA', namedCurve: 'P-256' }`

When no options are supplied EC P-256 (also known as `prime256v1` and `secp256r1`) is used by default.

#### Keypairs.import({ pem: '...' }

Takes a PEM in pretty much any format (PKCS1, SEC1, PKCS8, SPKI) and returns a JWK.

#### Keypairs.export(options)

Exports a JWK as a PEM.

Exports PEM in PKCS8 (private) or SPKI (public) by default.

Options

```js
{ jwk: jwk
, public: true
, encoding: 'pem' // or 'der'
, format: 'pkcs8' // or 'ssh', 'pkcs1', 'sec1', 'spki'
}
```

#### Keypairs.thumbprint({ jwk: jwk })

Promises a JWK-spec thumbprint: URL Base64-encoded sha256

#### Keypairs.signJwt({ jwk, header, claims })

Returns a JWT (otherwise known as a protected JWS in "compressed" format).

```js
{ jwk: jwk
, claims: {
  }
}
```

Header defaults:

```js
{ kid: thumbprint
, alg: 'xS256'
, typ: 'JWT'
}
```

Payload notes:

* `iat: now` is added by default (set `false` to disable)
* `exp` must be set (set `false` to disable)
* `iss` should be the base URL for JWK lookup (i.e. via OIDC, Auth0)

Notes:

`header` is actually the JWS `protected` value, as all JWTs use protected headers (yay!)
and `claims` are really the JWS `payload`.

#### Keypairs.signJws({ jwk, header, protected, payload })

This is provided for APIs like ACME (Let's Encrypt) that use uncompressed JWS (instead of JWT, which is compressed).

Options:

* `header` not what you think. Leave undefined unless you need this for the spec you're following.
* `protected` is the typical JWT-style header
  * `kid` and `alg` will be added by default (these are almost always required), set `false` explicitly to disable
* `payload` can be JSON, a string, or even a buffer (which gets URL Base64 encoded)
  * you must set this to something, even if it's an empty string, object, or Buffer

# Additional Documentation

Keypairs.js provides a 1-to-1 mapping to the Rasha.js and Eckles.js APIs,
but it also includes the additional convenience methods `signJwt` and `signJws`.

That is to say that any option you pass to Keypairs will be passed directly to the corresponding API
of either Rasha or Eckles.

* See ECDSA documentation at [Eckles.js](https://git.coolaj86.com/coolaj86/eckles.js/)
* See RSA documentation at [Rasha.js](https://git.coolaj86.com/coolaj86/rasha.js/)