Add support to JWT Bearer

package.json

@@ -10,6 +10,7 @@
     "build": "pnpm --filter js-auth build",
     "prepare": "husky install",
     "test": "pnpm --filter js-auth test",
+    "test:watch": "pnpm --filter js-auth test:watch",
     "make:version": "lerna version --no-private",
     "example:cjs": "pnpm --filter cjs start",
     "example:esm": "pnpm --filter esm start",

packages/js-auth/README.md

@@ -17,6 +17,7 @@ A JavaScript Library wrapper that helps you use the Commerce Layer API for [Auth
   - [Integration application with client credentials flow](#integration-client-credentials)
   - [Webapp application with authorization code flow](#webapp-authorization-code)
   - [Provisioning application](#provisioning)
+  - [JWT bearer](#jwt-bearer)
 - [Utilities](#utilities)
   - [Decode an access token](#decode-an-access-token)
 - [Contributors guide](#contributors-guide)
@@ -205,6 +206,50 @@ console.log('My access token: ', auth.accessToken)
 console.log('Expiration date: ', auth.expires)
 ```
 
+### JWT bearer
+
+Commerce Layer, through OAuth2, provides the support of token exchange in the _on-behalf-of_ (delegation) scenario which allows,
+for example, to make calls on behalf of a user and get an access token of the requesting user without direct user interaction.
+**Sales channels** and **webapps** can accomplish it by leveraging the [JWT Bearer flow](https://docs.commercelayer.io/core/authentication/jwt-bearer),
+which allows a client application to obtain an access token using a JSON Web Token (JWT) [_assertion_](https://docs.commercelayer.io/core/authentication/jwt-bearer#creating-the-jwt-assertion).
+
+You can use this code to create an _assertion_:
+
+```ts
+const assertion = await createAssertion({
+  payload: {
+    'https://commercelayer.io/claims': {
+      owner: {
+        type: 'Customer',
+        id: '4tepftJsT2'
+      },
+      custom_claim: {
+        customer: {
+          first_name: 'John',
+          last_name: 'Doe'
+        }
+      }
+    }
+  }
+})
+```
+
+You can now get an access token using the `urn:ietf:params:oauth:grant-type:jwt-bearer` grant type:
+
+```ts
+import { authenticate } from '@commercelayer/js-auth'
+
+const auth = await authenticate('urn:ietf:params:oauth:grant-type:jwt-bearer', {
+  clientId: 'your-client-id',
+  clientSecret: 'your-client-secret',
+  scope: 'market:code:europe',
+  assertion
+})
+
+console.log('My access token: ', auth.accessToken)
+console.log('Expiration date: ', auth.expires)
+```
+
 ## Utilities
 
 ### Decode an access token

packages/js-auth/package.json

@@ -35,14 +35,17 @@
     "lint": "eslint src --ext .ts,.tsx",
     "lint:fix": "eslint src --ext .ts,.tsx --fix",
     "test": "pnpm run lint && vitest run --silent",
+    "test:watch": "vitest --silent",
     "build": "tsup"
   },
   "publishConfig": {
     "access": "public"
   },
   "license": "MIT",
   "devDependencies": {
+    "@types/jsonwebtoken": "^9.0.6",
     "@types/node": "^20.11.27",
+    "jsonwebtoken": "^9.0.2",
     "tsup": "^8.0.2",
     "typescript": "^5.4.2",
     "vite-tsconfig-paths": "^4.3.2",

packages/js-auth/src/index.ts

@@ -1,4 +1,5 @@
 export { authenticate } from './authenticate.js'
+
 export {
   jwtDecode,
   jwtIsDashboard,
@@ -8,6 +9,8 @@ export {
   jwtIsWebApp
 } from './jwtDecode.js'
 
+export { createAssertion } from './jwtEncode.js'
+
 export type {
   AuthenticateOptions,
   AuthenticateReturn,

packages/js-auth/src/jwtDecode.ts

@@ -1,33 +1,17 @@
+import { decodeBase64URLSafe } from '#utils/base64.js'
+
 /**
  * Decode a Commerce Layer access token.
  */
 export function jwtDecode(accessToken: string): CommerceLayerJWT {
   const [header, payload] = accessToken.split('.')
 
   return {
-    header: JSON.parse(header != null ? atob(header) : 'null'),
-    payload: JSON.parse(payload != null ? atob(payload) : 'null')
+    header: JSON.parse(header != null ? decodeBase64URLSafe(header) : 'null'),
+    payload: JSON.parse(payload != null ? decodeBase64URLSafe(payload) : 'null')
   }
 }
 
-/**
- * The `atob()` function decodes a string of data
- * which has been encoded using [Base64](https://developer.mozilla.org/en-US/docs/Glossary/Base64) encoding.
- *
- * This method works both in Node.js and browsers.
- *
- * @link [MDN Reference](https://developer.mozilla.org/en-US/docs/Web/API/atob)
- * @param encodedData A binary string (i.e., a string in which each character in the string is treated as a byte of binary data) containing base64-encoded data.
- * @returns An ASCII string containing decoded data from `encodedData`.
- */
-function atob(encodedData: string): string {
-  if (typeof window !== 'undefined') {
-    return window.atob(encodedData)
-  }
-
-  return Buffer.from(encodedData, 'base64').toString('binary')
-}
-
 interface CommerceLayerJWT {
   /** The header typically consists of two parts: the type of the token, which is JWT, and the signing algorithm being used, such as HMAC SHA256 or RSA. */
   header: {

packages/js-auth/src/jwtEncode.spec.ts

@@ -0,0 +1,26 @@
+import jwt from 'jsonwebtoken'
+import { createAssertion } from './jwtEncode.js'
+
+describe('createAssertion', () => {
+  it('should be able to create a JWT assertion.', async () => {
+    const payload = {
+      'https://commercelayer.io/claims': {
+        owner: {
+          type: 'User',
+          id: '1234'
+        },
+        custom_claim: {
+          name: 'John'
+        }
+      }
+    } as const
+
+    const jsonwebtokenAssertion = jwt.sign(payload, 'cl', {
+      algorithm: 'HS512'
+    })
+
+    const assertion = await createAssertion({ payload })
+
+    expect(assertion).toStrictEqual(jsonwebtokenAssertion)
+  })
+})

packages/js-auth/src/jwtEncode.ts

@@ -0,0 +1,94 @@
+import { encodeBase64URLSafe } from '#utils/base64.js'
+
+interface Owner {
+  type: 'User' | 'Customer'
+  id: string
+}
+
+/**
+ * Create a JWT assertion as the first step of the [JWT bearer token authorization grant flow](https://docs.commercelayer.io/core/authentication/jwt-bearer).
+ *
+ * The JWT assertion is a digitally signed JSON object containing information
+ * about the client and the user on whose behalf the access token is being requested.
+ *
+ * This JWT assertion can include information such as the issuer (typically the client),
+ * the owner (the user on whose behalf the request is made), and any other relevant claims.
+ *
+ * @example
+ * ```ts
+ * const assertion = await createAssertion({
+ *   payload: {
+ *     'https://commercelayer.io/claims': {
+ *       owner: {
+ *         type: 'Customer',
+ *         id: '4tepftJsT2'
+ *       },
+ *       custom_claim: {
+ *         customer: {
+ *           first_name: 'John',
+ *           last_name: 'Doe'
+ *         }
+ *       }
+ *     }
+ *   }
+ * })
+ * ```
+ */
+export async function createAssertion({ payload }: Assertion): Promise<string> {
+  return await jwtEncode(payload, 'cl')
+}
+
+interface Assertion {
+  /** Assertion payload. */
+  payload: {
+    'https://commercelayer.io/claims': {
+      /** The customer or user you want to make the calls on behalf of. */
+      owner: Owner
+      /** Any other information (key/value pairs) you want to enrich the token with. */
+      custom_claim?: Record<string, unknown>
+    }
+  }
+}
+
+async function jwtEncode(
+  payload: Record<string, unknown>,
+  secret: string
+): Promise<string> {
+  const header = { alg: 'HS512', typ: 'JWT' }
+
+  const encodedHeader = encodeBase64URLSafe(JSON.stringify(header))
+
+  const encodedPayload = encodeBase64URLSafe(
+    JSON.stringify({
+      ...payload,
+      iat: Math.floor(new Date().getTime() / 1000)
+    })
+  )
+
+  const unsignedToken = `${encodedHeader}.${encodedPayload}`
+
+  const signature = await createSignature(unsignedToken, secret)
+
+  return `${unsignedToken}.${signature}`
+}
+
+async function createSignature(data: string, secret: string): Promise<string> {
+  const enc = new TextEncoder()
+  const algorithm = { name: 'HMAC', hash: 'SHA-512' }
+
+  const key = await crypto.subtle.importKey(
+    'raw',
+    enc.encode(secret),
+    algorithm,
+    false,
+    ['sign', 'verify']
+  )
+
+  const signature = await crypto.subtle.sign(
+    algorithm.name,
+    key,
+    enc.encode(data)
+  )
+
+  return encodeBase64URLSafe(String.fromCharCode(...new Uint8Array(signature)))
+}

packages/js-auth/src/types/index.ts

@@ -6,6 +6,7 @@ import type { TBaseReturn } from './base.js'
 import type { TClientCredentialsOptions } from './clientCredentials.js'
 import type { TPasswordOptions, TPasswordReturn } from './password.js'
 import type { TRefreshTokenOptions } from './refreshToken.js'
+import type { TJwtBearerOptions, TJwtBearerReturn } from './jwtBearer.js'
 
 /**
  * The grant type.
@@ -15,25 +16,30 @@ export type GrantType =
   | 'refresh_token'
   | 'client_credentials'
   | 'authorization_code'
+  | 'urn:ietf:params:oauth:grant-type:jwt-bearer'
 
 export type AuthenticateOptions<TGrantType extends GrantType> =
-  TGrantType extends 'password'
-    ? TPasswordOptions
-    : TGrantType extends 'refresh_token'
-      ? TRefreshTokenOptions
-      : TGrantType extends 'client_credentials'
-        ? TClientCredentialsOptions
-        : TGrantType extends 'authorization_code'
-          ? TAuthorizationCodeOptions
-          : never
+  TGrantType extends 'urn:ietf:params:oauth:grant-type:jwt-bearer'
+    ? TJwtBearerOptions
+    : TGrantType extends 'password'
+      ? TPasswordOptions
+      : TGrantType extends 'refresh_token'
+        ? TRefreshTokenOptions
+        : TGrantType extends 'client_credentials'
+          ? TClientCredentialsOptions
+          : TGrantType extends 'authorization_code'
+            ? TAuthorizationCodeOptions
+            : never
 
 export type AuthenticateReturn<TGrantType extends GrantType> =
-  TGrantType extends 'password'
-    ? TPasswordReturn
-    : TGrantType extends 'refresh_token'
+  TGrantType extends 'urn:ietf:params:oauth:grant-type:jwt-bearer'
+    ? TJwtBearerReturn
+    : TGrantType extends 'password'
       ? TPasswordReturn
-      : TGrantType extends 'client_credentials'
-        ? TBaseReturn
-        : TGrantType extends 'authorization_code'
-          ? TAuthorizationCodeReturn
-          : never
+      : TGrantType extends 'refresh_token'
+        ? TPasswordReturn
+        : TGrantType extends 'client_credentials'
+          ? TBaseReturn
+          : TGrantType extends 'authorization_code'
+            ? TAuthorizationCodeReturn
+            : never

packages/js-auth/src/types/jwtBearer.ts

@@ -0,0 +1,30 @@
+import type { TBaseOptions } from '#types/base.js'
+import type { TPasswordReturn } from './password.js'
+
+/**
+ * Commerce Layer, through OAuth2, provides the support of token exchange in the on-behalf-of (delegation) scenario which allows,
+ * for example, to make calls on behalf of a user and get an access token of the requesting user without direct user interaction.
+ * Sales channels and webapps can accomplish it by leveraging the JWT Bearer flow,
+ * which allows a client application to obtain an access token using a JSON Web Token (JWT) assertion.
+ * @see https://docs.commercelayer.io/core/authentication/jwt-bearer
+ */
+export interface TJwtBearerOptions extends TBaseOptions {
+  /** Your application's client secret. */
+  clientSecret: string
+  /**
+   * A single JSON Web Token ([learn more](https://docs.commercelayer.io/core/authentication/jwt-bearer#creating-the-jwt-assertion)).
+   * Max size is 4KB.
+   *
+   * **You can use the `createAssertion` helper method**.
+   *
+   * @example
+   * ```ts
+   * import { createAssertion } from '@commercelayer/js-auth'
+   * ```
+   */
+  assertion: string
+}
+
+export interface TJwtBearerReturn extends Omit<TPasswordReturn, 'ownerType'> {
+  ownerType: 'user' | 'customer'
+}