createVincentUserMiddleware

createVincentUserMiddleware<UserKey>(config): object

Defined in: app-sdk/src/expressMiddleware/express.ts:79

Returns an Express middleware function to authenticate a user using a JWT token, and a type-guard wrapper function for type-safe usage of route handlers guarded by the middleware.

The middleware() function:

• Checks the Authorization header for a Bearer token, verifies the token, and checks its audience.
• If the token is valid, it attaches the user information (decoded JWT, and raw JWT string) to the request object
• If the token is missing or invalid, it returns a 401 Unauthorized response with an error message.

Designate what field on req should be set with the JWT with the userKey configuration option.

The handler() function:

• Provides a type-safe reference to req where the userKey you have provided is correctly inferred to the appropriate type
• Note that it is still your responsibility to ensure you have attached the middleware somewhere in the chain before you use the handler()
  • If you forget, the handler() function will throw an error if the expected req[userKey] does not exist.

See express.js documentation for details on writing your route handler

Type Parameters

UserKey

UserKey extends string

Parameters

config

allowedAudience

string

requiredAppId

undefined | number

userKey

UserKey

Returns

object

handler()

handler: (handler) => (req, res, next) => void | Promise<void>

Parameters

handler

AuthenticatedRequestHandler<UserKey>

Returns

(req, res, next): void | Promise<void>

Parameters

req

Request

res

Response

next

NextFunction

Returns

void | Promise<void>

middleware()

middleware: (req, res, next) => Promise<void>

Parameters

req

Request

res

Response

next

NextFunction

Returns

Promise<void>

Example

import { createVincentUserMiddleware } from '@lit-protocol/vincent-app-sdk/expressMiddleware';

// In your environment configuration
const ALLOWED_AUDIENCE = 'https://yourapp.example.com';
const VINCENT_APP_ID = 555; // Provided by the vincent app registry

const { middleware, handler } = createVincentUserMiddleware({
 allowedAudience: ALLOWED_AUDIENCE,
 requiredAppId: VINCENT_APP_ID,
 userKey: 'vincentUser',
});

// Apply to routes that require authentication; req is guaranteed authenticated because it is wrapped in `handler()`
app.get('/protected-resource', middleware, handler((req, res) => {
    // handler() gives you the correct inferred type of `req[userKey]`
    const pkpAddress = req.vincentUser.decodedJWT.payload.pkp.ethAddress;
    const appInfo = req.vincentUser.decodedJWT.payload.app;

    if(appInfo) {
      res.json({ message: `Hello, user with PKP address ${pkpAddress}. You are authenticated for app ${appInfo.id} @ v${appInfo.version}` });
      return;
    }

    res.json({ message: `Hello, user with PKP address ${pkpAddress}.` });
  })
);

See the code below for the implementation used by the middleware returned by this function. You can adapt this logic to the HTTP framework of your choice.