verify-rsa-jwt-cloudflare-worker
v1.4.0
Published
Verify RSA JWT on Cloudflare Workers
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verify-rsa-jwt-cloudflare-worker
This is a lightweight library that verifies a JWT (JSON Web Token) signed with RS256. This is built for Cloudflare Workers.
Although, the project itself has no dependencies. If the runtime supports Web Standard APIs, it should just work :tm:
This package includes the Hono Middleware :fire:
It uses JWKS to verify a JWT. To fetch JWKS, you need to provide the JWKs endpoint URL to JWKS_URI.
Install
npm install verify-rsa-jwt-cloudflare-worker
Usage
Module Worker
import {
getJwks,
useKVStore,
verify,
VerifyRsaJwtEnv,
} from "verify-rsa-jwt-cloudflare-worker";
export default {
async fetch(request: Request, env: VerifyRsaJwtEnv): Promise<Response> {
const token =
request.headers.get("Authorization")?.replace(/Bearer\s+/i, "") || "";
try {
const jwks = await getJwks(env.JWKS_URI, useKVStore(env.VERIFY_RSA_JWT));
const { payload } = await verify(token, jwks);
// Then, you could validate the payload and return a response
return new Response(JSON.stringify({ payload }), {
headers: { "content-type": "application/json" },
});
} catch (error: any) {
return new Response((error as Error).message, { status: 401 });
}
},
};
wrangler.toml
name = "verify-rsa-jwt-cloudflare-worker"
compatibility_date = "2023-05-18"
[vars]
JWKS_URI = "https://<your-authorization-server-host>/.well-known/jwks.json"
VERIFY_RSA_JWT_JWKS_CACHE_KEY = ""
[[kv_namespaces]]
binding = "VERIFY_RSA_JWT"
id = "<ID CREATED BY WRANGLER>"
preview_id = "<ID CREATED BY WRANGLER>"
Use Without a KV Store
If you do not want to use a KV store to cache the JWKS returned by getJwks()
, you can omit the second parameter.
const jwks = await getJwks("https://<myurl>/.well-known/jwks.json");
[!WARNING] Not caching the JWKS in a KV store will result in longer response times since the JWKS must be refetched on every request. It can also lead to request throttling from the JWKS provider if your Worker receives a lot of traffic.
Hono Middleware
The middleware provides authentication by verifying the token with RSA-JWT. Authorization header value or cookie value specified by the cookie option will be used as a token.
If you are working on a Cloudflare Workers based project, the following parameters can be set via wrangler.toml
.
VerifyRsaJwtEnv
| Variable | Description |
| ----------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| VERIFY_RSA_JWT | KVNamespace. It want to store downloaded JWKS |
| VERIFY_RSA_JWT_JWKS_CACHE_KEY | Optional string to specify what key we want to sue to store JWKS. Default: verify-rsa-jwt-cloudflare-worker-jwks-cache-key
|
| JWKS_URI | A URI for downloading JWKS. Typically https://<host>/.well-known/jwks.json
|
| JWKS | Optional. Instead of giving the URI, You could provide hardcoded jwks. |
Additionally, or, if you are working on a non-Cloudflare Workers based project, such as Node.js, the following optional config values are available:
VerifyRsaJwtConfig
| Variable | Description |
| ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| jwksUri | A URI for downloading JWKS. |
| jwks | Optional. Instead of giving the URI, You could provide hardcoded jwks. |
| kvStore | Any storage manager that has get
and put
. It's used for storing JWKS. |
| payloadValidator | Every authentication vendor would configure JWT payload differently. Please give a function that validates the payload and throw an error. |
| verbose | A debug flag. |
Import
import { Hono } from "hono";
import {
verifyRsaJwt,
getPayloadFromContext,
createGetCookieByKey,
} from "verify-rsa-jwt-cloudflare-worker";
Hono Middleware Usage
Scenario 1: When the token is given via the Authorization header.
const app = new Hono()
app.use(
'/auth/*',
verifyRsaJwt({
jwksUri: "https://<host>/.well-known/jwks.json",
kvStore: // Anything that keeps a value, KVNamespace should work too.
payloadValidator: ({payload, ctx}) => { /* Validate the payload, throw an error if invalid */ },
})
)
Scenario 2: When the token is given via the Cookie header.
import { getCookie } from "hono/cookie";
const app = new Hono()
app.use(
'/auth/*',
verifyRsaJwt({
getCookieByKey: createGetCookieByKey(getCookie, "access_token"), // "access_token" is an example cookie key name where you want to fetch a JWT from.
jwksUri: "https://<host>/.well-known/jwks.json",
kvStore: // Anything that keeps a value, KVNamespace should work too.
payloadValidator: ({payload, ctx}) => { /* Validate the payload, throw an error if invalid */ },
})
)
Get payload:
app.get("/auth/page", (c) => {
const claims = getPayloadFromContext(c);
return c.text("You are authorized");
});
Test
Automated tests
Some tests use PEM files to create JWT tokens / imitate JWKS. You need the following setup to prepare them.
Create a
.env
file.echo PEM_NAME="test-pem" > .env
Run
npm run gen-pem-keys
to generate PEM files.Then, as you may be familiar, test with
npm test
.
Manual test
For testing through src/worker.ts
, you can:
Launch a local server
npm run start src/worker.ts
cURL with your JWT!
url -H "Authorization: Bearer <YOUR-JWT>" http://127.0.0.1:<YOUR-DEV-SERVER-PORT>/
Then, if everything is set correctly, you'd expect to see something like this:
{ "payload": { "iss": " ... ", "sub": " ... ", "aud": " ... ", "iat": 1690401415, "exp": 1690487815, "azp": " ... ", "gty": " ... " } }
Development
Use Wrangler CLI
Please follow this document. https://developers.cloudflare.com/workers/get-started/guide/.
Learn more about Authentication
Auth0 provides amazing documents.