aws4-express

This library is about to create on security layer of your API using well defined comunication standard known as AWS Signature V4.

We provide Express middleware handler awsVerify for validation your AWS Signature V4 with your access and secret pair of key. So, your web app can mimic AWS services, and you can use benefits from already well-defined standard to securing your web API.

At this moment, library is based on general version of aws4 signature: Authenticating Requests (AWS Signature Version 4)

Beta stage

Until we hit >=1.x.x, there could be possible breaking changes on minor changes. Use at least 0.8.0 version.

Install

1npm install aws4-express

Use

There are prepared helpers to handle the original body with any changes, because if you change a single character, your request won't be valid anymore.

If you use express parsers like express.raw() or express.json() or express.urlencoded you can attach with handler rawBodyFromVerify. You can also write own stream parser or use our rawBodyFromStream.

1  import express from 'express';
2  import { awsVerify, rawBodyFromVerify, rawBodyFromStream } from 'aws4-express';
3
4  const app = express();
5  // whenever you may need to get original body string and you case
6  // when json parser u may use like this
7  app.use(
8    express.json({
9      type: '*/*',
10      verify: rawBodyFromVerify,
11    }),
12  );
13
14  // or when json parser u may use like this
15  app.use(
16    express.raw({
17      type: '*/*',
18      verify: rawBodyFromVerify,
19    })
20  );
21
22  // or when url encoded body u may use like this
23  app.use(
24    express.urlencoded({
25      extended: true,
26      type: '*/*',
27      verify: rawBodyFromVerify,
28    }),
29  );
30
31  // or events on when json parser u may use like this
32  app.use(rawBodyFromStream);
33
34  // main handler to authorization incomming requests:
35  app.use(awsVerify({
36    secretKey: (message, req, res, next) => {
37      // fetch secret key from your storage key/secret pairs (sql, nosql, memory)
38      // you have to provide your own secret provider here.
39      // retrun string | undefined
40
41      return getMySecretByKey(message.accessKey),
42    }
43  }));
44
45  // your routers ...
46  app.all('*', ...);
47  app.get('/get', ...);
48  app.post('/post', ...);
49
50  return app;

Example:

• simpleIntegration.ts

Features:

• General implementation standard: aws4 signature.
• Fully customized.
• No strict rules on services, regions you can name it as you want as long your signing client support this.
• Single chunk request
• Tests with client: aws4
• Query headers x-amz-*,
• Multiple chunks (no x-amz-decoded-content-length)

Supported headers:

• authorization - [required] must have in proper format: Authorization: AWS4-HMAC-SHA256 Credential=ACCESS_KEY/DATE/REGION/SERVICE/TYPE_REQUEST, SignedHeaders=< SIGNED_HEADERS>, Signature=SIGNATURE :
  • ACCESS_KEY - any text without whitespaces and slashes (/) - Only have to do is handle distribution of access_key, secret_key and these keys have to be accessible on the server side.
  • DATE - is part of X-AMZ-DATE: in format YYYYMMDD.
  • REGION - any thing you need in this place or use something from amz regions.
  • SERVICE - any thing you need in this place or 'execute-api' for sake of simplicity.
  • TYPE_REQUEST - you can use your variations instead of standard 'aws4_request'.
  • SIGNED_HEADERS - all signed headers - more headers mean harder to temper request. Required headers at this moment: host:x-amz-date
  • SIGNATURE - calculated signature based on Authenticating Requests (AWS Signature Version 4)
• x-amz-date - [required] must have in request to valid request signature
• x-amz-content-sha256 - [optional] you can attach precalculated hash. When X-Amz-Content-Sha256 is sent we skip calculating hash from body. This way is less secure and recommended use at least with X-Amz-Expires.
  • There can provide your validation whenever you want handle this header onBeforeParse or onAfterParse.
  • You can also send UNSIGNED-PAYLOAD instead of sha-256 signature - this cloud speed up your bigger request, but signature will be same as long as headers remain same.
  • You can put your signature (most client don't include these headers) - should be calculated in this way:

    crypto.createHash('sha256').update(data, 'utf8').digest('hex')
    

• x-amz-expires - [optional] - format: YYYY-mm-ddTHH:MM:SS. If you want valid your request for a period of time and don't want to reuse signature when time is up.

Pull Requests are welcome.

Documentation

awsVerify Function Documentation

Overview

The awsVerify function is an Express.js middleware that verifies AWS signatures in incoming requests.

Usage

1import { awsVerify } from 'aws4-express';
2
3app.use(awsVerify(options));

Parameters

• options: An object of type AwsVerifyOptions

Return Value

Returns an Express.js middleware function.

Configuration: AwsVerifyOptions

The AwsVerifyOptions object can contain the following fields:

secretKey (required)

• Type: (message: AwsIncomingMessage, req: Request, res: Response, next: NextFunction) => Promise<string | undefined> | string | undefined
• Description: Callback for retrieving the secret key. Should return the secret key based on incoming parameters or undefined if the key is not available.

headers (optional)

• Type: (headers: Dictionary) => Promise<Dictionary> | Dictionary
• Description: Callback for modifying incoming headers before the parsing process.

enabled (optional)

• Type: (req: Request) => Promise<boolean> | boolean
• Description: Function determining whether AWS signature validation should be performed. If it returns false, validation will be skipped.

onMissingHeaders (optional)

• Type: (req: Request, res: Response, next: NextFunction) => Promise<void> | void
• Description: Custom response when required headers are missing.
• Default: Sends a 400 status with the message "Required headers are missing".

onSignatureMismatch (optional)

• Type: (req: Request, res: Response, next: NextFunction) => Promise<void> | void
• Description: Custom response when the signature doesn't match.
• Default: Sends a 401 status with the message "The signature does not match".

onExpired (optional)

• Type: (req: Request, res: Response, next: NextFunction) => Promise<void> | void
• Description: Custom response when the signature has expired.
• Default: Sends a 401 status with the message "Request is expired".

onBeforeParse (optional)

• Type: (req: Request, res: Response, next: NextFunction) => Promise<boolean> | boolean
• Description: Callback invoked before the standard parser. If it returns false, validation will be stopped.
• Default: Always returns true.

onAfterParse (optional)

• Type: (message: AwsIncomingMessage, req: Request, res: Response, next: NextFunction) => Promise<boolean> | boolean
• Description: Callback invoked after the standard parser completes. If it returns false, validation will be stopped.
• Default: Always returns true.

onSuccess (optional)

• Type: (message: AwsIncomingMessage | undefined, req: Request, res: Response, next: NextFunction) => Promise<void> | void
• Description: Callback invoked after successful signature validation.
• Default: Calls next().

Example

1import express from 'express';
2import { awsVerify, rawBodyFromVerify } from 'aws4-express';
3
4const app = express();
5
6app.use(express.json({ type: '*/*', verify: rawBodyFromVerify }));
7
8app.use(awsVerify({
9  secretKey: async (message) => {
10    // Implement secret key retrieval logic
11    return 'your_secret_key';
12  },
13  onSignatureMismatch: (req, res) => {
14    res.status(403).send('Unauthorized');
15  }
16}));
17
18app.get('/', (req, res) => {
19  res.send('Hello, AWS-verified world!');
20});
21
22app.listen(3000, () => {
23  console.log('Server is running on port 3000');
24});

In this example, the awsVerify middleware is used to verify the AWS signature for all incoming requests. A custom secretKey function is used to provide the secret key, and onSignatureMismatch defines a custom response for signature mismatch cases.

awsVerify:

Complete options configuration for awsVerify:

1express.use(awsVerify({
2  secretKey: (message: AwsIncomingMessage, req: Request, res: Response, next: NextFunction) => Promise<string | undefined> | string | undefined;
3  headers?: (headers: Dictionary) => Promise<Dictionary> | Dictionary;
4  enabled?: (req: Request) => Promise<boolean> | boolean;
5  onMissingHeaders?: (req: Request, res: Response, next: NextFunction) => Promise<void> | void;
6  onSignatureMismatch?: (req: Request, res: Response, next: NextFunction) => Promise<void> | void;
7  onExpired?: (req: Request, res: Response, next: NextFunction) => Promise<void> | void;
8  onBeforeParse?: (req: Request, res: Response, next: NextFunction) => Promise<boolean> | boolean;
9  onAfterParse?: (
10    message: AwsIncomingMessage,
11    req: Request,
12    res: Response,
13    next: NextFunction,
14  ) => Promise<boolean> | boolean;
15  onSuccess?: (
16    message: AwsIncomingMessage | undefined,
17    req: Request,
18    res: Response,
19    next: NextFunction,
20  ) => Promise<void> | void;
21}))

Default values for all optional configuration for awsVerify:

1  {
2      enabled: () => true,
3      headers: (req) => req.headers,
4      onExpired: (res) => {
5        res.status(401).send('Request is expired');
6      },
7      onMissingHeaders: (res) => {
8        res.status(400).send('Required headers are missing');
9      },
10      onSignatureMismatch: (res) => {
11        res.status(401).send('The signature does not match');
12      },
13      onBeforeParse: () => true,
14      onAfterParse: () => true,
15      onSuccess: () => next()
16  }