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Implement Passwordless Login via JavaScript Web Authentication

Last updated: December 13, 2024

Implementing passwordless login can increase both the security and convenience of your web application by allowing users to authenticate without the need for passwords. In this article, we will explore how to implement passwordless login using the Web Authentication API (WebAuthn) in JavaScript. WebAuthn is a W3C standard that enables secure authentication by using public key cryptography, effectively replacing passwords with more secure credentials.

Prerequisites

  • Basic knowledge of HTML, CSS, and JavaScript.
  • An understanding of server-side programming (Node.js or another backend language is beneficial).
  • A secure server setup with HTTPS, as browsers require secure contexts to use WebAuthn.

Basic WebAuthn Workflow

The passwordless login process using WebAuthn typically follows these steps:

  1. Registration: Users register their authenticator (e.g., a fingerprint scanner or USB security key) with the server.
  2. Challenge-response: During login, the server issues a challenge.
  3. Authentication: Users authenticate using their registered authenticator.

How to Implement Passwordless Login

Let's break down the implementation into specific parts, focusing primarily on the client side with JavaScript:

1. Setup the Registration Process

Begin by constructing a credential creation options object in your frontend JavaScript that conforms to the WebAuthn spec. This is used to ask a user's authenticator to generate a new public-private key pair.


const publicKey = {
  challenge: new Uint8Array([/* Random bytes generated by the server */]),
  rp: { name: "Example INC" },
  user: {
    id: new Uint8Array(/* User's unique identifier */),
    name: "[email protected]",
    displayName: "Username"
  },
  pubKeyCredParams: [
    { type: "public-key", alg: -7 }, // ECDSA with P-256
    { type: "public-key", alg: -257 } // RSA with SHA-256
  ]
};

Invoke the navigator.credentials.create() method using the constructed object. This method will interact with the user's authenticator device to create credentials.


navigator.credentials.create({ publicKey })
  .then((newCredential) => {
    // Process and send credentials to your server
  })
  .catch((err) => {
    console.error("Error creating credentials:", err);
  });

2. Authentication Process

After registration, to authenticate the user, prepare a options object for navigator.credentials.get().


const publicKeyGetRequest = {
  challenge: new Uint8Array([/* Server-generated challenge */]),
  allowCredentials: [{
    id: /* ID of the credential generated at registration */,
    type: 'public-key',
    transports: ['usb', 'ble', 'nfc']
  }]
};

navigator.credentials.get({ publicKey: publicKeyGetRequest })
  .then((assertion) => {
    // Handle authenticated response
  })
  .catch((err) => {
    console.error("Error authenticating:", err);
  });

Server-side Handling

On the server side, you will need to handle the credential generation and authentication steps securely. Important tasks include:

  • Challenge Generation: Must be cryptographically random to prevent replay attacks.
  • Validation: Verify signatures during authentication to ensure the credential is authentic.

Security Considerations

  • If possible, ensure that all cryptographic operations occur within a Trusted Platform Module (TPM) for additional security.
  • It’s crucial to properly manage the secure storage of keys and consistently update your security policies.

Conclusion

Implementing WebAuthn helps to secure web applications by eliminating password weakness as an entry point for attackers. Although this example mainly focused on JavaScript on the client side, a fully functional passwordless login involves significant server-side logic, mostly related to generating challenges, storing credential public keys and validating assertions correctly.

Consider further enhancing this process by integrating it with existing identity providers or a custom backend API, focusing on scalability and user experience.

Next Article: Enhance Security with Biometric Auth through the Web Authentication API in JavaScript

Previous Article: Authenticate Securely Using the Web Authentication API in JavaScript

Series: Web APIs – JavaScript Tutorials

JavaScript

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