passkey - dwilson2547/wiki_demo GitHub Wiki

Passkeys are a modern, passwordless authentication technology designed to replace traditional passwords and multi-factor authentication (MFA) methods like SMS codes or authenticator apps. They leverage public-key cryptography and biometric authentication (e.g., fingerprint or facial recognition) to provide a more secure, convenient, and phishing-resistant way to log in to apps and websites.

Here’s a detailed explanation of passkeys:

1. What Are Passkeys?

  • Passkeys are digital credentials tied to a user account and a specific device (e.g., smartphone, laptop).
  • They use public-key cryptography to authenticate users without requiring passwords.
  • Passkeys are phishing-resistant because they rely on cryptographic proofs rather than shared secrets.

2. How Passkeys Work

A. Core Principles

  • Public-Key Cryptography: Each passkey consists of a public key (stored by the website or app) and a private key (stored securely on the user’s device).
  • Biometric or PIN Authentication: The private key is unlocked using the device’s built-in authentication (e.g., fingerprint, Face ID, or PIN).
  • No Shared Secrets: Unlike passwords, the private key never leaves the device, making it immune to phishing and server breaches.

B. Registration (Creating a Passkey)

  1. User Initiates Registration: The user signs up for a service (e.g., a website or app) and chooses to create a passkey.
  2. Device Generates Key Pair: The user’s device generates a public-private key pair.
  3. Public Key Sent to Server: The public key is sent to the service’s server and associated with the user’s account.
  4. Private Key Stored Securely: The private key is stored securely on the device (e.g., in the Secure Enclave on iPhones or Trusted Platform Module (TPM) on PCs).

C. Authentication (Logging In)

  1. User Initiates Login: The user attempts to log in to the service.
  2. Server Sends Challenge: The server sends a cryptographic challenge to the user’s device.
  3. Device Signs Challenge: The device uses the private key to sign the challenge, proving ownership of the public key.
  4. User Authenticates Locally: The user unlocks the private key using biometrics or a PIN.
  5. Device Sends Signed Response: The signed challenge is sent back to the server.
  6. Server Verifies Signature: The server verifies the signature using the stored public key. If valid, the user is authenticated.

3. Key Features of Passkeys

Feature Description
Passwordless Eliminates the need for passwords, reducing the risk of phishing and credential theft.
Phishing-Resistant Private keys never leave the device, making passkeys immune to phishing attacks.
Cross-Platform Passkeys sync across devices (e.g., iPhone, iPad, Mac) via iCloud Keychain or Google Password Manager.
Biometric Authentication Uses device-native biometrics (e.g., Face ID, Touch ID, or PIN) for user verification.
FIDO2 Standard Built on the FIDO2 and WebAuthn standards, ensuring broad compatibility.
No Shared Secrets Private keys are never transmitted or stored on servers, reducing the risk of breaches.

4. Technical Underpinnings

A. FIDO2 and WebAuthn

  • Passkeys are built on the FIDO2 standard, which includes:
    • WebAuthn: A web API that allows browsers to interact with authenticators (e.g., devices) for passwordless authentication.
    • CTAP (Client to Authenticator Protocol): Enables communication between devices (e.g., phones) and computers for authentication.

B. Public-Key Cryptography

  • Passkeys use asymmetric cryptography:
    • Public Key: Shared with the service and used to verify signatures.
    • Private Key: Stored securely on the device and used to sign challenges.

C. Device Security

  • Private keys are stored in hardware-secured modules (e.g., Secure Enclave on iPhones, TPM on PCs).
  • Access to private keys requires local authentication (e.g., biometrics or PIN).

5. Advantages of Passkeys

Advantage Description
Security Resistant to phishing, credential stuffing, and server breaches.
Convenience No need to remember or type passwords; authentication is fast and seamless.
User Experience Uses familiar device authentication methods (e.g., Face ID, Touch ID).
Cross-Device Sync Passkeys sync across devices via cloud services (e.g., iCloud, Google Password Manager).
Industry Support Backed by major tech companies (e.g., Apple, Google, Microsoft, and the FIDO Alliance).

6. How Passkeys Differ from Traditional Authentication

Feature Passkeys Traditional Authentication (Passwords, OTPs)
Authentication Method Biometrics or PIN. Passwords, SMS codes, or authenticator apps.
Phishing Resistance Yes (private keys never leave the device). No (passwords and OTPs can be phished).
User Experience Seamless and fast. Requires typing passwords or entering codes.
Server-Side Storage Only the public key is stored. Passwords or OTP secrets are stored, creating a risk of breaches.
Cross-Platform Support Yes (via FIDO2 and WebAuthn). Limited (e.g., SMS OTPs require phone connectivity).

7. Use Cases for Passkeys

A. Consumer Applications

  • Websites and Apps: Passkeys can replace passwords for logging into websites and apps (e.g., social media, banking).
  • E-Commerce: Secure and convenient checkout experiences.
  • Gaming: Passwordless login for gaming platforms.

B. Enterprise Applications

  • Employee Authentication: Secure access to corporate resources (e.g., VPNs, internal tools).
  • Single Sign-On (SSO): Integration with SSO providers for seamless authentication.

C. IoT and Devices

  • Smart Home Devices: Secure authentication for smart home apps.
  • Wearables: Passwordless login for wearables (e.g., smartwatches).

8. How to Implement Passkeys

A. For Developers

  1. Adopt WebAuthn: Use the WebAuthn API to enable passkey support in web apps.

    • Example JavaScript code for registration: 
      const publicKeyCredentialCreationOptions = {
  challenge: new Uint8Array([...]), // Server-generated challenge
  rp: { name: "Example App", id: "example.com" },
  user: { id: new Uint8Array([...]), name: "[email protected]", displayName: "User" },
  pubKeyCredParams: [{ type: "public-key", alg: -7 }], // ES256 algorithm
};
const credential = await navigator.credentials.create({ publicKey: publicKeyCredentialCreationOptions });
    • Example JavaScript code for authentication: 
      const publicKeyCredentialRequestOptions = {
  challenge: new Uint8Array([...]), // Server-generated challenge
  rpId: "example.com",
};
const assertion = await navigator.credentials.get({ publicKey: publicKeyCredentialRequestOptions });

  2. Server-Side Integration: Store public keys and verify signatures on the server.

    • Use libraries like WebAuthn4J (Java) or PyWebAuthn (Python) for server-side validation.

  3. Support Cross-Platform: Ensure compatibility with FIDO2 and CTAP for cross-device authentication.

B. For Users

  1. Create a Passkey: When prompted by a website or app, follow the device’s instructions to create a passkey (e.g., use Face ID or Touch ID).
  2. Use a Passkey: Authenticate using biometrics or PIN when logging in.

9. Security Considerations

A. Private Key Protection

  • Private keys are stored in hardware-secured modules (e.g., Secure Enclave, TPM), making them resistant to extraction.
  • Access to private keys requires local authentication (e.g., biometrics or PIN).

B. Phishing Resistance

  • Passkeys are phishing-resistant because the private key never leaves the device, and authentication is tied to the relying party (RP) ID (e.g., example.com).

C. Backup and Recovery

  • Passkeys can be synced across devices via cloud services (e.g., iCloud Keychain, Google Password Manager).
  • Users can recover passkeys by signing in to their cloud account on a new device.

D. Multi-Device Support

  • Passkeys support cross-device authentication (e.g., using a phone to authenticate on a laptop via Bluetooth or QR codes).

10. Industry Adoption

  • Apple: Introduced passkey support in iOS 16, macOS Ventura, and iPadOS 16.
  • Google: Added passkey support in Android 9+ and Chrome.
  • Microsoft: Supports passkeys in Windows 10/11 and Edge.
  • FIDO Alliance: Promotes passkeys as part of the FIDO2 standard.

11. Example: Using a Passkey

A. Registration

  1. A user visits example.com and selects "Create a Passkey".
  2. The website sends a challenge to the user’s device.
  3. The device prompts the user to authenticate (e.g., using Face ID).
  4. The device generates a key pair, sends the public key to the website, and stores the private key securely.

B. Authentication

  1. The user returns to example.com and selects "Log In with Passkey".
  2. The website sends a challenge to the user’s device.
  3. The device prompts the user to authenticate (e.g., using Face ID).
  4. The device signs the challenge with the private key and sends the signed response to the website.
  5. The website verifies the signature using the public key and logs the user in.

12. Challenges and Limitations

Challenge Description
Legacy Systems Older devices or browsers may not support passkeys.
User Education Users may be unfamiliar with passkeys and require guidance.
Cross-Platform Sync Syncing passkeys across ecosystems (e.g., Apple to Android) can be challenging.
Backup Dependencies Passkeys rely on cloud services (e.g., iCloud, Google) for backup and recovery.

13. Future of Passkeys

  • Wider Adoption: More websites and apps are expected to adopt passkeys as the default authentication method.
  • Standardization: Continued development of FIDO2 and WebAuthn standards.
  • Interoperability: Improved cross-platform and cross-ecosystem support.

14. Summary Table: Passkeys

Aspect Description
Purpose Replace passwords with a secure, passwordless authentication method.
Technology Public-key cryptography, FIDO2, WebAuthn.
Authentication Method Biometrics (e.g., Face ID, Touch ID) or PIN.
Security Phishing-resistant, no shared secrets, hardware-secured private keys.
User Experience Seamless and fast; no need to remember passwords.
Cross-Platform Syncs across devices via cloud services (e.g., iCloud, Google Password Manager).
Industry Support Backed by Apple, Google, Microsoft, and the FIDO Alliance.

Why Are Passkeys Important?

Passkeys represent a major leap forward in authentication security and usability. By eliminating passwords and leveraging public-key cryptography and biometric authentication, they provide a secure, convenient, and phishing-resistant way to log in to apps and websites.

Would you like to explore how to implement passkeys in a web app, how passkeys compare to hardware security keys, or how to migrate from passwords to passkeys?

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