What changes are required in the backend to use passkeys?

Implementing passkey-based login involves significant updates to backend logic to ensure secure and seamless authentication. Here’s what needs to be done:

• Add a backend component to handle WebAuthn operations for passkey registration and authentication.
• Use compatible libraries or frameworks, such as:
  • Node.js (e.g., @simplewebauthn/server)
  • Java (e.g., webauthn-server-core)
  • .NET (e.g., Fido2NetLib)

• Modify the authentication logic to:
  • Validate passkey credentials during login using the WebAuthn protocol.
  • Differentiate between passkey-based login and other authentication methods.
• Implement fallback options for users without passkeys (e.g., passwords or OTPs).

• Store the public key, credential ID, and user handle securely in your database.
• Ensure compliance with data protection regulations, such as GDPR or CCPA.

• Extend the user table to include passkey-related fields, such as:
  • Public key
  • Credential ID
  • User handle
  • Attestation data (optional)

• Support cross-device authentication by ensuring passkey credentials are not device-bound unless explicitly required.
• Enable cross-platform syncing for passkeys stored in platform authenticator clouds (e.g., iCloud Keychain, Google Password Manager).

Validate backend functionality with various scenarios:

• Passkey creation
• Authentication
• Error handling (e.g., invalid credentials or missing keys)

These backend changes ensure a secure and scalable implementation of passkey-based login, aligning with WebAuthn standards and best practices.