DEV Community

Cover image for Access-First Authentication with QR + Device Signatures
Anton Minin Baranovskii
Anton Minin Baranovskii

Posted on

Access-First Authentication with QR + Device Signatures

Toqen.app is now live on the App Store.

This is an attempt to rethink authentication from an access-first perspective: instead of managing identities and credentials, focus on granting access in real time, per request.


Why rethink authentication

Most systems still rely on reusable credentials:

  • passwords
  • session tokens
  • API keys

These introduce predictable problems:

  • credential leaks
  • replay attacks
  • uncontrolled sharing

Even with MFA, the core model remains static.


Core idea

Each access request should be:

  • short-lived
  • single-use
  • bound to a device
  • cryptographically verifiable

Instead of storing secrets, the system verifies a signed challenge.


Flow

User opens login page

Server generates request

QR code is displayed

Mobile app scans QR

User confirms access

Device signs challenge

Server verifies signature

Access granted


QR format

QR does not contain secrets.

Example:

toqen://auth?request_id=91f2d&challenge=8fa92c1a&expires=1710000000

Properties:

  • expires in 30–60 seconds
  • single-use
  • cannot be replayed

Device model

On first launch:

  • device generates key pair
  • private key → stored in secure storage
  • public key → registered on server

Signing:

signature = sign(challenge, device_private_key)

Verification:

verify(signature, device_public_key)


Security properties

  • no reusable credentials
  • no secrets in QR
  • replay protection via TTL + single-use
  • device-bound authorization
  • server stores only public keys

Vault model

Sensitive data is encrypted client-side:

  • encrypted_vault
  • AES-256-GCM
  • vault_key stored in secure storage

Server never has decryption capability.


Where this fits

  • admin access
  • internal tools
  • high-risk operations
  • temporary access flows

Current status

  • iOS app is live on the App Store
  • Android version is in testing

Open for feedback

If you are working on authentication, security, or access control systems — feedback is welcome.

Contact: https://www.toqen.app/about#contacts

Android early access: https://forms.gle/f9FcbHyHJiajmFWV7


Building continues.

Top comments (0)