> ## Documentation Index
> Fetch the complete documentation index at: https://docs.authsignal.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Palm Biometrics & Verification Re-authentication

> An overview on how to integrate verification re-authentication use cases

## Verifying users for re-authentication

Authsignal's palm biometrics solution supports a wide range of use cases, which generally fall into two main categories or 'modes'.

<CardGroup cols={2}>
  <Card title="Payment" icon="credit-card" iconType="light" href="/api-reference/terminal-api/overview">
    Process payments at point of sale with an authorized payment amount
  </Card>

  <Card title="Access Control" icon="door-open" iconType="light">
    Use cases that involve access control style logic. Automatic gates, age verification, event ticketing
  </Card>
</CardGroup>

<Frame caption="Re-authentication Verification use cases">
  <img src="https://mintcdn.com/authsignal-23/o0kRW78VfDNgNDjk/images/docs/palm-biometrics/verification-use-cases.png?fit=max&auto=format&n=o0kRW78VfDNgNDjk&q=85&s=4ca675cd9bcaad6ab249b0cc38f4935e" alt="Re-authentication Verification use cases" width="1552" height="800" data-path="images/docs/palm-biometrics/verification-use-cases.png" />
</Frame>

# Re-authentication sequence

```mermaid theme={null}
sequenceDiagram
    participant U as User
    participant T as Android Terminal
    participant A as Authsignal
    participant W as Your backend webhook end-point
    U->>T: Presents palm to terminal device
    Note over T: Palm biometric template is captured
    T->>A: Palm biometric template is sent
    Note over A: Palm biometric is matched to an enrolled user
    A->>W: Palm Biometrics Webhook Verification Event
    Note over W: Perform decision and business logic
    W->>A: Respond with decision and custom messaging
    A->>T: Return wth decision <br />e.g. Payment success
    Note over T: Display error or success message <br /> optionally turn on relay switch
```

# Webhooks

<Note>
  [Palm biometrics decision webhook event schema documentation](/palm-biometrics/webhooks)
</Note>