> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/understand-cdcvm/device-unlock-method-update-scenarios.md).

# Device unlock method update scenarios

### Overview

This page explains how changes to the device unlock method affect CDCVM behavior.

The behavior depends on the CDCVM policy configured during NFC Wallet SDK initialization:

* `.biometricOnly`
* `.userPresence`

For setup details, see [NFC Wallet SDK initialization](/nfc-wallet-sdk-ios/get-started/configuration/3.-initialization.md#cardholder-verification-method) and [Understand CDCVM](/nfc-wallet-sdk-ios/implement-nfc-wallet/make-payments/understand-cdcvm.md).

### Scenarios

#### Scenarios for biometrics only (`.biometricOnly`)

<table data-full-width="true"><thead><tr><th>Device state change</th><th>iOS</th><th>NFC Wallet SDK</th><th>Digital wallet application</th></tr></thead><tbody><tr><td>End user disables the device lock screen. For example, biometrics are not enrolled and passcode is turned off.</td><td>Invalidates the key material in the keychain.</td><td>Detects that the key material is invalid when accessing the keychain.</td><td>Wipes local data and throws <code>ContactlessPaymentSession.Error.authenticationKeyInvalidated(error)</code>. Reinitialize the SDK. See <a href="/pages/aaZvcD4kfwI0oUryoCdX#tsh-pay-sdk-initialisation">NFC Wallet SDK initialization</a>.</td></tr><tr><td>End user disables the passcode, then re-enables it and re-enrolls biometrics.</td><td>Invalidates the key material in the keychain.</td><td>Detects that the key material is invalid when accessing the keychain.</td><td>Wipes local data and throws <code>ContactlessPaymentSession.Error.authenticationKeyInvalidated(error)</code>. Reinitialize the SDK. See <a href="/pages/aaZvcD4kfwI0oUryoCdX#tsh-pay-sdk-initialisation">NFC Wallet SDK initialization</a>.</td></tr><tr><td>End user changes the passcode while biometrics remain enrolled.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr><tr><td>End user keeps a passcode but removes all biometrics.</td><td>No action.</td><td>Detects that biometrics were removed.</td><td>Throws <code>ContactlessPaymentSession.Error.biometricNotEnrolled</code>.</td></tr><tr><td>End user keeps a passcode and enrolls new biometrics.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr></tbody></table>

#### Scenarios for user presence (`.userPresence`)

<table data-full-width="true"><thead><tr><th>Device state change</th><th>iOS</th><th>NFC Wallet SDK</th><th>Digital wallet application</th></tr></thead><tbody><tr><td>End user disables the device lock screen. For example, biometrics are not enrolled and passcode is turned off.</td><td>Invalidates the key material in the keychain.</td><td>Detects that the key material is invalid when accessing the keychain.</td><td>Wipes local data and throws <code>ContactlessPaymentSession.Error.authenticationKeyInvalidated(error)</code>. Reinitialize the SDK. See <a href="/pages/aaZvcD4kfwI0oUryoCdX#tsh-pay-sdk-initialisation">NFC Wallet SDK initialization</a>.</td></tr><tr><td>End user disables the passcode, then enables it again and enrolls biometrics again.</td><td>Invalidates the key material in the keychain.</td><td>Detects that the key material is invalid when accessing the keychain.</td><td>Wipes local data and throws <code>ContactlessPaymentSession.Error.authenticationKeyInvalidated(error)</code>. Reinitialize the SDK. See <a href="/pages/aaZvcD4kfwI0oUryoCdX#tsh-pay-sdk-initialisation">NFC Wallet SDK initialization</a>.</td></tr><tr><td>End user changes the passcode while biometrics remain enrolled.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr><tr><td>End user changes the passcode when no biometrics are enrolled.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr><tr><td>End user keeps a passcode but removes all biometrics.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr><tr><td>End user keeps a passcode and enrolls new biometrics.</td><td>No action.</td><td>No action.</td><td>No action.</td></tr></tbody></table>


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