> For the complete documentation index, see [llms.txt](https://docs.caf.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.caf.io/caf-sdk/android/standalone-modules/cafsmartauth/start-sdk.md).

# Start Smart Authentication

## Calling verifyPolicy

To start the liveness verification, use the `startSDK()` method with the user's document ID, your account mobile token and `CafVerifyPolicyListener` interface.

| Parameter     | Type                                                                                                             | Description                                                                                                                                                                                                                   | Required |
| ------------- | ---------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :------: |
| `mobileToken` | String                                                                                                           | Usage token associated with your CAF account                                                                                                                                                                                  |     ✅    |
| `personId`    | String                                                                                                           | Identifier of the user who will perform the face liveness verification. It's recommended to use the user's identification document in this field, such as their CPF (Brazilian document ID), but it could be any other value. |     ✅    |
| `listener`    | [CafVerifyPolicyListener](/caf-sdk/android/standalone-modules/cafsmartauth/lifecycle.md#cafverifypolicylistener) | Interface which handles key events during the SDK's liveness detection process:                                                                                                                                               |     ✅    |

### Example

```kotlin
    private fun startSdk() {
        smartAuth.verifyPolicy(
            "userDocument",
            "myPolicyId",
            setupListener()
        )
    }

    private fun setupListener() = object : CafVerifyPolicyListener {
        override fun onSuccess(
            isAuthorized: Boolean,
            attemptId: String?,
            attestation: String?
        ) {
            println("CafVerifyPolicyListener.onSuccess isAuthorized: $isAuthorized")
            println("CafVerifyPolicyListener.onSuccess attemptId: $attemptId")
            println("CafVerifyPolicyListener.onSuccess attestation: $attestation")
        }

        override fun onPending(isAuthorized: Boolean, attestation: String) {
            println("CafVerifyPolicyListener.onPending isAuthorized: $isAuthorized")
            println("CafVerifyPolicyListener.onPending attestation: $attestation")
        }

        override fun onError(failure: CafFailure) {
            println("CafVerifyPolicyListener.onError failure: ${failure.message}")
        }

        override fun onCancel() {
            println("CafVerifyPolicyListener.onCancel")
        }

        override fun onLoading() {
            println("CafVerifyPolicyListener.onLoading")
        }

        override fun onLoaded() {
            println("CafVerifyPolicyListener.onLoaded")
        }
    }
```


---

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