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

# Strong customer authentication

> Submit Strong Customer Authentication attestations with custodial transfers.

Strong Customer Authentication (SCA) requires authentication using at least two independent factors: something the user knows, has, or is. View [Stripe's SCA overview](https://docs.stripe.com/strong-customer-authentication) for regulatory background.

Privy custodial wallets support sending SCA attestations for Transfer Actions. Your app handles customer authentication, and Privy forwards the resulting attestation to Bridge for compliance checks.

## Sending SCA attestations

To provide an SCA attestation, include this object in Privy's `/v1/wallets/[wallet_id]/transfer` request:

```json theme={"system"}
{
  "custody_options": {
    "initiation": {
      "channel": "other_mobile_payment",
      "subchannel": "remote",
      "attestations": {
        "sca": {
          "outcome": "sca_used"
        }
      }
    }
  }
}
```

Set `channel` and `subchannel` to match how the payment was initiated. For an eligible exemption or non-applicability reason, use the corresponding `outcome` instead of `sca_used`.

View the [transfer parameters](/wallets/custodial-wallets/sending-funds#parameters) for supported fields and optional authentication factor metadata.