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

# Cardholder Authentication Application

Creates or updates a cardholder KYC authentication application.

## Request Headers

<ParamField header="Api-Key" type="string" required placeholder="your_api_key">
  apiKey (merchant credential, bound to IP whitelist)
</ParamField>

<ParamField header="Timestamp" type="string" required>
  Unix timestamp in milliseconds. The deviation from the server time must be within 60 seconds, and future timestamps are not accepted.
</ParamField>

<ParamField header="Access-Token" type="string" required placeholder="your_access_token">
  Login token (required for all interfaces except Get Token).
</ParamField>

<ParamField header="Content-Type" type="string" default="application/json">
  Fixed to `application/json`
</ParamField>

## Request Body

<ParamField body="cardholder_no" type="string">
  Cardholder order number (**required when updating authentication**).
</ParamField>

<ParamField body="cardholder_unique_no" type="string" required>
  Merchant-side unique cardholder number.
</ParamField>

<ParamField body="sumsub_share_token" type="string" required placeholder="your_sumsub_share_token">
  Sumsub shareToken.
</ParamField>

<Note>
  * **Create new**: Do not pass `cardholder_no`; provide `cardholder_unique_no` + `sumsub_share_token`.
  * **Update authentication**: Pass `cardholder_no`, and `cardholder_unique_no` must match the record on the platform.
</Note>

## Response Parameters

<ResponseField name="code" type="number">
  Response status code. `0` indicates success.
</ResponseField>

<ResponseField name="msg" type="string">
  Response message.
</ResponseField>

<ResponseField name="data" type="object">
  Response data.

  <Expandable title="data">
    <ResponseField name="cardholder_no" type="string">Cardholder order number</ResponseField>
    <ResponseField name="cardholder_unique_no" type="string">Merchant-side unique cardholder number</ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash Request theme={null}
  curl --request POST \
    --url https://sandbox-openplatform.keysecure.io/open-api/v1/cardholder/apply \
    --header 'Content-Type: application/json' \
    --header 'Api-Key: your_api_key' \
    --header 'Timestamp: 1716307200000' \
    --header 'Access-Token: your_access_token' \
    --data '{
      "cardholder_no": "",
      "cardholder_unique_no": "MERCHANT_USER_001",
      "sumsub_share_token": "your_sumsub_share_token"
    }'
  ```
</RequestExample>

<ResponseExample>
  ```json Response theme={null}
  {
    "code": 0,
    "msg": "Success",
    "data": {
      "cardholder_no": "",
      "cardholder_unique_no": ""
    }
  }
  ```
</ResponseExample>