# Pre-payment validation check

In case of exchange payment, the merchant can check a few validations before initiating a payment ex:

1. Insufficient Balance
2. The deposit address is not whitelisted
3. Password is required
4. etc

This API is NOT a core element of the payment flow. However, this helps to make a user-friendly payment solution.

The validation messages vary from exchange to exchange, but the API returns the same object with a different code that needs to handle at the merchant website.

Example:

1. OKcoin needs the deposit address for the whitelist, so this API checks whether or not the user has already whitelisted this address. In the API response, if the key "showWhitelistElement: true" means the deposit address is not whitelisted and merchant website should display the customer error.
2. A shopper's password is needed to withdraw the fund. If API returns a key "password: true," the shopper didn't provide the password, and the merchant's website should display a message to enter the password.

This API accepts the request payload in an encrypted format. The encryption algo is <*algo\_name> and encryption key is \<client\_*&#x73;ecret>.

```
// The sample request payload that needs to encrypt
{
  "clientId": "merchantid",
  "assets": "Selected exchange currency",
  "cart": "cart array",
  "offerId": "Order_id",
  "confirmation": "true",
  "nativeAmount": "cart amount in usd"
}

// clientId: The RKFL merchant identifier
// assets: Selected exchange currency (BTC/ETH)
// cart: cart array [{},{}]
// offerId: merchant unique identifie
// confirmation: true/false, true if shopper accept term and condition
// nativeAmount: cart total amount in USD

// The key "data" should generate from the below way.
export const data = async (toEncrypt, publicKey) => {
  const buffer = Buffer.from(toEncrypt);
  const encrypted = crypto.publicEncrypt(publicKey, buffer);
  return encrypted.toString('base64');
};
```

<mark style="color:green;">`POST`</mark> `/exchanges/payment-validate/{exchange_name}`

The value of exchange\_name are "coinbase/okcoin/kraken/gemini/binanceus"

#### Headers

| Name                                            | Type   | Description                     |
| ----------------------------------------------- | ------ | ------------------------------- |
| Authorization<mark style="color:red;">\*</mark> | String | "Bearer" + shopper access token |
| Content-Type                                    | String | application/json                |

#### Request Body

| Name                                   | Type   | Description      |
| -------------------------------------- | ------ | ---------------- |
| data<mark style="color:red;">\*</mark> | String | Encrypted string |

{% tabs %}
{% tab title="200: OK Success" %}

```javascript
{
    "ok": true,
    "result": {
        "receiverAddress": "3Jmmku8JTHP2YsqNZ3RuhZdburbdHMtSjT",
        "receiverMemo": null,
        "amount": 0,
        "currency": "BTC",
        "fee": 0.00000526,
        "password": false,
        "showWhitelistElement": false,
        "exchange": "coinbase",
        "nativeAmount": 5,
        "newRate": {
            "percentRate": 0,
            "newFiatRate": 0
        }
    }
}
```

{% endtab %}
{% endtabs %}