{
        withdraw_type: 'uah',
        amount: 100.0,
        gateway: 'default',
        withdraw_to: '4111111111111111' // CC number
    }

$response_data['request_data'] = [
    'withdraw_type' => 'btc',
    'amount' => $amount,
    'withdrawall' => true,
    'address' => $address,
];


$body_string_arr = [];

foreach ($response_data['request_data'] as $key => $value) {
    $body_string_arr[] = $key . '=' . $value;
}

$body_string = http_build_query($request_data);

$url = "https://api.kuna.io/v3/auth/withdraw";
$nounce = round(microtime(true) * 1000);

$signature = '/v3/auth/withdraw' . $nounce . $body_string;

$sig = hash_hmac('SHA384', $signature, $kuna_secret_key);


$headers = [
    'kun-nonce: ' . $nounce,
    'kun-apikey: ' . $kuna_api_key,
    'kun-signature: ' . $sig,
];

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);

curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POSTFIELDS, $body_string);


$res = curl_exec($ch);
curl_close($ch);

$res_array = json_decode($res, TRUE);

[
    {
        "status": "awaiting_confirmation",
        "message": "Your withdrawal request has been successfully submitted.",
        "withdrawal_id": 259267,
        "amount": 100.0
    }
]