How can PHP be used to interact with the PayPal API to validate payment notifications and ensure data integrity?

To interact with the PayPal API to validate payment notifications and ensure data integrity, you can use PHP to verify the authenticity of the IPN (Instant Payment Notification) messages sent by PayPal. This involves verifying the message authenticity, checking the payment status, and ensuring the data integrity to prevent fraud. 

// Retrieve the IPN notification sent by PayPal
$raw_post_data = file_get_contents('php://input');

// Validate the IPN notification with PayPal
$ch = curl_init('https://www.paypal.com/cgi-bin/webscr');
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: application/x-www-form-urlencoded'));
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, 'cmd=_notify-validate&' . $raw_post_data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($ch);
curl_close($ch);

// Verify the response from PayPal
if ($response == 'VERIFIED') {
    // Process the payment notification and update your database
    // Ensure data integrity and prevent fraud
} else {
    // Log or handle the invalid IPN notification
}

Keywords

PHP PayPal API payment notifications data integrity validation

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