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This class will use the functionality you implemented in the previous two exercises
to ensure that its data will be stored securely in the database.
Exercise: Implementing the SecureCard Class
1. Create a new file named secure_card.php in the business folder, and add the following code to it:
// Represents a credit card
class SecureCard
{
// Private members containing credit card's details
private $_mIsDecrypted = false;
private $_mIsEncrypted = false;
private $_mCardHolder;
private $_mCardNumber;
private $_mIssueDate;
private $_mExpiryDate;
private $_mIssueNumber;
private $_mCardType;
private $_mEncryptedData;
private $_mXmlCardData;
// Class constructor
public function __construct()
{
// Nothing here
}
// Decrypt data
public function LoadEncryptedDataAndDecrypt($newEncryptedData)
{
$this->_mEncryptedData = $newEncryptedData;
$this->DecryptData();
}
// Encrypt data
public function LoadPlainDataAndEncrypt($newCardHolder, $newCardNumber,
$newIssueDate, $newExpiryDate,
$newIssueNumber, $newCardType)
{
$this->_mCardHolder = $newCardHolder;
$this->_mCardNumber = $newCardNumber;
$this->_mIssueDate = $newIssueDate;
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$this->_mExpiryDate = $newExpiryDate;
$this->_mIssueNumber = $newIssueNumber;
$this->_mCardType = $newCardType;
$this->EncryptData();
}
// Create XML with credit card information
private function CreateXml()
{
// Encode card details as XML document
$xml_card_data = &$this->_mXmlCardData;
$xml_card_data = new DOMDocument();
$document_root = $xml_card_data->createElement('CardDetails');
$child = $xml_card_data->createElement('CardHolder');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mCardHolder);
$value = $child->appendChild($value);
$child = $xml_card_data->createElement('CardNumber');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mCardNumber);
$value = $child->appendChild($value);
$child = $xml_card_data->createElement('IssueDate');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mIssueDate);
$value = $child->appendChild($value);
$child = $xml_card_data->createElement('ExpiryDate');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mExpiryDate);
$value = $child->appendChild($value);
$child = $xml_card_data->createElement('IssueNumber');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mIssueNumber);
$value = $child->appendChild($value);
$child = $xml_card_data->createElement('CardType');
$child = $document_root->appendChild($child);
$value = $xml_card_data->createTextNode($this->_mCardType);
$value = $child->appendChild($value);
$document_root = $xml_card_data->appendChild($document_root);
}
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// Extract information from XML credit card data
private function ExtractXml($decryptedData)
{
$xml = simplexml_load_string($decryptedData);
$this->_mCardHolder = (string) $xml->CardHolder;
$this->_mCardNumber = (string) $xml->CardNumber;
$this->_mIssueDate = (string) $xml->IssueDate;
$this->_mExpiryDate = (string) $xml->ExpiryDate;
$this->_mIssueNumber = (string) $xml->IssueNumber;
$this->_mCardType = (string) $xml->CardType;
}
// Encrypts the XML credit card data
private function EncryptData()
{
// Put data into XML doc
$this->CreateXml();
// Encrypt data
$this->_mEncryptedData =
SymmetricCrypt::Encrypt($this->_mXmlCardData->saveXML());
// Set encrypted flag
$this->_mIsEncrypted = true;
}
// Decrypts XML credit card data
private function DecryptData()
{
// Decrypt data
$decrypted_data = SymmetricCrypt::Decrypt($this->_mEncryptedData);
// Extract data from XML
$this->ExtractXml($decrypted_data);
// Set decrypted flag
$this->_mIsDecrypted = true;
}
public function __get($name)
{
if ($name == 'EncryptedData')
{
if ($this->_mIsEncrypted)
return $this->_mEncryptedData;
else
throw new Exception('Data not encrypted');
}
CHAPTER 16 ?–  MANAGING CUSTOMER DETAILS 492
elseif ($name == 'CardNumberX')
{
if ($this->_mIsDecrypted)
return 'XXXX-XXXX-XXXX-' .


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