php openssl_encrypt returns 2648 bytes

Question

I have some C# Code used to encrypt text and I make the PHP equivalent of it. The returned string from C# method is 1560 bytes, but my PHP method returns 2648 bytes and I didn't know why although I'm using the same Encryption Criteria for AES-256 bit as C# App which are:

Block Mode: CBC Padding: PKCS7 Block Size: 16 bytes Encryption Key Size: 32 bytes Initialization Vector Size: 16 bytes

C# Code:

public string AES256Encrypt(string toEncrypt, out string key)
{
try
            {
                AesManaged AESManaged = new AesManaged();

                byte[] AESKey = AESManaged.Key;
                byte[] AESIV = AESManaged.IV;
                byte[] encryptedData = null;

                ICryptoTransform cryptoTransform = AESManaged.CreateEncryptor(AESKey, AESIV);

                using (MemoryStream memoryStream = new MemoryStream())
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, cryptoTransform, CryptoStreamMode.Write))
                    {
                        using (StreamWriter streamWriter = new StreamWriter(cryptoStream))
                        {
                            streamWriter.Write(toEncrypt);
                        }

                        encryptedData = memoryStream.ToArray();
                    }
                }

                byte[] keyBytes = new byte[AESKey.Length + AESIV.Length];

                Array.Copy(AESKey, 0, keyBytes, 0, AESKey.Length);
                Array.Copy(AESIV, 0, keyBytes, AESKey.Length, AESIV.Length);

                key = Convert.ToBase64String(keyBytes);

                return Convert.ToBase64String(encryptedData);

            }
            catch (Exception ex)
            {
                key = null;
                return null;
            }
}

and my PHP Code is:

public function AESencrypt($plaintext, &$macKey)
{
    $key = random_bytes(32);
    //$key = bin2hex(openssl_random_pseudo_bytes(32));
    $keyArr = unpack('C*', $key);
    $iv = random_bytes(16);
    //$iv = bin2hex(openssl_random_pseudo_bytes(16)) ;
    $ivArr = unpack('C*', $iv);
    $encryptedData = openssl_encrypt(
        $plaintext,
        'AES-256-CBC',
        $key,
        OPENSSL_RAW_DATA,
        $iv
    );
    //        while ($encryptedData = openssl_error_string())
    //            echo $encryptedData . "<br />\n";exit;
    $keyBytes = array();
    //clone the $keyArr to the keyBytes Array
    foreach ($keyArr as $key => $item) {
        $keyBytes[$key] = $item;
    }
    //clone the $ivArr to the keyBytes Array from index 32 to 48
    foreach ($ivArr as $key => $item) {
        $keyBytes[$key+32] = $item;
    }
    $string = implode(array_map("chr", $keyBytes));
    $returned = 
        array(
        'encrypted' => base64_encode($encryptedData),
        'randomSecret' => base64_encode($string),
    );
    //print '<pre>'; print_r($returned);exit;
    return $returned;
}

and this is the object passed to be encrypted for the two applications

<?xml version="1.0" encoding="utf-16"?>
<PaymentRequestInitiationReq 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <Sender>
        <Id>029</Id>
        <Name>Biller</Name>
        <RandomValue>54b86c4e2df948659b186571a924e516</RandomValue>
        <Password>XG94dze10PfZXrfJ7pDnuyR8MBi2SBQq24r6NLjAN0kz3Ay/OoOahqrfHI0n0azg+GkIqvEdK0ddgKip6AAd5TN14MmGL0hgc99/2JFkSrEL8brylG8MxiZIqTKoEb7hOV84V+tHcolbUNux0o1OOGrD4lgrh3BMV/hddwlwb97sXguadOPEdVVCLCEN3qyo15vGtmgTR1dcaWj1Pj3KIEeQvJifA4FjTSqFLEwLDHMnKZEjjkjDmNGc7pYsWxYP8dm6FAiUbYB+G8PsiFhiHsYxNygsYB/dTn2dY7vgV4iBUD9EnNkbb6dUFIZJ0hCYllKWhONWxKwJ4oK3MGlR3g==</Password>
    </Sender>
    <SettlementAmounts>
        <SettlementAmounts>
            <SettlementAccountCode>1073</SettlementAccountCode>
            <SettlementAmountsDescription />
            <Amount>25</Amount>
        </SettlementAmounts>
    </SettlementAmounts>
    <SenderRequestNumber>01a19e11f5bf4349</SenderRequestNumber>
    <SenderInvoiceNumber />
    <ServiceCode>140</ServiceCode>
    <RequestInitiationDescription />
    <Currency>818</Currency>
    <IP>::1</IP>
    <PaymentMechanism>
        <Type>NotSet</Type>
        <MechanismType>NotSet</MechanismType>
        <Channel />
    </PaymentMechanism>
    <ExpiryDate>2019-07-17</ExpiryDate>
    <PaymentConfirmationUrl>http://127.0.0.1/agri360/index.php?route=checkout/success</PaymentConfirmationUrl>
    <PaymentConfirmationRedirectUrl>http://127.0.0.1/agri360/index.php?route=checkout/success</PaymentConfirmationRedirectUrl>
    <UserUniqueIdentifier>1234456778</UserUniqueIdentifier>
</PaymentRequestInitiationReq>

Please can anyone help me and show me why this is happening?

Ehab Adel Ehab Adel · Accepted Answer · 2019-07-22T14:34:40

Finally, I have solved it. C# deals with that XML Object string not the same as PHP, So I have made the PHP-side string on one line and the "Encrypted Object" Length became the same.

php openssl_encrypt returns 2648 bytes

1 Answers