(PHP Extension) Adyen HMAC Signature Calculation for Hosted Payment Pages

Demonstrates how to do the HMAC Signature Calculation for a hosted payment page (HPP) in Adyen.

For a C# ASP.NET Razor Pages example showing the HTML Form with HMAC signature code, see Adyen HMAC Signature Calculation in C#

For more information, see https://docs.adyen.com/classic-integration/hosted-payment-pages/hmac-signature-calculation/

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<?php

// The version number (9_5_0) should match version of the Chilkat extension used, omitting the micro-version number.
// For example, if using Chilkat v9.5.0.48, then include as shown here:
include("chilkat_9_5_0.php");

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

$strHtml = '<table class=\'od\'><tr><th>Description</th><th>Quantity</th><th>Amount</th></tr><tr><td>1 Digital Camera</td><td class=\'r\'>1</td><td class=\'r\'>100 GBP</td></tr><tr><td class=\'b\'>Total</td><td class=\'r\'></td><td class=\'b r\'>100.00 GBP</td></tr></table>';

$gzip = new CkGzip();
$gzOrderData = $gzip->compressStringENC($strHtml,'utf-8','base64');

$xml = new CkXml();
$xml->put_Tag('keyValuePairs');

$xml->NewChild2('orderData',$gzOrderData);

// required, The payment deadline; the payment needs to occur within the specified time value.
$sessionValidity = '2019-08-11T10:30:00Z';
$xml->NewChild2('sessionValidity',$sessionValidity);

// optional.  Normally we'll let Adyen automatically know the country based on the IP address.
// By default, the payment methods offered to a shopper are filtered based on the country the shopper's IP address is mapped to. 
// In this way, shoppers are not offered payment methods that are not available in the country they are carrying out the transaction from. 
// This IP-to-country mapping is not 100% accurate, so if you have already established the country of the shopper, you can set it explicitly 
// in the countryCode parameter.
$countryCode = 'GB';
$xml->NewChild2('countryCode',$countryCode);

// optional
$shopperLocale = 'en_GB';
// If not specified, the locale preference is set to en_GB   by default.
// When it is not necessary to include the country-specific part, use only the language code.
// For example: it instead of it_IT to set the locale preferences to Italian.
$xml->NewChild2('shopperLocale',$shopperLocale);

// required, A reference to uniquely identify the payment. This reference is used in all communication with you about the payment status. 
// We recommend using a unique value per payment; however, it is not a requirement. If you need to provide multiple references for a transaction, 
// you can enter them in this field. Separate each reference value with a hyphen character ("-"). This field has a length restriction: 
// you can enter max. 80 characters.
$merchantReference = 'paymentTest1234';
$xml->NewChild2('merchantReference',$merchantReference);

// required, The merchant account identifier you want to process the (transaction) request with.
$merchantAccount = 'ChilkatSoftwareIncCOM';
$xml->NewChild2('merchantAccount',$merchantAccount);

// required.  10000 for $100.00
$paymentAmount = '10000';
$xml->NewChild2('paymentAmount',$paymentAmount);

// required, The three-character ISO currency code
$currencyCode = 'GBP';
$xml->NewChild2('currencyCode',$currencyCode);

// required.
$skinCode = 'S7uWsvfB';
$xml->NewChild2('skinCode',$skinCode);

// optional, A unique identifier for the shopper, for example, a customer ID.
// We recommend providing this information, as it is used in velocity fraud checks. It is also the key in recurring payments.
// This field is mandatory in recurring payments.  
$shopperReference = 'somebody@example.com';
$xml->NewChild2('shopperReference',$shopperReference);

// optional
$shopperEmail = 'somebody@example.com';
$xml->NewChild2('shopperEmail',$shopperEmail);

// optional, An integer value that adds up to the normal fraud score.
// The value can be either a positive or negative integer.
$xml->NewChild2('offset','0');

// Apparently this is a required field.
$shipBeforeDate = '2019-06-04';
$xml->NewChild2('shipBeforeDate',$shipBeforeDate);

$xml->SortByTag(true);

// Encode...
//  "\" (backslash) as "\\"
//  ":" (colon) as "\:"

$sbTags = new CkStringBuilder();
$sbValues = new CkStringBuilder();

$sbContent = new CkStringBuilder();
$n = $xml->get_NumChildren();
$i = 0;
while ($i < $n) {
    if ($i > 0) {
        $sbTags->Append(':');
        $sbValues->Append(':');
    }

    $xml->GetChild2($i);
    $sbTags->Append($xml->tag());

    $sbContent->SetString($xml->content());
    $numReplaced = $sbContent->Replace('\\','\\\\');
    $numReplaced = $sbContent->Replace(':','\\:');
    $sbValues->AppendSb($sbContent);
    $xml->GetParent2();

    $i = $i + 1;
}

$sbSigningStr = new CkStringBuilder();
$sbSigningStr->AppendSb($sbTags);
$sbSigningStr->Append(':');
$sbSigningStr->AppendSb($sbValues);

$crypt = new CkCrypt2();
$crypt->put_HashAlgorithm('sha256');
$crypt->put_MacAlgorithm('hmac');

$hmacKey = '934D1E806DDD99595EB430076FD7F8E4D12D0A3F51243A4C0C3897703118E739';
$crypt->SetMacKeyEncoded($hmacKey,'hex');

$crypt->put_EncodingMode('base64');
$merchantSig = $crypt->hmacStringENC($sbSigningStr->getAsString());

print $merchantSig . "\n";

?>