(Unicode C++) 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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#include <CkGzipW.h>
#include <CkXmlW.h>
#include <CkStringBuilderW.h>
#include <CkCrypt2W.h>

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

    bool success;

    const wchar_t *strHtml = L"<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>";

    CkGzipW gzip;
    const wchar_t *gzOrderData = gzip.compressStringENC(strHtml,L"utf-8",L"base64");

    CkXmlW xml;
    xml.put_Tag(L"keyValuePairs");

    xml.NewChild2(L"orderData",gzOrderData);

    // required, The payment deadline; the payment needs to occur within the specified time value.
    const wchar_t *sessionValidity = L"2019-08-11T10:30:00Z";
    xml.NewChild2(L"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.
    const wchar_t *countryCode = L"GB";
    xml.NewChild2(L"countryCode",countryCode);

    // optional
    const wchar_t *shopperLocale = L"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(L"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.
    const wchar_t *merchantReference = L"paymentTest1234";
    xml.NewChild2(L"merchantReference",merchantReference);

    // required, The merchant account identifier you want to process the (transaction) request with.
    const wchar_t *merchantAccount = L"ChilkatSoftwareIncCOM";
    xml.NewChild2(L"merchantAccount",merchantAccount);

    // required.  10000 for $100.00
    const wchar_t *paymentAmount = L"10000";
    xml.NewChild2(L"paymentAmount",paymentAmount);

    // required, The three-character ISO currency code
    const wchar_t *currencyCode = L"GBP";
    xml.NewChild2(L"currencyCode",currencyCode);

    // required.
    const wchar_t *skinCode = L"S7uWsvfB";
    xml.NewChild2(L"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.  
    const wchar_t *shopperReference = L"somebody@example.com";
    xml.NewChild2(L"shopperReference",shopperReference);

    // optional
    const wchar_t *shopperEmail = L"somebody@example.com";
    xml.NewChild2(L"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(L"offset",L"0");

    // Apparently this is a required field.
    const wchar_t *shipBeforeDate = L"2019-06-04";
    xml.NewChild2(L"shipBeforeDate",shipBeforeDate);

    xml.SortByTag(true);

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

    CkStringBuilderW sbTags;
    CkStringBuilderW sbValues;

    CkStringBuilderW sbContent;
    int n = xml.get_NumChildren();
    int i = 0;
    while (i < n) {
        if (i > 0) {
            sbTags.Append(L":");
            sbValues.Append(L":");
        }

        xml.GetChild2(i);
        sbTags.Append(xml.tag());

        sbContent.SetString(xml.content());
        int numReplaced = sbContent.Replace(L"\\",L"\\\\");
        numReplaced = sbContent.Replace(L":",L"\\:");
        sbValues.AppendSb(sbContent);
        xml.GetParent2();

        i = i + 1;
    }

    CkStringBuilderW sbSigningStr;
    sbSigningStr.AppendSb(sbTags);
    sbSigningStr.Append(L":");
    sbSigningStr.AppendSb(sbValues);

    CkCrypt2W crypt;
    crypt.put_HashAlgorithm(L"sha256");
    crypt.put_MacAlgorithm(L"hmac");

    const wchar_t *hmacKey = L"934D1E806DDD99595EB430076FD7F8E4D12D0A3F51243A4C0C3897703118E739";
    crypt.SetMacKeyEncoded(hmacKey,L"hex");

    crypt.put_EncodingMode(L"base64");
    const wchar_t *merchantSig = crypt.hmacStringENC(sbSigningStr.getAsString());

    wprintf(L"%s\n",merchantSig);
    }