(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 <C_CkGzip.h>
#include <C_CkXml.h>
#include <C_CkStringBuilder.h>
#include <C_CkCrypt2.h>

void ChilkatSample(void)
    {
    BOOL success;
    const char *strHtml;
    HCkGzip gzip;
    const char *gzOrderData;
    HCkXml xml;
    const char *sessionValidity;
    const char *countryCode;
    const char *shopperLocale;
    const char *merchantReference;
    const char *merchantAccount;
    const char *paymentAmount;
    const char *currencyCode;
    const char *skinCode;
    const char *shopperReference;
    const char *shopperEmail;
    const char *shipBeforeDate;
    HCkStringBuilder sbTags;
    HCkStringBuilder sbValues;
    HCkStringBuilder sbContent;
    int n;
    int i;
    int numReplaced;
    HCkStringBuilder sbSigningStr;
    HCkCrypt2 crypt;
    const char *hmacKey;
    const char *merchantSig;

    // 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 = CkGzip_Create();
    gzOrderData = CkGzip_compressStringENC(gzip,strHtml,"utf-8","base64");

    xml = CkXml_Create();
    CkXml_putTag(xml,"keyValuePairs");

    CkXml_NewChild2(xml,"orderData",gzOrderData);

    // required, The payment deadline; the payment needs to occur within the specified time value.
    sessionValidity = "2019-08-11T10:30:00Z";
    CkXml_NewChild2(xml,"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";
    CkXml_NewChild2(xml,"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.
    CkXml_NewChild2(xml,"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";
    CkXml_NewChild2(xml,"merchantReference",merchantReference);

    // required, The merchant account identifier you want to process the (transaction) request with.
    merchantAccount = "ChilkatSoftwareIncCOM";
    CkXml_NewChild2(xml,"merchantAccount",merchantAccount);

    // required.  10000 for $100.00
    paymentAmount = "10000";
    CkXml_NewChild2(xml,"paymentAmount",paymentAmount);

    // required, The three-character ISO currency code
    currencyCode = "GBP";
    CkXml_NewChild2(xml,"currencyCode",currencyCode);

    // required.
    skinCode = "S7uWsvfB";
    CkXml_NewChild2(xml,"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";
    CkXml_NewChild2(xml,"shopperReference",shopperReference);

    // optional
    shopperEmail = "somebody@example.com";
    CkXml_NewChild2(xml,"shopperEmail",shopperEmail);

    // optional, An integer value that adds up to the normal fraud score.
    // The value can be either a positive or negative integer.
    CkXml_NewChild2(xml,"offset","0");

    // Apparently this is a required field.
    shipBeforeDate = "2019-06-04";
    CkXml_NewChild2(xml,"shipBeforeDate",shipBeforeDate);

    CkXml_SortByTag(xml,TRUE);

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

    sbTags = CkStringBuilder_Create();
    sbValues = CkStringBuilder_Create();

    sbContent = CkStringBuilder_Create();
    n = CkXml_getNumChildren(xml);
    i = 0;
    while (i < n) {
        if (i > 0) {
            CkStringBuilder_Append(sbTags,":");
            CkStringBuilder_Append(sbValues,":");
        }

        CkXml_GetChild2(xml,i);
        CkStringBuilder_Append(sbTags,CkXml_tag(xml));

        CkStringBuilder_SetString(sbContent,CkXml_content(xml));
        numReplaced = CkStringBuilder_Replace(sbContent,"\\","\\\\");
        numReplaced = CkStringBuilder_Replace(sbContent,":","\\:");
        CkStringBuilder_AppendSb(sbValues,sbContent);
        CkXml_GetParent2(xml);

        i = i + 1;
    }

    sbSigningStr = CkStringBuilder_Create();
    CkStringBuilder_AppendSb(sbSigningStr,sbTags);
    CkStringBuilder_Append(sbSigningStr,":");
    CkStringBuilder_AppendSb(sbSigningStr,sbValues);

    crypt = CkCrypt2_Create();
    CkCrypt2_putHashAlgorithm(crypt,"sha256");
    CkCrypt2_putMacAlgorithm(crypt,"hmac");

    hmacKey = "934D1E806DDD99595EB430076FD7F8E4D12D0A3F51243A4C0C3897703118E739";
    CkCrypt2_SetMacKeyEncoded(crypt,hmacKey,"hex");

    CkCrypt2_putEncodingMode(crypt,"base64");
    merchantSig = CkCrypt2_hmacStringENC(crypt,CkStringBuilder_getAsString(sbSigningStr));

    printf("%s\n",merchantSig);


    CkGzip_Dispose(gzip);
    CkXml_Dispose(xml);
    CkStringBuilder_Dispose(sbTags);
    CkStringBuilder_Dispose(sbValues);
    CkStringBuilder_Dispose(sbContent);
    CkStringBuilder_Dispose(sbSigningStr);
    CkCrypt2_Dispose(crypt);

    }