(C++) Payeezy HMAC Computation

Demonstrates how to calculate the HMAC for a Payeezy REST request.

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#include <CkCrypt2.h>
#include <CkPrng.h>
#include <CkDateTime.h>
#include <CkStringBuilder.h>
#include <CkJsonObject.h>

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

    CkCrypt2 crypt;
    CkPrng prng;
    bool success;

    // An API key such as y6pWAJNyJyjGv66IsVuWnklkKUPFbb0a
    const char *apiKey = "my_api_key";
    // An API secret such as 86fbae7030253af3cd15faef2a1f4b67353e41fb6799f576b5093ae52901e6f7
    const char *apiSecret = "my_api_secret";
    // A token such as fdoa-a480ce8951daa73262734cf102641994c1e55e7cdf4c02b6
    const char *token = "my_merchant_token";

    // The nonce is a random number (bytes), something like "6057786719490086000"
    const char *nonce = prng.genRandom(8,"decimal");
    std::cout << "nonce = " << nonce << "\r\n";

    CkDateTime dtNow;
    dtNow.SetFromCurrentSystemTime();
    CkStringBuilder sbTimestamp;
    // Get the epoch timestamp in seconds
    sbTimestamp.Append(dtNow.getAsUnixTimeStr(false));
    // Change it to milliseconds
    sbTimestamp.Append("000");
    // The timestamp is a number similar to this: 1546011905000 (which is a timestamp taken on 28-Dec-2018).
    const char *timestamp = sbTimestamp.getAsString();
    std::cout << "timestamp = " << timestamp << "\r\n";

    // Generate the following JSON request body:
    // 	{
    // 	  "merchant_ref": "Astonishing-Sale",
    // 	  "transaction_type": "authorize",
    // 	  "method": "token",
    // 	  "amount": "200",
    // 	  "currency_code": "USD",
    // 	  "token": {
    // 	    "token_type": "FDToken",
    // 	    "token_data": {
    // 	      "type": "visa",
    // 	      "value": "2537446225198291",
    // 	      "cardholder_name": "JohnSmith",
    // 	      "exp_date": "1030",
    // 	      "special_payment": "B"
    // 	    }
    // 	  }
    // 	}

    CkJsonObject json;
    json.UpdateString("merchant_ref","Astonishing-Sale");
    json.UpdateString("transaction_type","authorize");
    json.UpdateString("method","token");
    json.UpdateString("amount","200");
    json.UpdateString("currency_code","USD");
    json.UpdateString("token.token_type","FDToken");
    json.UpdateString("token.token_data.type","visa");
    json.UpdateString("token.token_data.value","2537446225198291");
    json.UpdateString("token.token_data.cardholder_name","JohnSmith");
    json.UpdateString("token.token_data.exp_date","1030");
    json.UpdateString("token.token_data.special_payment","B");

    // string hashData = apiKey + nonce + timestamp + token + jsonString;
    CkStringBuilder sbHmacData;
    sbHmacData.Append(apiKey);
    sbHmacData.Append(nonce);
    sbHmacData.Append(timestamp);
    sbHmacData.Append(token);
    sbHmacData.Append(json.emit());

    // HMAC the data to produce a hex string.
    crypt.put_EncodingMode("hexlower");
    crypt.put_MacAlgorithm("hmac");
    crypt.SetMacKeyString(apiSecret);
    crypt.put_HashAlgorithm("sha256");
    crypt.put_Charset("utf-8");
    const char *hexHash = crypt.macStringENC(sbHmacData.getAsString());

    // Now base64 encode the hex string:
    CkStringBuilder sbBase64Hash;
    sbBase64Hash.Append(hexHash);
    sbBase64Hash.Encode("base64","utf-8");

    std::cout << "This is the Authorization header to be sent with the payeezy request:" << "\r\n";
    std::cout << "Authorization: " << sbBase64Hash.getAsString() << "\r\n";
    }