(Unicode C++) Walmart Partner API Authentication (Generate a Signature for a Request)

Demonstrates how to generate a signature for a Walmart Partner REST API call.

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#include <CkDateTimeW.h>
#include <CkStringBuilderW.h>
#include <CkPrivateKeyW.h>
#include <CkRsaW.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 *consumerId = L"b68d2a72....";
    const wchar_t *baseUrl = L"https://marketplace.walmartapis.com/v2/feeds";
    // This is your Base64 encoded private key
    const wchar_t *privateEncodedStr = L"MIICeAIBADANBgkqhkiG9w0BAQEFAA......";
    const wchar_t *httpMethod = L"GET";

    // We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
    CkDateTimeW dt;
    // Set bLocal = true for a timestamp in the local timezone.  Set bLocal = false for a UTC timestamp.
    bool bLocal = false;
    // This gets the timestamp in seconds, not milliseconds.
    int timeStampVal = dt.GetAsUnixTime(bLocal);

    // Build the string to sign.
    CkStringBuilderW sbStringToSign;
    sbStringToSign.Append(consumerId);
    sbStringToSign.Append(L"\n");
    sbStringToSign.Append(baseUrl);
    sbStringToSign.Append(L"\n");
    sbStringToSign.Append(httpMethod);
    sbStringToSign.Append(L"\n");
    sbStringToSign.AppendInt(timeStampVal);
    // We add three zero's so that the timestamp value is in milliseconds.
    // We don't care about accuracy down to less than a second.
    // All the server cares about is that the request was signed at the current date/time
    // within some reasonable margin of error (to account for systems having clocks
    // that may be slightly different).
    sbStringToSign.Append(L"000\n");

    CkPrivateKeyW privKey;
    // Load the private key into a private key object.
    // Note: Technically the private key is not PEM because it lacks the header/footer strings
    // used for PEM.  However, the LoadPem method will still accept it and load it correctly.
    success = privKey.LoadPem(privateEncodedStr);
    if (success != true) {
        wprintf(L"%s\n",privKey.lastErrorText());
        return;
    }

    CkRsaW rsa;
    success = rsa.ImportPrivateKeyObj(privKey);
    if (success != true) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    // We want a base64 signature string.
    rsa.put_EncodingMode(L"base64");

    const wchar_t *signatureString = rsa.signStringENC(sbStringToSign.getAsString(),L"SHA256");
    if (rsa.get_LastMethodSuccess() != true) {
        wprintf(L"%s\n",rsa.lastErrorText());
        return;
    }

    wprintf(L"Signature String: %s\n",signatureString);
    }