(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 <CkDateTime.h>
#include <CkStringBuilder.h>
#include <CkPrivateKey.h>
#include <CkRsa.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 char *consumerId = "b68d2a72....";
    const char *baseUrl = "https://marketplace.walmartapis.com/v2/feeds";
    // This is your Base64 encoded private key
    const char *privateEncodedStr = "MIICeAIBADANBgkqhkiG9w0BAQEFAA......";
    const char *httpMethod = "GET";

    // We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
    CkDateTime 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.
    CkStringBuilder sbStringToSign;
    sbStringToSign.Append(consumerId);
    sbStringToSign.Append("\n");
    sbStringToSign.Append(baseUrl);
    sbStringToSign.Append("\n");
    sbStringToSign.Append(httpMethod);
    sbStringToSign.Append("\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("000\n");

    CkPrivateKey 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) {
        std::cout << privKey.lastErrorText() << "\r\n";
        return;
    }

    CkRsa rsa;
    success = rsa.ImportPrivateKeyObj(privKey);
    if (success != true) {
        std::cout << rsa.lastErrorText() << "\r\n";
        return;
    }

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

    const char *signatureString = rsa.signStringENC(sbStringToSign.getAsString(),"SHA256");
    if (rsa.get_LastMethodSuccess() != true) {
        std::cout << rsa.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Signature String: " << signatureString << "\r\n";
    }