(.NET Core 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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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

bool success;

string consumerId = "b68d2a72....";
string baseUrl = "https://marketplace.walmartapis.com/v2/feeds";
// This is your Base64 encoded private key
string privateEncodedStr = "MIICeAIBADANBgkqhkiG9w0BAQEFAA......";
string httpMethod = "GET";

// We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
Chilkat.CkDateTime dt = new Chilkat.CkDateTime();
// 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.
Chilkat.StringBuilder sbStringToSign = new Chilkat.StringBuilder();
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");

Chilkat.PrivateKey privKey = new Chilkat.PrivateKey();
// 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) {
    Debug.WriteLine(privKey.LastErrorText);
    return;
}

Chilkat.Rsa rsa = new Chilkat.Rsa();
success = rsa.ImportPrivateKeyObj(privKey);
if (success != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// We want a base64 signature string.
rsa.EncodingMode = "base64";

string signatureString = rsa.SignStringENC(sbStringToSign.GetAsString(),"SHA256");
if (rsa.LastMethodSuccess != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

Debug.WriteLine("Signature String: " + signatureString);