(Delphi ActiveX) Walmart Partner API Authentication (Generate a Signature for a Request)

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

Chilkat for Delphi Downloads Chilkat ActiveX DLL for Delphi Chilkat non-ActiveX DLL for Delphi * The examples here use the ActiveX DLL.

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
consumerId: WideString;
baseUrl: WideString;
privateEncodedStr: WideString;
httpMethod: WideString;
dt: TCkDateTime;
bLocal: Integer;
timeStampVal: Integer;
sbStringToSign: TChilkatStringBuilder;
privKey: TPrivateKey;
rsa: TChilkatRsa;
signatureString: WideString;

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

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

// We need a timestamp in decimal string form representing the number of milliseconds since Jan 01 1970 UTC.
dt := TCkDateTime.Create(Self);
// Set bLocal = 1 for a timestamp in the local timezone.  Set bLocal = 0 for a UTC timestamp.
bLocal := 0;
// This gets the timestamp in seconds, not milliseconds.
timeStampVal := dt.GetAsUnixTime(bLocal);

// Build the string to sign.
sbStringToSign := TChilkatStringBuilder.Create(Self);
sbStringToSign.Append(consumerId);
sbStringToSign.Append(#10);
sbStringToSign.Append(baseUrl);
sbStringToSign.Append(#10);
sbStringToSign.Append(httpMethod);
sbStringToSign.Append(#10);
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' + #10);

privKey := TPrivateKey.Create(Self);
// 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 <> 1) then
  begin
    Memo1.Lines.Add(privKey.LastErrorText);
    Exit;
  end;

rsa := TChilkatRsa.Create(Self);
success := rsa.ImportPrivateKeyObj(privKey.ControlInterface);
if (success <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

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

signatureString := rsa.SignStringENC(sbStringToSign.GetAsString(),'SHA256');
if (rsa.LastMethodSuccess <> 1) then
  begin
    Memo1.Lines.Add(rsa.LastErrorText);
    Exit;
  end;

Memo1.Lines.Add('Signature String: ' + signatureString);
end;