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

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, StringBuilder, PrivateKey, Rsa, CkDateTime;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
consumerId: PWideChar;
baseUrl: PWideChar;
privateEncodedStr: PWideChar;
httpMethod: PWideChar;
dt: HCkDateTime;
bLocal: Boolean;
timeStampVal: Integer;
sbStringToSign: HCkStringBuilder;
privKey: HCkPrivateKey;
rsa: HCkRsa;
signatureString: PWideChar;

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 := CkDateTime_Create();
// Set bLocal = True for a timestamp in the local timezone.  Set bLocal = False for a UTC timestamp.
bLocal := False;
// This gets the timestamp in seconds, not milliseconds.
timeStampVal := CkDateTime_GetAsUnixTime(dt,bLocal);

// Build the string to sign.
sbStringToSign := CkStringBuilder_Create();
CkStringBuilder_Append(sbStringToSign,consumerId);
CkStringBuilder_Append(sbStringToSign,#10);
CkStringBuilder_Append(sbStringToSign,baseUrl);
CkStringBuilder_Append(sbStringToSign,#10);
CkStringBuilder_Append(sbStringToSign,httpMethod);
CkStringBuilder_Append(sbStringToSign,#10);
CkStringBuilder_AppendInt(sbStringToSign,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).
CkStringBuilder_Append(sbStringToSign,'000' + #10);

privKey := CkPrivateKey_Create();
// 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 := CkPrivateKey_LoadPem(privKey,privateEncodedStr);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privKey));
    Exit;
  end;

rsa := CkRsa_Create();
success := CkRsa_ImportPrivateKeyObj(rsa,privKey);
if (success <> True) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

// We want a base64 signature string.
CkRsa_putEncodingMode(rsa,'base64');

signatureString := CkRsa__signStringENC(rsa,CkStringBuilder__getAsString(sbStringToSign),'SHA256');
if (CkRsa_getLastMethodSuccess(rsa) <> True) then
  begin
    Memo1.Lines.Add(CkRsa__lastErrorText(rsa));
    Exit;
  end;

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

CkDateTime_Dispose(dt);
CkStringBuilder_Dispose(sbStringToSign);
CkPrivateKey_Dispose(privKey);
CkRsa_Dispose(rsa);

end;