(Delphi DLL) Get Access Token using a Pre-Created JSON Web Token

Demonstrates how to get an access token using a pre-created JSON Web Token (JWT).

For more information, see https://developer.abnamro.com/get-started#headingFive

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, Jwt, HttpResponse, HttpRequest, JsonObject, PrivateKey, Http;

...

procedure TForm1.Button1Click(Sender: TObject);
var
privkey: HCkPrivateKey;
success: Boolean;
jwt: HCkJwt;
jsonHeader: HCkJsonObject;
jsonPayload: HCkJsonObject;
curDateTime: Integer;
jwtStr: PWideChar;
http: HCkHttp;
req: HCkHttpRequest;
resp: HCkHttpResponse;
json: HCkJsonObject;

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

// We're going to duplicate this CURL statement:
// curl -X POST https://api-sandbox.abnamro.com/v1/oauth/token \
// -H "Content-Type: application/x-www-form-urlencoded" \
// -H "API-Key: xxxxxx" \
// -d 'client_assertion_type=urn:ietf:params:oauth:client-assertion-type:jwt-bearer&grant_type=client_credentials&client_assertion=eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJ4eHh4eHgiLCJleHAiOiIxNDk5OTQ3NjY4IiwiaXNzIjoibWUiLCJhdWQiOiJodHRwczovL2F1dGgtc2FuZGJveC5hYm5hbXJvLmNvbS9vYXV0aC90b2tlbiJ9.jGwHKG_YjgKpR8NPpaLu6nJ97obeP2vcxg6fOWBKdJ0&scope=tikkie'

// Load our pre-creaed private key PEM file.
// Note: Please share your public key along with your app name and developer email id at api.support@nl.abnamro.com. 
// Token generation will not work unless public key is associated with your app.
privkey := CkPrivateKey_Create();

success := CkPrivateKey_LoadPemFile(privkey,'qa_data/pem/abnAmroPrivateKey.pem');
if (success = False) then
  begin
    Memo1.Lines.Add(CkPrivateKey__lastErrorText(privkey));
    Exit;
  end;

// Create the JWT.
jwt := CkJwt_Create();

// Create the header:
// {
//     "typ": "JWT",
//     "alg": "RS256"
// }
jsonHeader := CkJsonObject_Create();
CkJsonObject_UpdateString(jsonHeader,'typ','JWT');
CkJsonObject_UpdateString(jsonHeader,'alg','RS256');

// Create the payload:
// {
//     "nbf": 1499947668,
//     "exp": 1499948668,
//     "iss": "me",
//     "sub": "anApiKey",
//     "aud": "https://auth-sandbox.abnamro.com/oauth/token"
// }
jsonPayload := CkJsonObject_Create();

curDateTime := CkJwt_GenNumericDate(jwt,0);

// Set the "not process before" timestamp to now.
success := CkJsonObject_AddIntAt(jsonPayload,-1,'nbf',curDateTime);

// Set the timestamp defining an expiration time (end time) for the token
// to be now + 1 hour (3600 seconds)
success := CkJsonObject_AddIntAt(jsonPayload,-1,'exp',curDateTime + 3600);

CkJsonObject_UpdateString(jsonPayload,'iss','me');
CkJsonObject_UpdateString(jsonPayload,'sub','anApiKey');
CkJsonObject_UpdateString(jsonPayload,'aud','https://auth-sandbox.abnamro.com/oauth/token');

// Produce the smallest possible JWT:
CkJwt_putAutoCompact(jwt,True);

jwtStr := CkJwt__createJwtPk(jwt,CkJsonObject__emit(jsonHeader),CkJsonObject__emit(jsonPayload),privkey);
if (CkJwt_getLastMethodSuccess(jwt) <> True) then
  begin
    Memo1.Lines.Add(CkJwt__lastErrorText(jwt));
    Exit;
  end;

http := CkHttp_Create();

req := CkHttpRequest_Create();
CkHttpRequest_AddParam(req,'client_assertion_type','urn:ietf:params:oauth:client-assertion-type:jwt-bearer');
CkHttpRequest_AddParam(req,'grant_type','client_credentials');
CkHttpRequest_AddParam(req,'client_assertion',jwtStr);
CkHttpRequest_AddParam(req,'scope','tikkie');

resp := CkHttp_PostUrlEncoded(http,'https://api-sandbox.abnamro.com/v1/oauth/token',req);
if (CkHttp_getLastMethodSuccess(http) = False) then
  begin
    Memo1.Lines.Add(CkHttp__lastErrorText(http));
    Exit;
  end;

if (CkHttpResponse_getStatusCode(resp) <> 200) then
  begin
    Memo1.Lines.Add(CkHttpResponse__bodyStr(resp));
    CkHttpResponse_Dispose(resp);
    Exit;
  end;

// Get the JSON result:
// {
//     "access_token": "{your access token}",
//     "expires_in": "{duration of validity in seconds}",
//     "scope": "{scope(s) for which the access token is valid}",
//     "token_type": "{it is always Bearer}"
// }
json := CkJsonObject_Create();
CkJsonObject_Load(json,CkHttpResponse__bodyStr(resp));
Memo1.Lines.Add('access_token: ' + CkJsonObject__stringOf(json,'access_token'));
Memo1.Lines.Add('token_type: ' + CkJsonObject__stringOf(json,'token_type'));
Memo1.Lines.Add('expires_in: ' + CkJsonObject__stringOf(json,'expires_in'));
Memo1.Lines.Add('scope: ' + CkJsonObject__stringOf(json,'scope'));

CkHttpResponse_Dispose(resp);

CkPrivateKey_Dispose(privkey);
CkJwt_Dispose(jwt);
CkJsonObject_Dispose(jsonHeader);
CkJsonObject_Dispose(jsonPayload);
CkHttp_Dispose(http);
CkHttpRequest_Dispose(req);
CkJsonObject_Dispose(json);

end;