Pascal (Lazarus/Delphi)

PRODA Get OAuth2 Access Token using JWT

See more PRODA Examples

Demonstrates how to get an OAuth2 access token for the PRODA Australian Government Online Services using a JWT. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Jwt,
  Chilkat.HttpResponse,
  Chilkat.HttpRequest,
  Chilkat.JsonObject,
  Chilkat.PrivateKey,
  Chilkat.Http;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  privKey: TPrivateKey;
  jwt: TJwt;
  jose: TJsonObject;
  claims: TJsonObject;
  curDateTime: Integer;
  jwtToken: string;
  http: THttp;
  req: THttpRequest;
  resp: THttpResponse;

begin
  success := False;

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

  //  First create a JWT to be sent in the POST to https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token

  privKey := TPrivateKey.Create;

  //  Load an RSA private key from a PEM file.
  //  Chilkat provides alternative methods to load from other formats, or to load from a string or binary data.
  success := privKey.LoadEncryptedPemFile('qa_data/pem/rsa_passwd.pem','passwd');
  if (success = False) then
    begin
      WriteLn(privKey.LastErrorText);
      Exit;
    end;

  jwt := TJwt.Create;

  //  Build the JOSE header
  jose := TJsonObject.Create;
  //  Use RS256.  Pass the string "RS384" or "RS512" to use RSA with SHA-384 or SHA-512.
  success := jose.AppendString('alg','RS256');
  success := jose.AppendString('typ','JWT');
  success := jose.AppendString('kid','test-device');

  //  Now build the JWT claims (also known as the payload)
  claims := TJsonObject.Create;
  success := claims.AppendString('iss','9646844092');
  success := claims.AppendString('sub','test-device');
  success := claims.AppendString('aud','https://proda.humanservices.gov.au');

  //  Set the timestamp of when the JWT was created to now.
  curDateTime := jwt.GenNumericDate(0);
  success := claims.AddIntAt(-1,'iat',curDateTime);

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

  //  Produce the smallest possible JWT:
  jwt.AutoCompact := True;

  //  Create the JWT token.  This is where the RSA signature is created.
  jwtToken := jwt.CreateJwtPk(jose.Emit(),claims.Emit(),privKey);

  //  ---------------------------------------------------------------------
  //  Build and send the POST, which should look something like this:

  //  POST https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token HTTP/1.1
  //  Content-Type: application/x-www-form-urlencoded
  //  Content-Length: 666
  //  Host: vnd.proda.humanservices.gov.au
  //  
  //  grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer&assertion=<jwt>&client_id=VendorClient03

  http := THttp.Create;

  req := THttpRequest.Create;
  req.HttpVerb := 'POST';
  req.ContentType := 'application/x-www-form-urlencoded';

  //  Add the request params.
  req.AddParam('grant_type','urn:ietf:params:oauth:grant-type:jwt-bearer');
  req.AddParam('assertion',jwtToken);
  req.AddParam('client_id','VendorClient03');

  resp := THttpResponse.Create;
  success := http.HttpReq('https://vnd.proda.humanservices.gov.au/mga/sps/oauth/oauth20/token',req,resp);
  if (success = False) then
    begin
      WriteLn(http.LastErrorText);
      Exit;
    end;

  WriteLn('Response status code = ' + resp.StatusCode);
  WriteLn('Response body:');
  WriteLn(resp.BodyStr);


  privKey.Free;
  jwt.Free;
  jose.Free;
  claims.Free;
  http.Free;
  req.Free;
  resp.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.