Pascal (Lazarus/Delphi)

Payeezy HMAC Computation

See more HTTP Misc Examples

Demonstrates how to calculate the HMAC for a Payeezy REST request. 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.JsonObject,
  Chilkat.StringBuilder,
  Chilkat.Prng,
  Chilkat.CkDateTime,
  Chilkat.Crypt2;

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

procedure RunDemo;
var
  success: Boolean;
  crypt: TCrypt2;
  prng: TPrng;
  apiKey: string;
  apiSecret: string;
  token: string;
  nonce: string;
  dtNow: TCkDateTime;
  sbTimestamp: TStringBuilder;
  timestamp: string;
  json: TJsonObject;
  sbHmacData: TStringBuilder;
  hexHash: string;
  sbBase64Hash: TStringBuilder;

begin
  success := False;

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

  crypt := TCrypt2.Create;
  prng := TPrng.Create;

  //  An API key such as y6pWAJNyJyjGv66IsVuWnklkKUPFbb0a
  apiKey := 'my_api_key';
  //  An API secret such as 86fbae7030253af3cd15faef2a1f4b67353e41fb6799f576b5093ae52901e6f7
  apiSecret := 'my_api_secret';
  //  A token such as fdoa-a480ce8951daa73262734cf102641994c1e55e7cdf4c02b6
  token := 'my_merchant_token';

  //  The nonce is a random number (bytes), something like "6057786719490086000"
  nonce := prng.GenRandom(8,'decimal');
  WriteLn('nonce = ' + nonce);

  dtNow := TCkDateTime.Create;
  dtNow.SetFromCurrentSystemTime();
  sbTimestamp := TStringBuilder.Create;
  //  Get the epoch timestamp in seconds
  sbTimestamp.Append(dtNow.GetAsUnixTimeStr(False));
  //  Change it to milliseconds
  sbTimestamp.Append('000');
  //  The timestamp is a number similar to this: 1546011905000 (which is a timestamp taken on 28-Dec-2018).
  timestamp := sbTimestamp.GetAsString();
  WriteLn('timestamp = ' + timestamp);

  //  Generate the following JSON request body:
  //  	{
  //  	  "merchant_ref": "Astonishing-Sale",
  //  	  "transaction_type": "authorize",
  //  	  "method": "token",
  //  	  "amount": "200",
  //  	  "currency_code": "USD",
  //  	  "token": {
  //  	    "token_type": "FDToken",
  //  	    "token_data": {
  //  	      "type": "visa",
  //  	      "value": "2537446225198291",
  //  	      "cardholder_name": "JohnSmith",
  //  	      "exp_date": "1030",
  //  	      "special_payment": "B"
  //  	    }
  //  	  }
  //  	}

  json := TJsonObject.Create;
  json.UpdateString('merchant_ref','Astonishing-Sale');
  json.UpdateString('transaction_type','authorize');
  json.UpdateString('method','token');
  json.UpdateString('amount','200');
  json.UpdateString('currency_code','USD');
  json.UpdateString('token.token_type','FDToken');
  json.UpdateString('token.token_data.type','visa');
  json.UpdateString('token.token_data.value','2537446225198291');
  json.UpdateString('token.token_data.cardholder_name','JohnSmith');
  json.UpdateString('token.token_data.exp_date','1030');
  json.UpdateString('token.token_data.special_payment','B');

  //  string hashData = apiKey + nonce + timestamp + token + jsonString;
  sbHmacData := TStringBuilder.Create;
  sbHmacData.Append(apiKey);
  sbHmacData.Append(nonce);
  sbHmacData.Append(timestamp);
  sbHmacData.Append(token);
  sbHmacData.Append(json.Emit());

  //  HMAC the data to produce a hex string.
  crypt.EncodingMode := 'hexlower';
  crypt.MacAlgorithm := 'hmac';
  crypt.SetMacKeyString(apiSecret);
  crypt.HashAlgorithm := 'sha256';
  crypt.Charset := 'utf-8';
  hexHash := crypt.MacStringENC(sbHmacData.GetAsString());

  //  Now base64 encode the hex string:
  sbBase64Hash := TStringBuilder.Create;
  sbBase64Hash.Append(hexHash);
  sbBase64Hash.Encode('base64','utf-8');

  WriteLn('This is the Authorization header to be sent with the payeezy request:');
  WriteLn('Authorization: ' + sbBase64Hash.GetAsString());


  crypt.Free;
  prng.Free;
  dtNow.Free;
  sbTimestamp.Free;
  json.Free;
  sbHmacData.Free;
  sbBase64Hash.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.