Dart

Payeezy HMAC Computation

See more HTTP Misc Examples

Demonstrates how to calculate the HMAC for a Payeezy REST request. Dart

import 'package:chilkat/chilkat.dart';

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

  final crypt = CkCrypt2();
  final prng = CkPrng();

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

  // The nonce is a random number (bytes), something like "6057786719490086000"
  final nonce = prng.genRandom(8, 'decimal');
  print('nonce = $nonce');

  final dtNow = CkDateTime();
  dtNow.setFromCurrentSystemTime();
  final sbTimestamp = CkStringBuilder();
  // 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).
  final timestamp = sbTimestamp.getAsString();
  print('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"
  // 	    }
  // 	  }
  // 	}

  final json = CkJsonObject();
  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;
  final sbHmacData = CkStringBuilder();
  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';
  final hexHash = crypt.macStringENC(sbHmacData.getAsString());

  // Now base64 encode the hex string:
  final sbBase64Hash = CkStringBuilder();
  sbBase64Hash.append(hexHash);
  sbBase64Hash.encode('base64', 'utf-8');

  print('This is the Authorization header to be sent with the payeezy request:');
  print('Authorization: ${sbBase64Hash.getAsString()}');
}