Dart Requires Chilkat v11.0.0+

ING Open Banking OAuth2 Client Credentials

See more OAuth2 Examples

Demonstrates how to get an access token for the ING Open Banking APIs using client credentials. 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 cert = CkCert();
  try {
    cert.loadFromFile('qa_data/certs_and_keys/ING/example_client_tls.cer');
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  final bdPrivKey = CkBinData();
  try {
    bdPrivKey.loadFile('qa_data/certs_and_keys/ING/example_client_tls.key');
  } on ChilkatException {
    print('Failed to load example_client_tls.key');
    return;
  }

  // The OAuth 2.0 client_id for these certificates is e77d776b-90af-4684-bebc-521e5b2614dd. 
  // Please note down this client_id since you will need it in the next steps to call the API.

  final privKey = CkPrivateKey();
  try {
    privKey.loadAnyFormat(bdPrivKey, '');
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  // Associate the private key with the certificate.
  try {
    cert.setPrivateKey(privKey);
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  final http = CkHttp();

  try {
    http.setSslClientCert(cert);
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  // Calculate the Digest and add the "Digest" header.  Do the equivalent of this:
  // payload="grant_type=client_credentials"
  // payloadDigest=`echo -n "$payload" | openssl dgst -binary -sha256 | openssl base64`
  // digest=SHA-256=$payloadDigest
  final crypt = CkCrypt2();
  crypt.hashAlgorithm = 'SHA256';
  crypt.encodingMode = 'base64';
  final payload = 'grant_type=client_credentials';
  final payloadDigest = crypt.hashStringENC(payload);

  // Calculate the current date/time and add the Date header.  
  // reqDate=$(LC_TIME=en_US.UTF-8 date -u "+%a, %d %b %Y %H:%M:%S GMT")  
  final dt = CkDateTime();
  dt.setFromCurrentSystemTime();
  // The desire date/time format is the "RFC822" format.
  http.setRequestHeader('Date', dt.getAsRfc822(false));

  // Calculate signature for signing your request
  // Duplicate the following code:

  // 	httpMethod="post"
  // 	reqPath="/oauth2/token"
  // 	signingString="(request-target): $httpMethod $reqPath
  // 	date: $reqDate
  // 	digest: $digest"
  // 	signature=`printf "$signingString" | openssl dgst -sha256 -sign "${certPath}example_client_signing.key" -passin "pass:changeit" | openssl base64 -A`

  final httpMethod = 'POST';
  final reqPath = '/oauth2/token';

  final sbStringToSign = CkStringBuilder();
  sbStringToSign.append('(request-target): ');
  sbStringToSign.append(httpMethod);
  sbStringToSign.toLowercase();
  sbStringToSign.append(' ');
  sbStringToSign.appendLine(reqPath, false);

  sbStringToSign.append('date: ');
  sbStringToSign.appendLine(dt.getAsRfc822(false), false);

  sbStringToSign.append('digest: SHA-256=');
  sbStringToSign.append(payloadDigest);

  final signingPrivKey = CkPrivateKey();
  try {
    signingPrivKey.loadPemFile('qa_data/certs_and_keys/ING/example_client_signing.key');
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  final rsa = CkRsa();
  try {
    rsa.usePrivateKey(signingPrivKey);
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  rsa.encodingMode = 'base64';
  final b64Signature = rsa.signStringENC(sbStringToSign.getAsString(), 'SHA256');

  final sbAuthHdrVal = CkStringBuilder();
  sbAuthHdrVal.append('Signature keyId="e77d776b-90af-4684-bebc-521e5b2614dd",');
  sbAuthHdrVal.append('algorithm="rsa-sha256",');
  sbAuthHdrVal.append('headers="(request-target) date digest",');
  sbAuthHdrVal.append('signature="');
  sbAuthHdrVal.append(b64Signature);
  sbAuthHdrVal.append('"');

  final sbDigestHdrVal = CkStringBuilder();
  sbDigestHdrVal.append('SHA-256=');
  sbDigestHdrVal.append(payloadDigest);

  // Do the following CURL statement:

  // 	curl -i -X POST "${httpHost}${reqPath}" \
  // 	-H 'Accept: application/json' \
  // 	-H 'Content-Type: application/x-www-form-urlencoded' \
  // 	-H "Digest: ${digest}" \
  // 	-H "Date: ${reqDate}" \
  // 	-H "authorization: Signature keyId=\"$keyId\",algorithm=\"rsa-sha256\",headers=\"(request-target) date digest\",signature=\"$signature\"" \
  // 	-d "${payload}" \
  // 	--cert "${certPath}tlsCert.crt" \
  // 	--key "${certPath}tlsCert.key"

  final req = CkHttpRequest();
  req.addParam('grant_type', 'client_credentials');
  req.addHeader('Accept', 'application/json');
  req.addHeader('Date', dt.getAsRfc822(false));
  req.addHeader('Digest', sbDigestHdrVal.getAsString());
  req.addHeader('Authorization', sbAuthHdrVal.getAsString());

  req.httpVerb = 'POST';
  req.contentType = 'application/x-www-form-urlencoded';

  final resp = CkHttpResponse();
  try {
    http.httpReq('https://api.sandbox.ing.com/oauth2/token', req, resp);
  } on ChilkatException catch (ex) {
    print(ex.lastErrorText);
    return;
  }

  // If successful, the status code = 200
  print('Response Status Code: ${resp.statusCode}');
  print(resp.bodyStr);

  final json = CkJsonObject();
  json.load(resp.bodyStr);

  json.emitCompact = false;
  print(json.emit());

  // A successful response contains an access token such as:
  // {
  //   "access_token": "eyJhbGc ... bxI_SoPOBH9xmoM",
  //   "expires_in": 905,
  //   "scope": "payment-requests:view payment-requests:create payment-requests:close greetings:view virtual-ledger-accounts:fund-reservation:create virtual-ledger-accounts:fund-reservation:delete virtual-ledger-accounts:balance:view",
  //   "token_type": "Bearer",
  //   "keys": [
  //     {
  //       "kty": "RSA",
  //       "n": "3l3rdz4...04VPkdV",
  //       "e": "AQAB",
  //       "use": "sig",
  //       "alg": "RS256",
  //       "x5t": "3c396700fc8cd709cf9cb5452a22bcde76985851"
  //     }
  //   ],
  //   "client_id": "e77d776b-90af-4684-bebc-521e5b2614dd"
  // }

  // Use this online tool to generate parsing code from sample JSON: 
  // Generate Parsing Code from JSON

  var kty = '';
  var n = '';
  var e = '';
  var use = '';
  var alg = '';
  var x5t = '';

  final accessToken = json.stringOf('access_token');
  final expiresIn = json.intOf('expires_in');
  final scope = json.stringOf('scope');
  final tokenType = json.stringOf('token_type');
  final clientId = json.stringOf('client_id');
  var i = 0;
  final countI = json.sizeOfArray('keys');
  while (i < countI) {
    json.i = i;
    kty = json.stringOf('keys[i].kty');
    n = json.stringOf('keys[i].n');
    e = json.stringOf('keys[i].e');
    use = json.stringOf('keys[i].use');
    alg = json.stringOf('keys[i].alg');
    x5t = json.stringOf('keys[i].x5t');
    i++;
  }

  // This example will save the JSON containing the access key to a file so that
  // a subsequent example can load it and then use the access key for a request, such as to create a payment request.
  json.writeFile('qa_data/tokens/ing_access_token.json');
}