flutter_wsse.dart

Future<Response> get(String url) async {
    String wsseHeader = await generateAuthHeader();
    final response = await httpClient.get(url,
        headers: {
          HttpHeaders.contentTypeHeader: 'application/vnd.api+json',
          'Authorization': 'WSSE profile="UsernameToken"',
          'X-WSSE': wsseHeader
        },

    );
    return response;
  }

Future<String> generateAuthHeader() async {
    String userName = 'username';
    String apiKey = 'apikey';
    var uuid = Uuid();
    String md5Str = md5.convert(utf8.encode(uuid.v1())).toString();
    String none = base64.encode(utf8.encode(md5Str));
    String created = DateTime.now().toUtc().toIso8601String();
    String input = utf8.decode(base64.decode(none)) +
        created + apiKey;
    String digest = base64.encode(sha1.convert(utf8.encode(input)).bytes);

    String wsseHeader = 'UsernameToken Username="$userName", PasswordDigest="$digest", Nonce="$none", Created="$created"';
    return wsseHeader;
  }