decrypt static method

EasyPacket? decrypt(dynamic data, String? pwd)

将收到的数据进行解密，采用随机生成iv和key的AES解密算法（CBC、Pkcs7）

• data 要解密的数据
• pwd 解密的密码

Implementation

static EasyPacket? decrypt(dynamic data, String? pwd) {
  try {
    if (pwd != null) {
      final hmacSha256 = Hmac(sha256, utf8.encode(pwd)); // HMAC-SHA256
      Uint8List bytes;
      if (data is String) {
        bytes = base64Decode(data);
      } else if (data is ByteBuffer) {
        bytes = data.asUint8List(); //Web is NativeByteBuffer
      } else if (data is Uint8List) {
        bytes = data; //Native is Uint8List
      } else {
        return null;
      }
      final salt = bytes.sublist(0, 16);
      final iv = bytes.sublist(16, 32);
      final key = Uint8List.fromList(hmacSha256.convert(salt).bytes);
      final body = bytes.sublist(32);
      final aesCrypto = Encrypter(AES(Key(key), mode: AESMode.cbc, padding: 'PKCS7'));
      final decRes = aesCrypto.decrypt(Encrypted(body), iv: IV(iv));
      return EasyPacket.fromJson(jsonDecode(decRes));
    } else {
      return EasyPacket.fromJson(jsonDecode(data is String ? data : String.fromCharCodes(data)));
    }
  } catch (error) {
    return null;
  }
}