Some cryptographic questions

Hello! I'm new to DataX and when I was browsing the code I found some potential cryptographic risks.

1. DES and 3DES used
DES is used [here](https://github.com/alibaba/DataX/blob/master/common/src/main/java/com/alibaba/datax/common/util/DESCipher.java#L39) and 3DES is used [here](https://github.com/alibaba/DataX/blob/master/core/src/main/java/com/alibaba/datax/core/util/SecretUtil.java#L46). Both DES and 3DES are considered insecure. Is it for compacity?
```java
private final static String DES = "DES";
```
```java
public static final String KEY_ALGORITHM_3DES = "DESede";
```

2. Hardcoded key with an empty string
The key is hardcoded [here](https://github.com/alibaba/DataX/blob/master/common/src/main/java/com/alibaba/datax/common/util/DESCipher.java#L38). I know this empty string is a default key and will only be available when the key is not provided. But a default key with an empty string is also considered insecure, and generating a random string for the default key may be a better choice.
```java
public static final String KEY = "";
```

Start by reading common/src/main/java/com/alibaba/datax/common/util/DESCipher.java and core/src/main/java/com/alibaba/datax/core/util/SecretUtil.java, focusing on the DES, 3DES, and default-key usages identified in the issue. Determine the intended security requirements and replacement approach; done should address the reported insecure algorithms and empty default key or document why they must remain.

Written by the indexing model from the issue text.