AES解密，key长度不够16处理

AES解密，有时会遇到key长度不够16位的场景，如何处理，如下以AES-128-ECB解密模式为例进行展示。

public class Test {

    public static void main(String[] args) throws Exception {
        String str="htNbZOHaXvMimfeSoK5jQg==";//AES-128-ECB加密后的密文
        String decStr=decrypt(str,"123");
        System.out.println(decStr);

    }
    /* *
     * @Author na_tion
     * @Description AES解密函数
     * 也可以使用其他网上常见的函数
     * @Date 10:53 上午 2020/04/10
     * @Param [content, passwd]
     * @return java.lang.String
     **/
    public static String decrypt(String content, String passwd) {
        try {
            Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");// 创建密码器
            SecretKeySpec key = new SecretKeySpec(passwd.getBytes(), "AES");
            cipher.init(Cipher.DECRYPT_MODE, key);// 初始化
            byte[] result = new BASE64Decoder().decodeBuffer(content);
            return new String(cipher.doFinal(result)); // 解密
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

}

如上代码，会报如下错误（提示key长度为3字节，不够16字节）

java.security.InvalidKeyException: Invalid AES key length: 3 bytes
	at com.sun.crypto.provider.AESCrypt.init(AESCrypt.java:87)
	at com.sun.crypto.provider.ElectronicCodeBook.init(ElectronicCodeBook.java:94)
	at com.sun.crypto.provider.CipherCore.init(CipherCore.java:591)
	at com.sun.crypto.provider.CipherCore.init(CipherCore.java:467)
	at com.sun.crypto.provider.AESCipher.engineInit(AESCipher.java:313)
	at javax.crypto.Cipher.implInit(Cipher.java:801)
	at javax.crypto.Cipher.chooseProvider(Cipher.java:863)
	at javax.crypto.Cipher.init(Cipher.java:1248)
	at javax.crypto.Cipher.init(Cipher.java:1185)

处理方法：

用\0补齐不够的位数，代码示例如下

    public static void main(String[] args) throws Exception {
        String str="htNbZOHaXvMimfeSoK5jQg==";//AES-128-ECB加密后的密文
        //String decStr=decrypt(str,"123");
        String decStr=decrypt(str,"123\0\0\0\0\0\0\0\0\0\0\0\0\0");//用\0补齐不够的位数
        System.out.println(decStr);

    }