JAVA实现AES 解密报错Input length must be multiple of 16 when decrypting with padded cipher

加密代码

/\*\*解密
 \* @param content  待解密内容
 \* @param password 解密密钥
 \* @return
 \*/
public static byte\[\] decrypt(byte\[\] content, String password) {
        try {
                 KeyGenerator kgen = KeyGenerator.getInstance("AES");
                 kgen.init(128, new SecureRandom(password.getBytes()));
                 SecretKey secretKey = kgen.generateKey();
                 byte\[\] enCodeFormat = secretKey.getEncoded();
                 SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");            
                 Cipher cipher = Cipher.getInstance("AES");// 创建密码器
                cipher.init(Cipher.DECRYPT\_MODE, key);// 初始化
                byte\[\] result = cipher.doFinal(content);
                return result; // 加密
        } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
        } catch (NoSuchPaddingException e) {
                e.printStackTrace();
        } catch (InvalidKeyException e) {
                e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
                e.printStackTrace();
        } catch (BadPaddingException e) {
                e.printStackTrace();
        }
        return null;
}

解密代码

/\*\*解密
 \* @param content  待解密内容
 \* @param password 解密密钥
 \* @return
 \*/
public static byte\[\] decrypt(byte\[\] content, String password) {
        try {
                 KeyGenerator kgen = KeyGenerator.getInstance("AES");
                 kgen.init(128, new SecureRandom(password.getBytes()));
                 SecretKey secretKey = kgen.generateKey();
                 byte\[\] enCodeFormat = secretKey.getEncoded();
                 SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");            
                 Cipher cipher = Cipher.getInstance("AES");// 创建密码器
                cipher.init(Cipher.DECRYPT\_MODE, key);// 初始化
                byte\[\] result = cipher.doFinal(content);
                return result; // 加密
        } catch (NoSuchAlgorithmException e) {
                e.printStackTrace();
        } catch (NoSuchPaddingException e) {
                e.printStackTrace();
        } catch (InvalidKeyException e) {
                e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
                e.printStackTrace();
        } catch (BadPaddingException e) {
                e.printStackTrace();
        }
        return null;
}

解密代码

String content = "test";
String password = "12345678";
//加密
System.out.println("加密前：" + content);
byte\[\] encryptResult = encrypt(content, password);
try {
        String encryptResultStr = new String(encryptResult,"utf-8");
        //解密
        byte\[\] decryptResult = decrypt(encryptResultStr.getBytes("utf-8"),password);
        System.out.println("解密后：" + new String(decryptResult));
} catch (UnsupportedEncodingException e) {
        e.printStackTrace();
}

偶尔会报错抛出异常，

javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher

原因加密后的byte数组是不能强制转换成字符串的，换言之：字符串和byte数组在这种情况下不是互逆的；要避免这种情况，我们需要做一些修订，可以考虑将二进制数据转换成十六进制表示

解决方案

二进制转换成16进制

/\*\*将16进制转换为二进制
 \* @param hexStr
 \* @return
 \*/
public static byte\[\] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
                return null;
        byte\[\] result = new byte\[hexStr.length()/2\];
        for (int i = 0;i< hexStr.length()/2; i++) {
                int high = Integer.parseInt(hexStr.substring(i\*2, i\*2+1), 16);
                int low = Integer.parseInt(hexStr.substring(i\*2+1, i\*2+2), 16);
                result\[i\] = (byte) (high \* 16 + low);
        }
        return result;
}

16进制转换为二进制

/\*\*将16进制转换为二进制
 \* @param hexStr
 \* @return
 \*/
public static byte\[\] parseHexStr2Byte(String hexStr) {
        if (hexStr.length() < 1)
                return null;
        byte\[\] result = new byte\[hexStr.length()/2\];
        for (int i = 0;i< hexStr.length()/2; i++) {
                int high = Integer.parseInt(hexStr.substring(i\*2, i\*2+1), 16);
                int low = Integer.parseInt(hexStr.substring(i\*2+1, i\*2+2), 16);
                result\[i\] = (byte) (high \* 16 + low);
        }
        return result;
}

测试结果，问题解决

String content = "test";
String password = "12345678";
//加密
System.out.println("加密前：" + content);
byte\[\] encryptResult = encrypt(content, password);
String encryptResultStr = parseByte2HexStr(encryptResult);
System.out.println("加密后：" + encryptResultStr);
//解密
byte\[\] decryptFrom = parseHexStr2Byte(encryptResultStr);
byte\[\] decryptResult = decrypt(decryptFrom,password);
System.out.println("解密后：" + new String(decryptResult));