json_decode在已通过加密的字符串上返回NULL [英] json_decode returns NULL on string that has passed through encryption

问题描述

我正在尝试保护我的数据库的信息，标准类型的数据是JSON，我刚刚写了一些简单的 mcrypt 函数来加密和解密任何文本，在这里是：

 函数加密（$ key，$ data）{
 $ encrypted_data = mcrypt_cbc（MCRYPT_RIJNDAEL_192，$ key， $ data，MCRYPT_ENCRYPT）; 
返回base64_encode（$ encrypted_data）; 
} 
 
函数解密（$ key，$ encryptedData）{
 $ decrypt = mcrypt_cbc（MCRYPT_RIJNDAEL_192，$ key，base64_decode（$ encryptedData），MCRYPT_DECRYPT）; 
 return $ decrypt; 
} 
  

我有一个有效的JSON字符串，我已经测试了 json_decode 而不通过加密，它可以工作。但是当我加密然后解密它，然后尝试 json_decode 它只返回 NULL 。 / p>

现在我只是在一个简单的脚本中调试它，它是：

 包括（ coreFunctions.php）; 
 
 $ arr ='{number：4646464646，type：home}'; 
 
 $ key =ladida; 
 $ locked = encrypt（$ key，$ arr）; 
 
 var_dump（$ locked）; 
 var_dump（json_decode（decrypt（$ key，$ locked），true））; 
  

我有验证 / code>是 SAME 。

任何人都可以告诉我为什么会发生这种情况？

更新

我发现前后的 strlen（）是不同的。那么我如何确保在整个加密过程中保持不变，或者在完成之后修复它？

解决方案

bin2hex读取：

033303539222c2274797065223a22686f6d65227d00000000000000000000

这意味着您在解密的字符串中具有尾随NUL个字节。这是因为 mcrybt_cbc 以块方式运行。它将填充输入和输出到16（或24）个字节的倍数。 （输出有时甚至可能包含垃圾;因此长度字段通常会占用大多数加密方案/容器格式。）

在您的答案中，您可以避免使用 rtrim 解密后。或更准确地说：

  json_decode（rtrim（decrypt（$ key，$ locked），\0），true） ; 
  

I am trying to secure information on my database and the standard type of data is JSON and I just wrote some simple mcrypt functions that encrypt and decrypt any text, here they are:

function encrypt($key, $data){
    $encrypted_data = mcrypt_cbc(MCRYPT_RIJNDAEL_192, $key, $data, MCRYPT_ENCRYPT);
    return base64_encode($encrypted_data);
}

function decrypt($key, $encryptedData){
    $decrypt = mcrypt_cbc(MCRYPT_RIJNDAEL_192, $key, base64_decode($encryptedData), MCRYPT_DECRYPT);
    return $decrypt;
}

I have a valid JSON string and I've tested the json_decode without passing through encryption, and it works. But when I encrypt then decrypt it then try to json_decode it only returns NULL.

Right now I'm just debugging it in a simple script here it is:

include("coreFunctions.php");

$arr = '{"number":"4646464646","type":"home"}';

$key = "ladida";
$locked = encrypt($key, $arr);

var_dump($locked);
var_dump(json_decode(decrypt($key, $locked), true));

I have verified the output of decrypt is a the SAME as it went in.

Can anyone tell me why this is happening?

UPDATE
I've discovered the strlen() before and after is different. So how can I either make sure that it stays the same throughout the encryption process or fix it after it's done?

解决方案

bin2hex reads:
033303539222c2274797065223a22686f6d65227d00000000000000000000

That means you have trailing NUL bytes in the decrypted string. This happens because the mcrybt_cbc operates block-wise. It'll fill up input and output to multiples of 16 (or 24) bytes to do so. (The output might sometimes even contain garbage; hencewhy a length field often occampanies most encryption schemes / container formats.)

In your ase you can get away with applying rtrim after the decryption. Or more exactly:

 json_decode(rtrim(decrypt($key, $locked), "\0"), true);

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