php5.6 的mcrypt_encrypt 函数可以和5.5.9的行为一样

php5.5.9

-----------------------
$output = "test  php !!"

$key = "abcd123456789";

$output = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $output, MCRYPT_MODE_CBC);

$output = bin2hex($output);

echo $output;

 

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php5.6 之后，mcrypt_encrypt 必须要 带 第五个参数 $iv,  但是加密出来的结果也可以和5.5的行为一样

1. php5.6 中 key 必须要8，16，32个字符；（之前的只有15个字符，php5.5其实是自动填 \0 ）

2. php5.6 中 iv 必须要 ； （之前的版本， php5.5应该是默认填 16个\0 (至于是8个， 还是16个，32个，这个是和前面的key的长度有关的！)）；

所有，基于以上的原因，便有了下面php5.6对应的代码：

--------------------------------------------------------

 

$output = "test  php !!"

$key = "abcd123456789"."\0\0\0";
$iv = str_repeat("\0", 16);
$output = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key, $output, MCRYPT_MODE_CBC, $iv);

$output = bin2hex($output);

echo $output;

-------------------------------------------

Found the answer in case anyone need

$ivSize = 8;
$iv = str_repeat("\0", $ivSize);

$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_CBC, $iv));

Pass a 5th parameter manually which the earlier version was doing on its own!

--------------------------------------------------------------

参考：https://stackoverflow.com/questions/30475946/mcrypt-encrypt-not-working-properly-on-php-5-6-9/30477958#30477958

mcrypt_encrypt not working properly on PHP 5.6.9

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I have the following code which worked fine on PHP 5.5.9.

function index()
{
    echo $this->encryptText_3des('TEST','JHHKJH9879');
}

function encryptText_3des($plainText, $key) {
    $key = hash("md5", $key, TRUE);
    for ($x=0;$x<8;$x++) {
        $key = $key.substr($key, $x, 1);
    }
    $padded = $this->pkcs5_pad($plainText,
    mcrypt_get_block_size(MCRYPT_3DES, MCRYPT_MODE_CBC));
    $encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_CBC));
    return $encrypted;
}

function pkcs5_pad ($text, $blocksize)
{
    $pad = $blocksize - (strlen($text) % $blocksize);
    return $text . str_repeat(chr($pad), $pad);
}

The encryption was happening fine.But in 5.6.9, the in the PHP doc of mcrypt_encrypt, they mention that

Invalid key and iv sizes are no longer accepted. mcrypt_encrypt() will now throw a warning and return FALSE if the inputs are invalid. Previously keys and IVs were padded with '\0' bytes to the next valid size.

How will I modify my current code with the fifth parameter without altering the encryption algorithm?

I tried

$iv_size = mcrypt_get_iv_size(MCRYPT_3DES, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);

and given $iv as fifth parameter.

But it didn't work out. The encryption was different from the earlier one.

php encryption mcrypt php-5.6

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edited May 27 '15 at 9:10

Artjom B.

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asked May 27 '15 at 7:32

Saritha Nair

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3 Answers

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Don't emulate old PHP versions weak behaviour for initializing IV.

Use mcrypt_create_iv().

They removed the auto zero-byte iv for a reason.

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answered May 27 '15 at 9:10

Daniel W.

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•  
  While I agree that a random IV should be used, it may not be applicable to the OPs case, because they already have a library full of ciphertexts which must be compatible. – Artjom B. May 27 '15 at 9:13
•  
  @ArtjomB. good point, to ensure decryption of "legacy" ciphertexts, the "old" iv must be used.. – Daniel W. May 27 '15 at 9:14
• 1
  Make sure you use MCRYPT_DEV_URANDOM too! – Scott Arciszewski Aug 11 '15 at 23:16

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2

Found the answer in case anyone need

$ivSize = 8;
$iv = str_repeat("\0", $ivSize);

$encrypted = base64_encode(mcrypt_encrypt(MCRYPT_3DES, $key, $padded, MCRYPT_MODE_CBC, $iv));

Pass a 5th parameter manually which the earlier version was doing on its own!

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edited May 27 '15 at 9:11

Artjom B.

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answered May 27 '15 at 8:52

Saritha Nair

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