mcrypt_decrypt

(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

mcrypt_decryptBelirtilen değiştirgelerle şifreli bir metnin şifresini çözer

Açıklama

string mcrypt_decrypt ( string $şifre , string $anahtar , string $veri , string $kip [, string $iv ] )

Belirtilen verinin şifresini çözer ve şifrelenmemiş dizgeyi döndürür.

Değiştirgeler

şifre

MCRYPT_şifre_adı sabitlerinden biri veya bir dizge olarak bir algoritma ismi.

key

Veriyi şifrelemekte kullanılan anahtar. Gereken anahtar uzunluğundan kısaysa dolgu olarak "\0" karakteri kullanılır.

data

Belirtilen şifre ve kip ile şifresi çözülecek veri. Verinin küme boyunun katları uzunlukta olmasını sağlamak için dolgu olarak "\0" karakteri kullanılır.

mode

MCRYPT_kip_adı sabitlerinden biri veya bir dizge olarak şunlardan biri: "ecb", "cbc", "cfb", "ofb", "nofb", "stream".

iv

CBC, CFB, OFB kiplerini ve STREAM kipindeki bazı algoritmaları ilklendirmek için kullanılan ilklendirme vektörü (IV). Bir IV belirtmezseniz tüm baytları "\0" karakterlerinden oluşan bir dizge kullanılır.

Dönen Değerler

Şifresi çözülmüş veriyi bir dizge olarak döndürür.

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User Contributed Notes 8 notes

up
39
eddiec at stararcher dot com
12 years ago
It appears that mcrypt_decrypt pads the *RETURN STRING* with nulls ('\0') to fill out to n * blocksize.  For old C-programmers, like myself, it is easy to believe the string ends at the first null.  In PHP it does not:

    strlen("abc\0\0") returns 5 and *NOT* 3
    strcmp("abc", "abc\0\0") returns -2 and *NOT* 0

I learned this lesson painfully when I passed a string returned from mycrypt_decrypt into a NuSoap message, which happily passed the nulls along to the receiver, who couldn't figure out what I was talking about.

My solution was:
<?php
    $retval
= mcrypt_decrypt( ...etc ...);
   
$retval = rtrim($retval, "\0");     // trim ONLY the nulls at the END
?>
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4
pnz dot r00t at yandex dot ru
1 year ago
When i using this function i find some problem, with adding additional binary symbols in decode message.
$sDecrypt – «2433091»
$sDecrypt strlen – 16 (before trim)
$sDecrypt – «2433091»
$sDecrypt strlen – 7 (after trim)
At local PC this problem solved by using trim/trim, but if I send my encrypt message to sever, and try encrypt them, I see that my message is not 16 symbols, as it was in my local pc, it is 32 sybmols, after encode. And trim function not working. I look at symbols code and what I see
    50
    52
    51
    51
    48
    57
    49
    0
    0
    0
    0
    0
    0
    0
    0
    0
    10
    158
    112
    183
    154
    27
    95
    85
    42
    35
    95
    54
    227
    41
    179
    77
After “tabulation symbols” I get some junk symbols, and  I solve this problems like this.
After mcrypt_decrypt I use this code
$plaintext_dec = substr($plaintext_dec, 0, strpos($plaintext_dec, "\0"));
I think it is not best resolution for this problem, but I solve my problem :)
up
9
david at sickmiller dot com
9 years ago
If you happen to be decrypting something encrypted in ColdFusion, you'll discover that its encrypt function apparently pads the plaintext with ASCII 4, the "end of transmission" character.

Building on eddiec's code, you can remove both nulls and EOTs with this:

<?php
    $retval
= mcrypt_decrypt( ...etc ...);
   
$retval = rtrim($retval, "\0\4");     // trim ONLY the nulls and EOTs at the END
?>
up
7
beltrachi
6 years ago
Caution, MCRYPT_RIJNDAEL_256 is not equivalent to AES_256.

The way to make RIJNDAEL be decrypted from AES with openssl is to use MCRYPT_RIJNDAEL_128 and padd the string to encrypt before encrypting with the follwing function:

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

On the decryption, the choosing of AES_256 or AES_128, etc. is based on the keysize used in the crypting. In my case it was a 128bit key so I used AES_128.
up
5
evangelion207 at hotmail dot com
6 years ago
Be careful, sometimes mcrypt_decrypt return additional white spaces to the uncrypted string; use trim() for deleting them. I was like 2 hours searching the error and it was that..
up
1
gmmarco at outlook dot my
18 days ago
Look at http://php.net/manual/en/function.openssl-decrypt.php for a replacement.

Supports PHP 5 >= 5.3.0, PHP 7
up
-1
Anonymous
7 years ago
To remove PKCS7 padding:

<?php
    $decrypted
= mdecrypt_generic($td, base64_decode($enc_auth_token));
   
$dec_s = strlen($decrypted);
   
$padding = ord($decrypted[$dec_s-1]);
   
$decrypted = substr($decrypted, 0, -$padding);
?>
up
-18
artaxerxes2 at iname dot com
4 years ago
To decrypt data coming from MySQL's AES_ENCRYPT function:

<?php

function mysql_aes_key($key)
{
   
$new_key = str_repeat(chr(0), 16);
    for(
$i=0,$len=strlen($key);$i<$len;$i++)
    {
       
$new_key[$i%16] = $new_key[$i%16] ^ $key[$i];
    }
    return
$new_key;
}

function
aes_decrypt($encrypted,$key)
{
   
// if $encrypted is HEXed, then return it to binary
   
$encrypted = pack('H*',$encrypted);

   
$key = mysql_aes_key($key);
    return
rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_128,$key,$encrypted,MCRYPT_MODE_ECB,''),"\x00..\x1F");
}

?>

adapted from the article "Replicating MySQL AES Encryption Methods With PHP" (dated 2012-05-20) found somewhere online.
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