mcrypt_module_open

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

mcrypt_module_openKullanılacak kipi ve algoritma modülünü açar

Açıklama

resource mcrypt_module_open ( string $algoritma , string $algoritma_dizini , string $kip , string $kip_dizini )

Kullanılacak kipi ve algoritma modülünü açar. Algoritma doğrudan ismiyle belirtilebileceği gibi ("twofish" gibi), MCRYPT_şifre_adı sabitlerinden biri de belirtilebilir. Modülü kapatmak için mcrypt_module_close() kullanılır.

Değiştirgeler

algoritma

Kullanılacak algoritma.

algoritma_dizini

algorithm_dizini ve mode_dizini şifreleme modüllerinin yerlerini belirtmek için kullanılır. Bir dizin yerine boş bir dizge belirtirseniz mcrypt.algorithms_dir veya mcrypt.modes_dir php.ini yönergelerinin değerleri kullanılır. Bunlar atanmamışsa libmcrypt derlenirken kullanılan öntanımlı dizinler kullanılır (genellikle /usr/local/lib/libmcrypt).

kip

Kullanılacak kip.

kip_dizini

Dönen Değerler

Bir hata durumunda FALSE yoksa bir şifreleme tanıtıcısı döndürür.

Örnekler

Örnek 1 - mcrypt_module_open() örnekleri

<?php
    $şt 
mcrypt_module_open(MCRYPT_DES'',
        
MCRYPT_MODE_ECB'/usr/lib/mcrypt-modes');

    
$şt mcrypt_module_open('rijndael-256''''ofb''');
?>

Yukarıdaki örnekteki ilk satır öntanımlı dizindeki DES şifre modülünü ve /usr/lib/mcrypt-modes dizinindeki EBC kip modülünü açacaktır. İkinci örnekte şifre ve kip için isimleri kullanılmaktadır. Bu örnek sadece eklenti, libmcrypt 2.4.x veya 2.5.x desteğiyle derlenmişse çalışacaktır.

Örnek 2 - Şifreleme için mcrypt_module_open() kullanımı

<?php
    
/* Şifre modülünü açalım */
    
$şt mcrypt_module_open('rijndael-256''''ofb''');

    
/* IV'yi oluşturup anahtar uzunluğunu belirleyelim.
       Windows'ta bunun yerine MCRYPT_RAND kullanın */
    
$iv mcrypt_create_iv(mcrypt_enc_get_iv_size($şt), MCRYPT_DEV_RANDOM);
    
$ks mcrypt_enc_get_key_size($şt);

    
/* Anahtarı oluşturalım */
    
$tuz substr(md5('çok gizli anahtar'), 0$ks);

    
/* Şifreleme işlemini ilklendirelim */
    
mcrypt_generic_init($şt$tuz$iv);

    
/* Veriyi şifreleyelim */
    
$şifreli mcrypt_generic($şt'Bu çok önemli bir veridir.');

    
/* Şifre tanıtıcısını sonlandıralım */
    
mcrypt_generic_deinit($şt);

    
/* Şifreleme modülünü şifre çözmek için ilklendirelim */
    
mcrypt_generic_init($şt$tuz$iv);

    
/* Verinin şifresini çözelim */
    
$şifresiz mdecrypt_generic($şt$şifreli);

    
/* Şifre çözme tanıtıcısını sonlandıralım ve modülü kapatalım */
    
mcrypt_generic_deinit($şt);
    
mcrypt_module_close($şt);

    
/* Dizgeyi gösterelim */
    
echo trim($şifresiz) . "\n";
?>

Ayrıca Bakınız

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User Contributed Notes 7 notes

up
5
dinamic at gmail dot com
10 years ago
Also it should be pointed that md5() and/or sha1() should not be used while forming your key for the mcrypt. This is so because hex encoding uses a set of only 16 characters [0-9a-f], which is equivalent to 4 bits, and thus halve the strength of your encryption: 4 x 32 = 128-bit.

I have re-wrote the example shown, so here is my suggestion to get real 256-bit encryption:

<?php
$key1
= "this is a secret key";
$key2 = "this is the second secret key";
$input = "Let us meet at 9 o'clock at the secret place.";
$length = strlen($input);

   
/* Open the cipher */
   
$td = mcrypt_module_open('rijndael-256', '', 'cbc', '');

   
/* Create the IV and determine the keysize length, use MCRYPT_RAND
     * on Windows instead */
   
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
   
$ks = mcrypt_enc_get_key_size($td);

   
/* Create key */
   
$key1 = md5($key1);
   
$key2 = md5($key2);

   
$key = substr($key1, 0, $ks/2) . substr(strtoupper($key2), (round(strlen($key2) / 2)), $ks/2);

   
$key = substr($key.$key1.$key2.strtoupper($key1),0,$ks);

   
/* Intialize encryption */
   
mcrypt_generic_init($td, $key, $iv);

   
/* Encrypt data */
   
$encrypted = mcrypt_generic($td, $input);

   
/* Terminate encryption handler */
   
mcrypt_generic_deinit($td);

   
/* Initialize encryption module for decryption */
   
mcrypt_generic_init($td, $key, $iv);

   
/* Decrypt encrypted string */
   
$decrypted = mdecrypt_generic($td, $encrypted);

   
/* Terminate decryption handle and close module */
   
mcrypt_generic_deinit($td);
   
mcrypt_module_close($td);

   
/* Show string */
   
echo "Text: ".substr($decrypted,0,$length) . "<br>";
    echo
"Encoded: ".$encrypted ."<br>";
    echo
"<br>key1: $key1 <br>key2: $key2<br>created key: $key";
?>
up
1
royconejo
8 years ago
about the previous comments on hex formatting and capitalization as a way to improve the key:

this would seem pretty obvious, but it is a choice to be limited to only hex characters ([0-9a-z]); you can get the original RAW output from md5() or sha1() and not the default readable hex formatting.

the result of a raw output will be 16 o 20 (depending on the hash function being used) series of chars in the range 0-255. way better than [0-9a-z] and even [0-9a-zA-Z].

16 or 20 is generally lower than the maximum key lenght ($ks in the example), but you can append two or more keys together:

<?php
$human_key1
= 'something very secret';
$human_key2 = 'something else very secret';

// 40 bytes binary key using two "human readable" keys and sha1.
$bigger_binary_key = sha1($human_key1, true) . sha1($human_key2, true);

// then just use it as you would (extract taken from the example)
$key = substr($bigger_binary_key, 0, $ks);
?>

... or you can automatically split one large "human key" into two or more parts, hash those parts with sha1 (raw output!) and merge them together again (in original order or rearrange, salt, transform them as you like) to get a binary key of 40, 60, 80 or more chars depending on the number of parts the secret key has been splitted =)
up
1
Mark
5 years ago
for errors like
' mcrypt_module_open(): Could not open encryption module in '

Make sure you're using the right name. The page giving the list of ciphers is NOT the right way to say each cipher (shown here http://www.php.net/manual/en/mcrypt.ciphers.php).

In order to see what ones are supported, try phpinfo(); and look under mcrypt to find something like this

mcrypt support => enabled
mcrypt_filter support => enabled
Version => 2.5.8
Api No => 20021217
Supported ciphers => cast-128 gost rijndael-128 twofish arcfour cast-256 loki97 rijndael-192 saferplus wake blowfish-compat des rijndael-256
serpent xtea blowfish enigma rc2 tripledes
Supported modes => cbc cfb ctr ecb ncfb nofb ofb stream
up
0
Anonymous
1 year ago
Follow up to anonymous with Windows' mcrypt_module_open() errors:

<?php
$M
= mcrypt_list_modes();
$A = mcrypt_list_algorithms();
foreach (
$M as $m)
    foreach (
$A as $a) {
       
$t = @mcrypt_module_open($a,'',$m,'');
        print
"$m, $a = ";
        print (
$t)?"ok":"nope";
        print
"<br>";
    }
?>

This will show that not all modes work with all algorithmns. Cygwin also has no 'libmcrypt.dll' and it too will work with only some combinations.

(First tries just happened to be one of the ones that did not work!)
up
0
lehmann*at*arcor-so.net
8 years ago
Keep in mind that the mcrypt functions do not implement padding like e.g. pkcs#5. This causes the problem with zero bytes at the end and the sting cannot be correctly decoded in other environments.

For an example how to add pkcs 5 padding, see ref.mcrypt.php
up
-1
Anonymous
14 years ago
Doing a trim($decrypted) will remove the null padding that may occur as a result of decryption.

The problem is if you're encrypting something like a MSWord document which can commonly end with nulls. The result $decrypted will be smaller than the original cleartext - which will then fail to open in MSOffice.

To get around this, make sure you store the length of the original cleartext, and when you decrypt it, do:

$decrypted = substr(mdecrypt_generic($td, $encrypted), 0, $originalLength);
up
-2
ash
9 years ago
A slight improvement of dinamic's function to create a key:

I think the weak point is that capitals are always used in the same part of the string. The following code capitalizes random characters of the string, making the key less predictable:

<?php
$key
= substr($key1, 0, $ks/2) . substr($key2, (round(strlen($key2) / 2)), $ks/2);
$key = substr($key.$key1.$key2.$key1,0,$ks);

$buffer = str_split($key);

$limit = count($buffer)-1;
srand((float)microtime() * 1000000);

$end = rand(0, $limit);
$a = 0;

// replace random chars with capitals
while ($a < $end) {   
    list(
$usec, $sec) = explode(' ', microtime());
       
$seed = ((float)$sec) + ((float) $usec * 100000);
   
mt_srand($seed);
   
   
$index = mt_rand(0,$limit);
   
   
$buffer[$index] = strtoupper($buffer[$index]);
   
$a++;
}

$key = join('', $buffer);
?>
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