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mdecrypt_generic

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

mdecrypt_genericVerinin şifresini çözer

Uyarı

Bu işlevin kullanımı PHP 7.1.0 itibariyle ÖNERİLMEMEKTE olup PHP 7.2.0'da tamamen KALDIRILMIŞTIR. Bu işleve kesinlikle güvenilmemelidir.

Açıklama

mdecrypt_generic(resource $şt, string $veri): string

Belirtilen verinin şifresini çözer. Şifresi çözülürken verinin sonuna eklenen baytlar yüzünden dönen dizge şifrelenmemiş dizgeden daha uzundur.

Bağımsız Değişkenler

şt

mcrypt_module_open() tarafından döndürülmüş bir şifreleme tanıtıcısı.

data

Şifrelenmiş veri.

Dönen Değerler

Şifresi çözülmüş veri döner.

Örnekler

Örnek 1 - mdecrypt_generic() örneği

<?php
/* Veri */
$tuz = 'Bu anahtar bu şifre için bile gereğinden uzun bir anahtar';
$veri = 'çok önemli veri';

/* Modülü açıp bir İV üretelim */
$şt = mcrypt_module_open('des', '', 'ecb', '');
$tuz = substr($tuz, 0, mcrypt_enc_get_key_size($şt));
$iv_boyu = mcrypt_enc_get_iv_size($şt);
$iv = mcrypt_create_iv($iv_boyu, MCRYPT_RAND);

/* Şifreleme tanıtıcısını ilklendirelim */
if (mcrypt_generic_init($şt, $tuz, $iv) != -1) {

/* Veriyi şifreleyelim */
$şifreli_veri = mcrypt_generic($şt, $veri);
mcrypt_generic_deinit($şt);

/* Şifreyi çözmek için tamponu ilklendirelim */
mcrypt_generic_init($şt, $tuz, $iv);
$sonuç = mdecrypt_generic($şt, $şifreli_veri);

/* Temizlik */
mcrypt_generic_deinit($şt);
mcrypt_module_close($şt);
}

if (
strncmp($sonuç, $veri, strlen($veri)) == 0) {
echo
"Tamam\n";
} else {
echo
"Hata\n";
}
?>

Yukarıdaki örnekte, şifreleme öncesi veri ile şifreleme sonrası şifresi çözülmüş verinin nasıl karşılaştırılacağı gösterilmiştir. Bir verinin şifresini çözmeden önce şifreleme tamponunu mcrypt_generic_init() ile yeniden ilklendirmek çok önemlidir.

Bu işlevi çağırmadan önce, mcrypt_generic_init() işlevini bir tuz ve bir İV (ilklendirme vektörü) ile çağırarak şifreleme tanıtıcısını daima ilklendirmelisiniz. Şifreleme bittikten sonra şifreleme tamponlarını mcrypt_generic_deinit() işleviyle serbest bırakmalısınız. Bununla ilgili bir örneği mcrypt_module_open() işlevinin açıklamasında bulabilirsiniz.

Ayrıca Bakınız

add a note

User Contributed Notes 11 notes

up
6
nytro_rst at yahoo dot com
15 years ago
<?php
// Parameters:
// $text = The text that you want to encrypt.
// $key = The key you're using to encrypt.
// $alg = The algorithm.
// $crypt = 1 if you want to crypt, or 0 if you want to decrypt.

function cryptare($text, $key, $alg, $crypt)
{
$encrypted_data="";
switch(
$alg)
{
case
"3des":
$td = mcrypt_module_open('tripledes', '', 'ecb', '');
break;
case
"cast-128":
$td = mcrypt_module_open('cast-128', '', 'ecb', '');
break;
case
"gost":
$td = mcrypt_module_open('gost', '', 'ecb', '');
break;
case
"rijndael-128":
$td = mcrypt_module_open('rijndael-128', '', 'ecb', '');
break;
case
"twofish":
$td = mcrypt_module_open('twofish', '', 'ecb', '');
break;
case
"arcfour":
$td = mcrypt_module_open('arcfour', '', 'ecb', '');
break;
case
"cast-256":
$td = mcrypt_module_open('cast-256', '', 'ecb', '');
break;
case
"loki97":
$td = mcrypt_module_open('loki97', '', 'ecb', '');
break;
case
"rijndael-192":
$td = mcrypt_module_open('rijndael-192', '', 'ecb', '');
break;
case
"saferplus":
$td = mcrypt_module_open('saferplus', '', 'ecb', '');
break;
case
"wake":
$td = mcrypt_module_open('wake', '', 'ecb', '');
break;
case
"blowfish-compat":
$td = mcrypt_module_open('blowfish-compat', '', 'ecb', '');
break;
case
"des":
$td = mcrypt_module_open('des', '', 'ecb', '');
break;
case
"rijndael-256":
$td = mcrypt_module_open('rijndael-256', '', 'ecb', '');
break;
case
"xtea":
$td = mcrypt_module_open('xtea', '', 'ecb', '');
break;
case
"enigma":
$td = mcrypt_module_open('enigma', '', 'ecb', '');
break;
case
"rc2":
$td = mcrypt_module_open('rc2', '', 'ecb', '');
break;
default:
$td = mcrypt_module_open('blowfish', '', 'ecb', '');
break;
}

$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
$key = substr($key, 0, mcrypt_enc_get_key_size($td));
mcrypt_generic_init($td, $key, $iv);

if(
$crypt)
{
$encrypted_data = mcrypt_generic($td, $text);
}
else
{
$encrypted_data = mdecrypt_generic($td, $text);
}

mcrypt_generic_deinit($td);
mcrypt_module_close($td);

return
$encrypted_data;
}
?>
up
4
jakub dot lopuszanski at nasza-klasa dot pl
10 years ago
For all those of you which are "surprised" by the padding (even though it is mentioned in the description of the method) please do not just "strip away everything which I do not understand".
The approach with rtrim, rtrim "\0", removing all charcodes < 16, etc. are all wrong.
The PKCS #7 padding works just as described in RFC 5652.
To remove it, just look at the last byte of the message, and it will tell you how many bytes to remove.
For example, if the last byte is equal to \0A, then remove 10 bytes.
up
2
Ulysse
10 years ago
Based on the information provided by "jakub dot lopuszanski at nasza-klasa dot pl" that in PKCS#7, the last byte contains the number of byte to remove (see RFC 5652, part 6.3), and for those like me who like to copy paste an already-made snippet:

<?php
function unpadPKCS7($data, $blocksize)
{
$last = substr($data, -1);
return
substr($data, 0, strlen($data) - ord($last));
}
?>

Now you have no more reason to use rtrim() to remove the padding at the end of the result.
up
2
Anonymous
15 years ago
Here's a quick snippet for removing PKCS7 padding:

<?php
function unpadPKCS7($data, $blockSize) {
$length = strlen ( $data );
if (
$length > 0) {
$first = substr ( $data, - 1 );

if (
ord ( $first ) <= $blockSize) {
for(
$i = $length - 2; $i > 0; $i --)
if (
ord ( $data [$i] != $first ))
break;

return
substr ( $data, 0, $i );
}
}
return
$data;
}
?>
up
2
Peter Bailey
12 years ago
We found that sometimes the resulting padding is not null characters "\0" but rather one of several control characters.

If you know your data is not supposed to have any trailing control characters "as we did" you can strip them like so.

<?php

$data
= mdecrypt_generic( $cipher, $data );

// Strip trailing control-character padding
$data = preg_replace( "/\p{Cc}*$/u", "", $data );

?>
up
2
trashmail dot hashishin at gmail dot com
13 years ago
Whenever you need to decrypt files encrypted with dot.net (and others?) you can use the following settings:

Encryption: 'rijndael-256'
Mode: 'cbc'
Padding-Mode: Zeros
iv: "yes"

encode the data with base64 to send them to your php script
up
1
robbie [at] averill [dot] co [dot] nz
19 years ago
I have noticed that sometimes when the binary ciphertext is longer than the plaintext, the decrypted plaintext can have some little boxes/squares next to it as 'padding'. I also noticed that you can't cut and paste them to be able to edit them out, but i did find a solution.

Just call rtrim() around the string and it removes them.
up
0
Silvan
16 years ago
It is generally not recommended to just use rtrim to remove the padding.

Use rtrim($str, "\0") for strings that do not end in "\0" or store the data length during encryption.
(Although data containing "\0" sometimes gets corrupted during encryption so these types of data actually should be packed.)

For example:

<?php

function encrypt($original_data)
{
$length = strlen($original_data);
$data_to_encrypt = $length.'|'.$original_data;
// Encrypt the data including its length.
// Do not save the length unencrypted, as this could be a (minor) security risk
}

function
decrypt($cypher)
{
// Decrypt the cypher data first
// Next retrieve the original data
list($length, $padded_data) = explode('|', $decrypted_data, 2);
$original_data = substr($padded_data, 0, $length);
}

?>
up
0
php at pcwize dot com
17 years ago
Just confirming the .DLL issues. With 4.3.4 you need the older .DLL. I'm guessing any version of PHP4 needs the older .DLL. With PHP5 you need the newer one.
up
0
drew at expressdynamics dot com
18 years ago
On Win32 systems with PHP 5, you must use the newer libmcrypt.dll file, otherwise mdecrypt_generic will not work.
up
0
jon@jonroig dot com
19 years ago
Here's a bit of encrypt/decrypt code.

If you're using this on the win32 platform, BEWARE! The latest DLL (19-Jan-2004) contains a bug that keeps mdecrypt_generic from functioning. Nearly drove me over the edge... The 30-Dec-2002 version seems to work with no trouble.
<?

$key = "this is a secret key";
$input = "Let us meet at 9 o'clock at the secret place.";

$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);
$encrypted_data = mcrypt_generic($td, $input);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);

echo "Encrypt: ".$encrypted_data;

echo "<br><br>";

$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
$key = substr($key, 0, mcrypt_enc_get_key_size($td));
mcrypt_generic_init($td, $key, $iv);
$decrypted_data = mdecrypt_generic($td, $encrypted_data);
echo "Decrypt: ".$decrypted_data;
mcrypt_generic_deinit($td);
mcrypt_module_close($td);

?>
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