Beispiele

Mcrypt can be used to encrypt and decrypt using the above mentioned ciphers. If you linked against libmcrypt-2.2.x, the four important mcrypt commands (mcrypt_cfb(), mcrypt_cbc(), mcrypt_ecb(), and mcrypt_ofb()) can operate in both modes which are named MCRYPT_ENCRYPT and MCRYPT_DECRYPT, respectively.

Beispiel #1 Encrypt an input value with TripleDES under 2.2.x in ECB mode


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

$encrypted_data = mcrypt_ecb (MCRYPT_3DES, $key, $input, MCRYPT_ENCRYPT);
?>

This example will give you the encrypted data as a string in $encrypted_data.

If you linked against libmcrypt 2.4.x or 2.5.x, these functions are still available, but it is recommended that you use the advanced functions.

Beispiel #2 Encrypt an input value with TripleDES under 2.4.x and higher in ECB mode


<?php
    $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);
?>

This example will give you the encrypted data as a string in $encrypted_data. For a full example see mcrypt_module_open().

2 BenutzerBeiträge:
- Beiträge aktualisieren...

ivoras at gmail dot com
30.08.2010 15:36


Note that there can be standard padding in block modes:



http://www.di-mgt.com.au/cryptopad.html

jizz @ Nowhere
1.07.2008 9:36


Ok after having a problem using triple des with .net/visual basic with php I think this could help someone:



Visual Basic 9 with .net 2.0

Encrypting as a stream into the IO/Memory as bytes

Then they get converted back after encryption 



I wanted to use base64 encoding to store the VB encryption

The problem I found was ... 



I could En/Decrypt within VB and PHP just fine 

But when I tried to encrypt one in VB and decrypt in PHP

I got the wrong values with the mcrypt function alone



I found that at least with VB9 that the stream encryption uses a UTF char that is the value for how many missing bytes left in the 8 bit stream.



So if you encrypt 1234 it will add chr(4) four times (the amount of missing bytes)

In php use chr otherwise most browsers/client cant read it.

Im not good at explaining things but the php code I figured out is below.



It will find the missing bytes on input as visual basic does

and replace as needed. For both encryption and decryption.



Example is triple_des and cbc with self key and iv for storing in base64



$key = "E4HD9h4DhS23DYfhHemkS3Nf";// 24 bit Key

$iv = "fYfhHeDm";// 8 bit IV

$input = "Text to encrypt";// text to encrypt

$bit_check=8;// bit amount for diff algor.



$str= encrypt($input,$key,$iv,$bit_check);

echo "Start: $input - Excrypted: $str - Decrypted: ".decrypt($str,$key,$iv,$bit_check);



function encrypt($text,$key,$iv,$bit_check) {

$text_num =str_split($text,$bit_check);

$text_num = $bit_check-strlen($text_num[count($text_num)-1]);

for ($i=0;$i<$text_num; $i++) {$text = $text . chr($text_num);}

$cipher = mcrypt_module_open(MCRYPT_TRIPLEDES,'','cbc','');

mcrypt_generic_init($cipher, $key, $iv);

$decrypted = mcrypt_generic($cipher,$text);

mcrypt_generic_deinit($cipher);

return base64_encode($decrypted);

}



function decrypt($encrypted_text,$key,$iv,$bit_check){

$cipher = mcrypt_module_open(MCRYPT_TRIPLEDES,'','cbc','');

mcrypt_generic_init($cipher, $key, $iv);

$decrypted = mdecrypt_generic($cipher,base64_decode($encrypted_text));

mcrypt_generic_deinit($cipher);

$last_char=substr($decrypted,-1);

for($i=0;$i<$bit_check-1; $i++){

    if(chr($i)==$last_char){

        

        

        

        $decrypted=substr($decrypted,0,strlen($decrypted)-$i);

        break;

    }

}

return $decrypted;

}

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