[PHP] web-based and command line mcrypting and back again

[Gary C. New]

I am trying to figure out how to encrypt data using the web-based php 
mcrypt function and then decrypt it using the command line (cli) mcrypt 
binary, and vica-versa.

I cannot seem to get the same encrypted output for the same data, 
between the two methods.  I've tried to ensure I am using the same 
algorithms and modes for both methods by testing the mcrypt_enc_get_* 
functions.  I think the problem may lie in the way both methods are 
being seeded.

Web-Based PHP Example:

$key = 'test';
$data[] = 'abcdefghijklmnopqrstuvwxyz';
$m = 0;
foreach ($data as $dt)
{
   $td = mcrypt_module_open('tripledes', '', 'ecb', '');
   $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
   mcrypt_generic_init($td, $key, $iv);
   $CRYPT[$m] = mcrypt_generic($td, $dt);
/*
   echo mcrypt_enc_get_algorithms_name($td);
   echo mcrypt_enc_get_block_size($td);
   echo mcrypt_enc_get_iv_size($td);
   echo mcrypt_enc_get_key_size($td);
   echo mcrypt_enc_get_modes_name($td);
   echo mcrypt_enc_get_supported_key_sizes($td);
   echo mcrypt_enc_is_block_algorithm_mode($td);
   echo mcrypt_enc_is_block_algorithm($td);
   echo mcrypt_enc_is_block_mode($td);
   echo mcrypt_enc_self_test($td);
*/
   $DECRYPT[$m] = mdecrypt_generic($td, $dt);
   mcrypt_generic_deinit($td);
   mcrypt_module_close($td);
   echo crypt_ . base64_encode($CRYPT[$m]) . _br /\n;
   echo decrypt_ . base64_decode(rtrim($DECRYPT[$m])) . _br /\n;
   $m++;
}
Note:  I believe it is the line where the $iv variable is being set that 
is causing the issue and/or I cannot reproduce the same seeding using 
the command line options.

Command Line Example:

echo abcdefghijklmnopqrstuvwxyz | mcrypt -Fb -m ecb -a tripledes | 
encode-base64

echo  | decode-base64 | mcrypt -dFb -m ecb -a tripledes

I would appreciate any comments or suggestions.

Respectfully,

Gary

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Re: [PHP] web-based and command line mcrypting and back again

[Tom Rogers]

Hi,

Tuesday, January 6, 2004, 8:48:17 PM, you wrote:
GCN I am trying to figure out how to encrypt data using the web-based php
GCN mcrypt function and then decrypt it using the command line (cli) mcrypt
GCN binary, and vica-versa.

GCN I cannot seem to get the same encrypted output for the same data,
GCN between the two methods.  I've tried to ensure I am using the same
GCN algorithms and modes for both methods by testing the mcrypt_enc_get_*
GCN functions.  I think the problem may lie in the way both methods are
GCN being seeded.

GCN Web-Based PHP Example:

GCN $key = 'test';
GCN $data[] = 'abcdefghijklmnopqrstuvwxyz';
GCN $m = 0;

GCN foreach ($data as $dt)
GCN {
GCN $td = mcrypt_module_open('tripledes', '', 'ecb', '');
GCN $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
GCN mcrypt_generic_init($td, $key, $iv);
GCN $CRYPT[$m] = mcrypt_generic($td, $dt);

GCN /*
GCN echo mcrypt_enc_get_algorithms_name($td);
GCN echo mcrypt_enc_get_block_size($td);
GCN echo mcrypt_enc_get_iv_size($td);
GCN echo mcrypt_enc_get_key_size($td);
GCN echo mcrypt_enc_get_modes_name($td);
GCN echo mcrypt_enc_get_supported_key_sizes($td);
GCN echo mcrypt_enc_is_block_algorithm_mode($td);
GCN echo mcrypt_enc_is_block_algorithm($td);
GCN echo mcrypt_enc_is_block_mode($td);
GCN echo mcrypt_enc_self_test($td);
GCN */

GCN $DECRYPT[$m] = mdecrypt_generic($td, $dt);
GCN mcrypt_generic_deinit($td);
GCN mcrypt_module_close($td);

GCN echo crypt_ . base64_encode($CRYPT[$m]) . _br /\n;
GCN echo decrypt_ . base64_decode(rtrim($DECRYPT[$m])) . _br /\n;

GCN $m++;
GCN }

GCN Note:  I believe it is the line where the $iv variable is being set that
GCN is causing the issue and/or I cannot reproduce the same seeding using
GCN the command line options.


GCN Command Line Example:

GCN echo abcdefghijklmnopqrstuvwxyz | mcrypt -Fb -m ecb -a tripledes |
GCN encode-base64

GCN echo  | decode-base64 | mcrypt -dFb -m ecb -a tripledes


GCN I would appreciate any comments or suggestions.

GCN Respectfully,


GCN Gary


try setting the iv to all 0's
$iv = 0;
$iv = pack(a.mcrypt_enc_get_iv_size($td),$iv);

-- 
regards,
Tom

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