note 63484 deleted from function.mcrypt-module-open by bjori
| From: | bjori@php.net | Date: | Wed, 22 Mar 2006 20:45:38 +0000 |
| Subject: | note 63484 deleted from function.mcrypt-module-open by bjori | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-106370@lists.php.net to get a copy of this message | ||
Note Submitter:
Reason: bad code
----
I needed to have a way of encrypting and decrypting information in a database, and the mcrypt
library seemed like the best way to do that. After reading the documentation and examples I created
two functions. One was to encrypt data and the other was to decrypt data. Here is basically what I
wrote at first:
function myencrypt($data, $key)
{
$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
$ks = mcrypt_enc_get_key_size($td);
mcrypt_generic_init($td, $key, $iv);
$encrypted = mcrypt_generic($td, $data);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return base64_encode($encrypted);
}
function mydecrypt($encrypted_data, $key)
{
$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_DEV_RANDOM);
$ks = mcrypt_enc_get_key_size($td);
mcrypt_generic_init($td, $key, $iv);
$decrypted = mdecrypt_generic($td, base64_decode( $encrypted_data ));
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return $decrypted;
}
After writing the functions I began to test them. These functions would run well for about the
first 50-100 times, and then pause for a while (I imagine that the program was blocked waiting for a
resource) and then run 50-100 more and pause again. I think the problem is that the function was
calling mcrypt_module_open each time it ran and that must make a system call to allocate a file
handle, or some kind of resource handle. To fix this I replaced the functions with the following:
$__td = mcrypt_module_open('tripledes', '', 'ecb', '');
$__iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($__td), MCRYPT_DEV_RANDOM);
$__ks = mcrypt_enc_get_key_size($__td);
function myencrypt($data, $key)
{
global $__td, $__iv, $__ks;
mcrypt_generic_init($__td, $key, $__iv);
$encrypted = mcrypt_generic($__td, $data);
mcrypt_generic_deinit($__td);
return base64_encode($encrypted);
}
function mydecrypt($encrypted_data, $key)
{
global $__td, $__iv, $__ks;
mcrypt_generic_init($__td, $key, $__iv);
$decrypted = mdecrypt_generic($__td, base64_decode($encrypted_data));
mcrypt_generic_deinit($__td);
return $decrypted;
}
Since it uses a global handle to the mcrypt module, it never has to wait for the system to return a
handle. Benchmarked these new functions with a test script that did 10000 encrypts and decrypts and
it ran perfectly.
For those of you that don't like to allocate something and never de-allocate it, rest assured
that PHP will clean it up. One of the beauties of PHP.