mdecrypt_generic

Decrypt data (PHP 4 >= 4.0.2, PHP 5)
string mdecrypt_generic ( resource td, string data )

Example 1304. mdecrypt_generic() example

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<?php

    /* Data */

    $key = 'this is a very long key, even too long for the cipher';

    $plain_text = 'very important data';

   

    /* Open module, and create IV */ 

    $td = mcrypt_module_open('des', '', 'ecb', '');

    $key = substr($key, 0, mcrypt_enc_get_key_size($td));

    $iv_size = mcrypt_enc_get_iv_size($td);

    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);


    /* Initialize encryption handle */

    if (mcrypt_generic_init($td, $key, $iv) != -1) {


        /* Encrypt data */

        $c_t = mcrypt_generic($td, $plain_text);

        mcrypt_generic_deinit($td);


        /* Reinitialize buffers for decryption */

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

        $p_t = mdecrypt_generic($td, $c_t);


        /* Clean up */

        mcrypt_generic_deinit($td);

        mcrypt_module_close($td);

    }


    if (strncmp($p_t, $plain_text, strlen($plain_text)) == 0) {

        echo "ok\n";

    } else {

        echo "error\n";

    }
?>

Code Examples / Notes » mdecrypt_generic

drew

On Win32 systems with PHP 5, you must use the newer libmcrypt.dll file, otherwise mdecrypt_generic will not work.

php

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.

silvan

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); } ?>

robbie

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.

jon@jonroig dot com

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 " "; $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); ?>

Change Language

mcrypt_cbc
mcrypt_cfb
mcrypt_create_iv
mcrypt_decrypt
mcrypt_ecb
mcrypt_enc_get_algorithms_name
mcrypt_enc_get_block_size
mcrypt_enc_get_iv_size
mcrypt_enc_get_key_size
mcrypt_enc_get_modes_name
mcrypt_enc_get_supported_key_sizes
mcrypt_enc_is_block_algorithm_mode
mcrypt_enc_is_block_algorithm
mcrypt_enc_is_block_mode
mcrypt_enc_self_test
mcrypt_encrypt
mcrypt_generic_deinit
mcrypt_generic_end
mcrypt_generic_init
mcrypt_generic
mcrypt_get_block_size
mcrypt_get_cipher_name
mcrypt_get_iv_size
mcrypt_get_key_size
mcrypt_list_algorithms
mcrypt_list_modes
mcrypt_module_close
mcrypt_module_get_algo_block_size
mcrypt_module_get_algo_key_size
mcrypt_module_get_supported_key_sizes
mcrypt_module_is_block_algorithm_mode
mcrypt_module_is_block_algorithm
mcrypt_module_is_block_mode
mcrypt_module_open
mcrypt_module_self_test
mcrypt_ofb
mdecrypt_generic

mdecrypt_generic

Decrypt data (PHP 4 >= 4.0.2, PHP 5) string mdecrypt_generic ( resource td, string data )

Example 1304. mdecrypt_generic() example

Code Examples / Notes » mdecrypt_generic

Change Language

Decrypt data (PHP 4 >= 4.0.2, PHP 5)
string mdecrypt_generic ( resource td, string data )