Mcrypt Problems

[Pneumatus®]

I have tried to follow the instructions in the PHP manual but have been
unable to get things working properly myself. The following script works
fine for me:
<?php
/* Open the cipher */
$td = mcrypt_module_o pen ('rijndael-256', '', 'ofb', '');

/* Create the IV and determine the keysize length */
$iv = mcrypt_create_i v (mcrypt_enc_get _iv_size($td),
MCRYPT_DEV_RAND OM);
$ks = mcrypt_enc_get_ key_size ($td);

/* Create key */
$key = substr (md5 ('very secret key'), 0, $ks);

/* Intialize encryption */
mcrypt_generic_ init ($td, $key, $iv);

/* Encrypt data */
$encrypted = mcrypt_generic ($td, 'This is very important data');

/* Terminate encryption handler */
mcrypt_generic_ deinit ($td);

/* Initialize encryption module for decryption */
mcrypt_generic_ init ($td, $key, $iv);

/* Decrypt encrypted string */
$decrypted = mdecrypt_generi c ($td, $encrypted);

/* Terminate decryption handle and close module */
mcrypt_generic_ deinit ($td);
mcrypt_module_c lose ($td);

/* Show string */
echo trim ($decrypted)."\ n";
?>

But, the encryption and decryption are all done in one shot - I've tried
to make two functions:

<?php
function do_encrypt ($string, $key) {
/* Open the cipher */
$td = mcrypt_module_o pen ('rijndael-256', '', 'ofb', '');

/* Create the IV and determine the keysize length */
$iv = mcrypt_create_i v (mcrypt_enc_get _iv_size($td),
MCRYPT_DEV_RAND OM);
$ks = mcrypt_enc_get_ key_size ($td);

/* Create key */
$key = substr (md5 ($key), 0, $ks);

/* Intialize encryption */
mcrypt_generic_ init ($td, $key, $iv);

/* Encrypt data */
$encrypted = mcrypt_generic ($td, 'This is very important data');

/* Terminate decryption handle and close module */
mcrypt_generic_ deinit ($td);
mcrypt_module_c lose ($td);

return $encrypted;

}

function do_decrypt ($string, $key) {
/* Open the cipher */
$td = mcrypt_module_o pen ('rijndael-256', '', 'ofb', '');

/* Create the IV and determine the keysize length */
$iv = mcrypt_create_i v (mcrypt_enc_get _iv_size($td),
MCRYPT_DEV_RAND OM);
$ks = mcrypt_enc_get_ key_size ($td);

/* Create key */
$key = substr (md5 ($key), 0, $ks);

/* Initialize encryption module for decryption */
mcrypt_generic_ init ($td, $key, $iv);

/* Decrypt encrypted string */
$decrypted = mdecrypt_generi c ($td, $string);

/* Terminate decryption handle and close module */
mcrypt_generic_ deinit ($td);
mcrypt_module_c lose ($td);

return $decrypted;
}

$encrypted_stri ng = do_encrypt("my string", "my key");

echo "The encrypted string is: " . $encrypted_stri ng . "<br>\n";

$decrypted_stri ng = do_decrypt($enc rypted_string, "my key");

echo "The decrypted string is: " . $decrypted_stri ng . "<br>\n";
?>

The thing is, the decrypted string never comes out as "my string"...

Can anyone help.

--
Pneu.....
http://www.pneumatus.co.uk
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