I Encrypt and Decrypt successfully, but when I decrypt the value, appears strange characters at the final of string "???": The initial $_POST['value'] do not have any blank space or any strange character

Any idea to solve this?

Encrypt with this:

$key='my key';
$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);    	
$id = mcrypt_generic($td, $_POST['value']);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);

Decrypt with this:

$key='my key';
$td = mcrypt_module_open('tripledes', '', 'ecb', '');
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($td), MCRYPT_RAND);
mcrypt_generic_init($td, $key, $iv);
$id = mdecrypt_generic($td, $_COOKIE['value']);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);