Figuring out the exact key created by PHP's mcrypt

Question

A PHP application I\'m maintaining uses Rijndael_256 with EBC_MODE encryption with mcrypt. Fun has it that the key isn\'t 256 bits long, but only 160. According to the mcryp

Answer 1

'\0' means NULL, the hex value of it is 00 ! So i tested 3 codes, and they returned all the same :)

1. Let mcrypt_encrypt do the '\0' padding
2. Added with PHP NULL values
3. Added with PHP converted 0 hex values

Code:

function encryptThis($text,$key){
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    $crypttext = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB, $iv);
    return ($crypttext);
}

echo bin2hex(encryptThis("Meet me at 11 o'clock behind the monument.", "abcdefghijklmnopqrstuvwxyz"))."
";

echo bin2hex(encryptThis("Meet me at 11 o'clock behind the monument.", "abcdefghijklmnopqrstuvwxyz" . NULL . NULL . NULL . NULL . NULL . NULL))."
";

echo bin2hex(encryptThis("Meet me at 11 o'clock behind the monument.", "abcdefghijklmnopqrstuvwxyz" . hex2bin(0) . hex2bin(0) . hex2bin(0) . hex2bin(0) . hex2bin(0) . hex2bin(0)))."
";

?>