[Bcrypt-users] bcrypt file format?

[Dossy S. <do...@pa...>]

Hi,

I'm trying to use PHP and Mcrypt to decrypt a file that has been
encrypted using bcrypt 1.1.

I've modified bcrypt to dump the 448-bit key it has generated and am
using this snippet to try and decrypt the payload, which is simply the
LICENSE file from bcrypt, encrypted without compression using the same
"eggheads" key.

<?php
/*
 * Bcrypt uses a 56-byte (448-bit) key.
 */

$key = pack("H*",
"1E8CD6418B373C741C415CF5F0E482476C66B1FDC3E37EEEFE7C8C704D9139A9A4CA24B53858A261C59F4F94383F9046D38E16A9E21BB242");

// $key = pack("H*",
"85071DE15C3282516DD6B725BD7A1511B6639928BE1D4F99E54DF3FC4C811E48038FDE1669CAA017516FA502785B8D020616F26A61CCB39D");

        $td = mcrypt_module_open(MCRYPT_BLOWFISH, '', 'ecb', '');
$iv = '00000000';

mcrypt_generic_init($td, $key, $iv);
$plaintext = mdecrypt_generic($td, file_get_contents("uncompressed.bfe"));
mcrypt_generic_deinit($td);
mcrypt_module_close($td);

var_dump($plaintext);
?>

Yet, this doesn't yield the plaintext.  What's the trick?  What is
bcrypt actually doing?

-- 
Dossy Shiobara              | do...@pa... | http://dossy.org/
Panoptic Computer Network   | http://panoptic.com/
  "He realized the fastest way to change is to laugh at your own
    folly -- then you can let go and quickly move on." (p. 70)