Getting CakePHP to use phpBB3 users and passwords

I'm tinkering with a small CakePHP app and I want to add users but allow them to authenticate against my phpBB3 forum credentials.  I found a few attempts and suggestions that didn't work for me and the bridge available in the Bakery isn't wwhat I wanted either.

After banging my head against a bit of stupid, I found it to be easy by just copying over some phpBB3 functions and following the CakePHP manual pages on changing Auth's hash function. 

User model (app/models/user.php)

class User extends AppModel {

	var $name = 'Users';

	var $useDbConfig  = 'phpbbdb'; // for users
	var $tablePrefix  = 'phpbb_';
	var $primaryKey   = 'user_id';
	var $displayField = 'username';

	// from phpbb code
	function _phpbb_check_hash($password, $hash)
	{
		$itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
		if (strlen($hash) == 34)
		{
			return ($this->_hash_crypt_private($password, $hash, $itoa64) === $hash) ? true : false;
		}

		return (md5($password) === $hash) ? true : false;
	}

	// from phpbb code
	function _phpbb_hash($password)
	{
		$itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';

		// customized here
		$random_state = $this->unique_id();
		$random = '';
		$count = 6;

		if (($fh = @fopen('/dev/urandom', 'rb')))
		{
			$random = fread($fh, $count);
			fclose($fh);
		}

		if (strlen($random) < $count)
		{
			$random = '';

			for ($i = 0; $i < $count; $i += 16)
			{
				$random_state = md5($this->unique_id() . $random_state);
				$random .= pack('H*', md5($random_state));
			}
			$random = substr($random, 0, $count);
		}

		$hash = $this->_hash_crypt_private($password, $this->_hash_gensalt_private($random, $itoa64), $itoa64);

		if (strlen($hash) == 34)
		{
			return $hash;
		}

		return md5($password);
	}

	// from phpbb code
	function _hash_crypt_private($password, $setting, &$itoa64)
	{
		$output = '*';

		// Check for correct hash
		if (substr($setting, 0, 3) != '$H$')
		{
			return $output;
		}

		$count_log2 = strpos($itoa64, $setting[3]);

		if ($count_log2 < 7 || $count_log2 > 30)
		{
			return $output;
		}

		$count = 1 << $count_log2;
		$salt = substr($setting, 4, 8);

		if (strlen($salt) != 8)
		{
			return $output;
		}

		/**
		* We're kind of forced to use MD5 here since it's the only
		* cryptographic primitive available in all versions of PHP
		* currently in use.  To implement our own low-level crypto
		* in PHP would result in much worse performance and
		* consequently in lower iteration counts and hashes that are
		* quicker to crack (by non-PHP code).
		*/
		if (PHP_VERSION >= 5)
		{
			$hash = md5($salt . $password, true);
			do
			{
				$hash = md5($hash . $password, true);
			}
			while (--$count);
		}
		else
		{
			$hash = pack('H*', md5($salt . $password));
			do
			{
				$hash = pack('H*', md5($hash . $password));
			}
			while (--$count);
		}

		$output = substr($setting, 0, 12);
		$output .= $this->_hash_encode64($hash, 16, $itoa64);

		return $output;
	}

	// from phpbb code
	function _hash_gensalt_private($input, &$itoa64, $iteration_count_log2 = 6)
	{
		if ($iteration_count_log2 < 4 || $iteration_count_log2 > 31)
		{
			$iteration_count_log2 = 8;
		}

		$output = '$H$';
		$output .= $itoa64[min($iteration_count_log2 + ((PHP_VERSION >= 5) ? 5 : 3), 30)];
		$output .= $this->_hash_encode64($input, 6, $itoa64);

		return $output;
	}

	// from phpbb code
	function _hash_encode64($input, $count, &$itoa64)
	{
		$output = '';
		$i = 0;

		do
		{
			$value = ord($input[$i++]);
			$output .= $itoa64[$value & 0x3f];

			if ($i < $count)
			{
				$value |= ord($input[$i]) << 8;
			}

			$output .= $itoa64[($value >> 6) & 0x3f];

			if ($i++ >= $count)
			{
				break;
			}

			if ($i < $count)
			{
				$value |= ord($input[$i]) << 16;
			}

			$output .= $itoa64[($value >> 12) & 0x3f];

			if ($i++ >= $count)
			{
				break;
			}

			$output .= $itoa64[($value >> 18) & 0x3f];
		}
		while ($i < $count);

		return $output;
	}

    private function unique_id($extra = 'c') {
        static $dss_seeded = false;
        global $config;
        
        $val = $config ['rand_seed'] . microtime ();
        $val = md5 ( $val );
        $config ['rand_seed'] = md5 ( $config ['rand_seed'] . $val . $extra );
        
        $dss_seeded = true;
        return substr ( $val, 4, 16 );
    } 

	function hashPasswords($data)
	{
		if (isset($data['User']['user_password']))
		{
			$phpbb_pw = $this->field('user_password', array('username' => $data['User']['username']));
			if ($this->_phpbb_check_hash($data['User']['user_password'], $phpbb_pw))
			{
				$data['User']['user_password'] = $phpbb_pw;
			}

			return $data;
		}
		return $data;
	}

}

User controller (app/controllers/user_controller.php)

class UsersController extends AppController {

    var $name = 'Users';
    var $helpers = array('Html', 'Form');

    function beforeFilter()
    {
        $this->Auth->authenticate = ClassRegistry::init('User');

        $this->Auth->fields = array(
            'username' => 'username',
            'password' => 'user_password'
        );

        parent::beforeFilter();
    }

    function login()
    {
    }

    function logout()
    {
        $this->redirect($this->Auth->logout());
    }
}

Make sure to set up the login view and follow the other general instructions for auth in the CakePHP manual.