I am arguing for one way encryption rather than hashing. Hashing functions are ridiculously fast. even with a hundred rounds you can try 10000 passwords per second as shown by the following sample php I wrote for you.

<?php

function gcrypt($ename,$emode,$text,$key,$ivtext,$crypt)

{

$encrypted_data="";

$td = mcrypt_module_open($ename, '', $emode, '');

if( $td==false ){echo "could not open crypt module ".$ename;return "";}

$ivlen = mcrypt_enc_get_iv_size($td);

$keylen = mcrypt_enc_get_key_size($td);

$iv = substr( $ivtext, 0, $ivlen );

$key = substr($key, 0, $keylen);

// echo "key=$key.$keylen.$ivlen.$iv.";

$s = mcrypt_generic_init($td, $key, $iv);

if( ($s < 0) || ($s === false))dieres( "hasher mcrypt_generic_init failed" );

if($crypt){

$edata = mcrypt_generic($td, $text);

}else {

$edata = mdecrypt_generic($td, $text);

}

mcrypt_generic_deinit($td);

mcrypt_module_close($td);

return $edata;

}

function hasher($ename,$emode,$text,$ivtext)

{

$key = strrev($text)."kjlsdflsdakjflsdkafjjsldkjflkj";

return gcrypt($ename,$emode,$text,$key,$ivtext,1);

}

function pass2key( $algo, $text, $ivtext )

{

$ivtext = mb_strtolower( $ivtext, 'UTF-8' );

$ivtext .= "lksadfkjsadfsadfhsdaklfsadlkfj";

$text = substr( $text."lsdkfjsdalkfjsdalkfjsldakfjlsdakjfjlksdafjsdkaj", 0, 64 );

for( $i=0;$i<1000;$i++ ){

$text = hasher( $algo, 'cbc', $text, $ivtext );

}

return $text;

}

function timealgo( $algo )

{

$start = microtime( true );

pass2key( $algo, "This is a test password", "username" );

echo "algo- $algo:".(microtime(true)-$start)."";

}

function pass2key2( $hash, $text )

{

$text = substr( $text."lsdkfjsdalkfjsdalkfjsldakfjlsdakjfjlksdafjsdkaj", 0, 64 );

for( $i=0;$i<1000;$i++ ){

$text = hash( $hash, $text, true );

}

return $text;

}

function timehash( $algo )

{

$start = microtime( true );

pass2key2( $algo, "This is a test password" );

echo "hash- $algo:".(microtime(true)-$start)."";

}

timealgo( 'blowfish' );

timealgo( 'twofish' );

timehash( 'sha512' );

timehash( 'sha256' );

?>

Sample times on one of my dedis:

algo- blowfish:0.75880813598633

algo- twofish:0.43758201599121

hash- sha512:0.0042619705200195

hash- sha256:0.00357985496521

As you can see blowfish or twofish or any other encryption algo is 100 times slower than any hashing algorithms for a matching number of rounds. It is ridiculous to use hashing algorithms to store passwords.

If you encrypt a password with itself with a suitable salt and the user name as iv. Then there is no need to store the encryption key for some one to hack it. The original password cant be recovered from the hash even though it is a symmetric encryption. As you can see the sample program above uses the password to encrypt itself. there is no way to go back to the password from the resulting key is there?