note 96715 added to function.hash

A while back when helping out on a project relying on message digests for verifying the integrity of staggering amounts of data, I bumped into some interesting differences in how the various ciphers perform on different architectures. For the intended deployment platform, I was able to increase both security, performance and message quality, all at the same time. Don't assume that a cipher will always be computationally more demanding just because it's more complex, or because its message size is larger than that of another cipher: <?php $rep = 20; $num = 250; $size = 32 * 1024; $ciphers = array( 'sha256', 'sha512', 'whirlpool' ); // create 250 random messages, each 32kb in size for( $i = 0; $i < $num; $i++ ) { $c = 0; $tmp = null; while( $c++ < $size / 16 ) $tmp .= md5( mt_rand(), true ); @$data[] = $tmp; } // digest 5000 times foreach( $ciphers as $cipher ) { $r = $rep; $then = microtime( true ); while( $r-- ) { for( $i = 0; $i < $num; $i++ ) $tmp = hash( $cipher, $data[$i], true ); } echo "$cipher: " . ( microtime(true) - $then ) . PHP_EOL; } ?> On an AMD Athlon 64, running in 1ghz: sha256: 7.2770738601685 <-- sha512: 17.481907844543 <-- whirlpool: 30.047662973404 After moving the platform to a 45nm Intel Core 2, clocked down to also run in 1ghz (with no dual core action going on); same OS setup; same PHP setup; no recompiling: sha256: 4.328763961792 <-- sha512: 2.7524480819702 <-- ! whirlpool: 8.7933950424194 ---- Server IP: 194.236.124.41 Probable Submitter: 83.227.160.33 ---- Manual Page -- http://www.php.net/manual/en/function.hash.php Edit -- https://master.php.net/note/edit/96715 Del: integrated -- https://master.php.net/note/delete/96715/integrated Del: useless -- https://master.php.net/note/delete/96715/useless Del: bad code -- https://master.php.net/note/delete/96715/bad+code Del: spam -- https://master.php.net/note/delete/96715/spam Del: non-english -- https://master.php.net/note/delete/96715/non-english Del: in docs -- https://master.php.net/note/delete/96715/in+docs Del: other reasons-- https://master.php.net/note/delete/96715 Reject -- https://master.php.net/note/reject/96715 Search -- https://master.php.net/manage/user-notes.php