note 93440 added to function.hash-hmac

Sometimes a hosting provider doesn't provide access to the Hash extension. Here is a clone of the hash_hmac function you can use in the event you need an HMAC generator and Hash is not available. It's only usable with MD5 and SHA1 encryption algorithms, but its output is identical to the official hash_hmac function (so far at least). <?php function custom_hmac($algo, $data, $key, $raw_output = false) { $algo = strtolower($algo); $pack = 'H'.strlen($algo('test')); $size = 64; $opad = str_repeat(chr(0x5C), $size); $ipad = str_repeat(chr(0x36), $size); if (strlen($key) > $size) { $key = str_pad(pack($pack, $algo($key)), $size, chr(0x00)); } else { $key = str_pad($key, $size, chr(0x00)); } for ($i = 0; $i < strlen($key) - 1; $i++) { $opad[$i] = $opad[$i] ^ $key[$i]; $ipad[$i] = $ipad[$i] ^ $key[$i]; } $output = $algo($opad.pack($pack, $algo($ipad.$data))); return ($raw_output) ? pack($pack, $output) : $output; } ?> Example Use: <?php custom_hmac('sha1', 'Hello, world!', 'secret', true); ?> ---- Server IP: 208.69.120.35 Probable Submitter: 76.115.133.105 ---- Manual Page -- http://www.php.net/manual/en/function.hash-hmac.php Edit -- https://master.php.net/note/edit/93440 Del: integrated -- https://master.php.net/note/delete/93440/integrated Del: useless -- https://master.php.net/note/delete/93440/useless Del: bad code -- https://master.php.net/note/delete/93440/bad+code Del: spam -- https://master.php.net/note/delete/93440/spam Del: non-english -- https://master.php.net/note/delete/93440/non-english Del: in docs -- https://master.php.net/note/delete/93440/in+docs Del: other reasons-- https://master.php.net/note/delete/93440 Reject -- https://master.php.net/note/reject/93440 Search -- https://master.php.net/manage/user-notes.php