?php
function hmacsha1($key,$data) {
 $blocksize=64;
 $hashfunc='sha1';
 if (strlen($key)>$blocksize)
  $key=pack('H*', $hashfunc($key));
 $key=str_pad($key,$blocksize,chr(0x00));
 $ipad=str_repeat(chr(0x36),$blocksize);
 $opad=str_repeat(chr(0x5c),$blocksize);
 $hmac = pack(
    'H*',$hashfunc(
     ($key^$opad).pack(
      'H*',$hashfunc(
       ($key^$ipad).$data
      )
     )
    )
   );
 return $hmac;
}
?>