rsa.signature.php

<?php
error_reporting(E_ALL);

/*
Written by Antimatter15. Released to Public Domain.
Changes:
  December 3 - Created
  December 5 - Fixed bug (undefined bmadd), Switched to raw SHA-1 (allow < 512 bit keys), Fixed Adding, Undefined variable, Uninitialized String 
*/

/*
Parameters:
  $m - Message
  $e - Encryption Exponent
  $n - Modulo

Returns:
  string signature
*/
function sign($m, $e, $n) {
  $m=sha1($m, true);
  $c="";
  for($j=0; $j<20; $j++){ 
    $c = bcadd($c, bcmul(ord($m[$j]), bcpow('256',$j)));
  }
  return bcpowmod($c, $e, $n); 
}


/*
Parameters:
  $m - Message
  $s - Signature
  $d - Decryption Exponent
  $n - Modulo

Returns:
  Boolean passes verification or not
*/
function verify($m, $s, $d, $n) { 
  $t = ''; 
  $c = bcpowmod($s, $d, $n); 
  while(bccomp($c, '0') != 0){ 
    $t .= chr(bcmod($c, '256')); 
    $c = bcdiv($c, '256', 0); 
  } 
   return $t==sha1($m, true);
}
/*
$e = "3514154152523482244510025679905027432832717686149733933270841589963848086479";
$d = "1345113334183320009999299256137330751442566269958512189873637535318199721119";
$n = "4876682701309516951234725500059641167033512755752338611478313046145089995111";

$msg = "Woot I am a poop";
$sgn = sign($msg, $e, $n);
echo "Signature: ", $sgn,"\n";
echo verify($msg, $sgn,  $d, $n)?"WOOT":"POOP","\n";
*/

Is "$n" calculate hash of message?