This program brute force decodes an RC4 encrypted message. On my Core2Quad 2.4ghz, it processed about 2000 iterations a second. A C programmer has his own similar brute force code that processes about 300,000 iterations a second. He advises that this is a clear example of compiled code over interpreted code. Since I learned most my perl from perlmonks, web sites and books, this is the most optimized code I could manage. It could be that the RC4 algorithm is much slower than the C lib or maybe there is some glaring element of my code that can be optimized. I would appreciate any suggestions and advice and would be really happy to prove my code is the problem and not perl. Thanks! 
#!/perl/bin/perl
use Crypt::RC4;

$data1="C5C444220AD6FB08972792318300CC703814513EE013AF97B94FF9ACF23F9C
+8F0E748C04B2E18BB5A1B491BB73E23EC9A4233B9BCDE4854FD03DCBAC4B3E9EA00F5
+BF7A3A119B0FF2E66C9DD96E7F4F0972959082601AA5DD202DFB0
5039CA4FDC280517E244353690C0DE1A";

$foo1=pack('H*',"$data1");

$dt=`/cygwin/bin/date`;
chomp $dt;
print "$dt Start \n";

$key=A;
while ( 1 ){
   $SKIP=0;
   $ct++;
   $ucrypt=RC4($key,$foo1);
   $clen = length($ucrypt);
   @uchar = split(//,$ucrypt);
   for($i=0; $i<($clen); $i++) {
      $val = ord($uchar[$i]);
      if($val>127) {
      $SKIP=1;
        last;
      }
   }
   
   if ( $ct == 10000 ){
      $dt=`/cygwin/bin/date`;
      chomp $dt;
      print "$dt count $ct key: $key \n";
      $ct=0;
   }
   if ($SKIP == 0 ){
       print "matched using key:$key \n";
       print "$ucrypt \n";
   }
$key++;

}

exit;

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In reply to RC4 cipher performance by jaiello

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