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Full Discussion: Bash - array loop performance
Top Forums Shell Programming and Scripting Bash - array loop performance Post 302919565 by math4 on Thursday 2nd of October 2014 06:14:16 AM
Old 10-02-2014
I have rewrite the function in perl: wow, very fast!
I like perl seem easy to understand.
If someone is interested...

Code:
sub decrypt {
    my ($f, $key) = @_;
    my $s;
    {
      local *FH;
      open FH, "$f" or die $!;
      -f FH and sysread FH, $s, -s FH;
    }
    my $n=length($s);
    my $k1=11+($key % 233); my $k2= 7+($key % 239);
    my $k3= 5+($key % 241); my $k4= 3+($key % 251);
    my @sn = unpack("C*", $s);   
  # debug: print "@sn\n";
    my $i=0;
    for ($i=0; $i<($n-2); $i++) { $sn[$i]=(($sn[$i] ^ $sn[$i+2] ^ ($k4 * $sn[$i+1])) % 256); }
    for ($i=($n-1); $i>1; $i--) { $sn[$i]=(($sn[$i] ^ $sn[$i-2] ^ ($k3 * $sn[$i-1])) % 256); }
    for ($i=0; $i<($n-1); $i++) { $sn[$i]=(($sn[$i] ^ $sn[$i+1] ^ ($k2 * $sn[$i+1])) % 256); }
    for ($i=($n-1); $i>0; $i--) { $sn[$i]=(($sn[$i] ^ $sn[$i-1] ^ ($k1 * $sn[$i-1])) % 256); }
    $s=""; for ($i=0; $i<$n; $i++) { $s.=chr( $sn[$i] ); }  
}

 

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LEARN ABOUT DEBIAN

gnunet-rsa

GNUNET-RSA(1)						      General Commands Manual						     GNUNET-RSA(1)

NAME

       gnunet-rsa - manipulate GNUnet RSA key files

SYNOPSIS

       gnunet-rsa [options]FILENAME

DESCRIPTION

       gnunet-rsa  can	be used to create an RSA private key and to print the corresponding public key.  You must specify a filename containing an
       RSA private key in GNUnet format as an argument.  If the file does not exist, gnunet-rsa will create a key.  This may then  take  a  while.
       If the option -p is given, the corresponding public key will be printed to the console.

OPTIONS

       -p, --print-public-key
	      Print the corresponding public key to stdout.

       -P, --print-peer-identity
	      Print the corresponding peer identity (hash of the public key) to stdout.  This hash is used for the name of peers.

       -s, --print-short-identity
	      Print the corresponding short hash (256-bit hash of the public key) to stdout.  This hash is used for names in the zkey zone.

       -c FILENAME,  --config=FILENAME
	      Use the configuration file FILENAME.

       -h, --help
	      Print short help on options.

       -L LOGLEVEL, --loglevel=LOGLEVEL
	      Use LOGLEVEL for logging.  Valid values are DEBUG, INFO, WARNING and ERROR.

       -v, --version
	      Print GNUnet version number.

BUGS

       Report bugs by using Mantis <https://gnunet.org/bugs/> or by sending electronic mail to <gnunet-developers@gnu.org>

GNUnet								   Mar 15, 2012 						     GNUNET-RSA(1)
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