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OS/pintos-env/pintos/tests/arc4.pm

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Perl
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use strict;
use warnings;
sub arc4_init {
my ($key) = @_;
my (@s) = 0...255;
my ($j) = 0;
for my $i (0...255) {
$j = ($j + $s[$i] + ord (substr ($key, $i % length ($key), 1))) & 0xff;
@s[$i, $j] = @s[$j, $i];
}
return (0, 0, @s);
}
sub arc4_crypt {
my ($arc4, $buf) = @_;
my ($i, $j, @s) = @$arc4;
my ($out) = "";
for my $c (split (//, $buf)) {
$i = ($i + 1) & 0xff;
$j = ($j + $s[$i]) & 0xff;
@s[$i, $j] = @s[$j, $i];
$out .= chr (ord ($c) ^ $s[($s[$i] + $s[$j]) & 0xff]);
}
@$arc4 = ($i, $j, @s);
return $out;
}
1;