B58013A7FF

##</code><code>##

while (<DATA>) {
    chomp;
    my $out = '';
    while ( /([0-9a-f]{2})/gi ) {
       $out .= ( uc($1) eq 'A7' ) ? "00" : $1;
    }
    print "$out\n";
}

__DATA__
b58013A7FF


##</code><code>##

binmode STDIN;
binmode STDOUT;
$/ = \8192;  # set "input record separator" to 8KB per read

while (<>) {
    tr/\xa7/\x00/;
    print;
}

##</code><code>##

script.pl < input.file > output.file