$i = 0;
for my $rec_ref(@records) {
    $new_rec = join('', $rec_ref->[0], $rec_ref->[1], $rec_ref->[2]);
    push(@new_records, $new_rec);
}
open(PASSF,">$ENV{HOME}/.perlpasswd") or die "Can't write $ENV{HOME}/.
+perlpasswd: $!\n";
for $i (0 .. $#new_rocords) {
    print PASSF $new_records[$i]^substr($newenckey,0,length($new_recor
+ds[$i]));
}
close(PASSF);
[download]

I have the same problem with this as I did with one of my earlier attempts at avoiding temporary files
The encryption is only being applied to the first element in the record not to the whole record. So what I end up with is a .perlpasswd file in this format


encrypted notencrypted notencrypted
encrypted notencrypted notencrypted
[download]

Unfortunately the third field is the password, which remains unencrypted. I've tried using map as well but always seem to end up with only the first field encrypted but not the others.
Any ideas on how I fix this would be welcome

Your use of sysread is rather buggy. It can make it impossible to decode what you encoded, because sysread can return any number of bytes for any given call. This is rather moot, since we don't need to sysread from the temporary file at all.

use strict;
use warnings;


sub getcryptkey {
   return 'ABCDEFGHIJK';
}


{
   ##### WRITER #####

   my @records = (
      [ 0, 1, 2 ],
      [ 3, 4, 5 ],
      [ 6, 7, 8 ],
   );

   my $newenckey = getcryptkey();

   local *PASSF;
   open(PASSF, ">$ENV{HOME}/.perlpasswd")
   or die("Can't write $ENV{HOME}/.perlpasswd: $!\n");

   binmode(PASSF);

   my $buf = '';

   foreach (@records) {
      # Might want to use FreezeThaw instead.
      $buf .= "$_->[0] $_->[1] $_->[2]\n"; 

      print PASSF
         substr($buf, 0, length($newenckey), '') ^ $newenckey
            while (length($buf) >= length($newenckey));
   }

   print PASSF $buf ^ substr($newenckey, 0, length($buf));

   close(PASSF);
}

{
   ##### READER #####

   my @records;

   my $newenckey = getcryptkey();

   local *PASSF;
   open(PASSF, "<$ENV{HOME}/.perlpasswd")
   or die("Can't read $ENV{HOME}/.perlpasswd: $!\n");

   binmode(PASSF);

   my $buf_e = '';
   my $buf_d = '';

   my $BLOCK_SIZE = length($newenckey); # Can be anything.

   while (sysread(PASSF, $buf_e, $BLOCK_SIZE, length($buf_e))) {

      $buf_d .= substr($buf_e, 0, length($newenckey), '') ^ $newenckey
         while (length($buf_e) >= length($newenckey));
     
      push(@records, [ $1, $2, $3 ])
         while ($buf_d =~ s/^(\S+)\s+(\S+)\s+(\S+)\n//s);
   }

   $buf_d .= $buf_e ^ substr($newenckey, 0, length($buf_e));
     
   push(@records, [ $1, $2, $3 ])
      while ($buf_d =~ s/^(\S+)\s+(\S+)\s+(\S+)\n//s);

   close(PASSF);

   require Data::Dumper;
   print(Data::Dumper::Dumper(\@records));
}

__END__
##### OUTPUT #####

$VAR1 = [
          [
            '0',
            '1',
            '2'
          ],
          [
            '3',
            '4',
            '5'
          ],
          [
            '6',
            '7',
            '8'
          ]
        ];
[download]

sysread and syswrite are properly used (except I don't check for errors), and the key is used from start to end.

print PASSF "$rec_ref->[0] $rec_ref->[1] $rec_ref->[2]" ^ 
            getcryptkey();
[download]

update: i forgot the "substr" part.

Thanks. I had actually tried something similar to this but without pushing the records into a new array first but just doing the join and then applying the encryption to the string.
needless to say it didn't work as expected