[HaBo]

#!/usr/bin/perl -w
use strict;

open FILE, "> file.txt";
binmode FILE;
print FILE chr(65); # schreibe 'A'
print FILE chr(66); # schreibe 'B'
print FILE chr(67); # schreibe 'C'
print FILE "\n";     #  Zeilenumbruch 
close FILE;
exit 0;

cat file.txt 
ABC

#!/usr/bin/perl -w
use strict;

my $crypt_factor=5;

#$1: input text-file
#$2: encrypted outputfile

  sub encrypt() {
    my ($file, $outfile) = @_;
    my $buffer_out;
    my $symbol;
    open (FIN, "<", $file) || die "cannot open file: $file\n";
    my @buffer=<FIN>;
    close(FIN);
    open (FOUT, ">", "$outfile") || die "cannot open output file: $outfile\n";
    binmode(FOUT);
    map {
      my $pointer=\$_;                           # Zeiger auf aktuelle Zeile
      my $len=length($$pointer);                 # Zeilenlaenge ermitteln
      my $xor_str=($crypt_factor) x $len;        # xor-Pattern erzeugen, gleiche Laenge wie akt. Zeile
      my $out_str=$$pointer ^ $xor_str;          # xor Pattern ueber String legen
      my @out_vector=unpack("C$len", $out_str);  # xor-verschluesselte Zeichen als Single-Bytes in Vektor speichern
      for (@out_vector) {
        print FOUT $_ || die ("error while writing to output file: $outfile\n");
      }
    } @buffer;
    close(FOUT);
    return 0;
  }

my $f=shift @ARGV;
&encrypt("$f", "$f.crypt");
exit 0;

./encrypt.pl test.txt

cat test.txt
zeile 1
zeile 2
zeile 3
ende

cat test.txt.crypt 
1499222095105723220814992220951057428816149922209510573632801347509072