http://qs321.pair.com?node_id=9400
Category: cryptography
Author/Contact Info ergowolf
Description: creesy ROT13 or caeser encryption. This was one of the first programs I wrote on my own. It does not preserve case. 
my $text;
my $type;

# This section grabs the text from the user and converts to lower case
+.
print "Please enter the text you would like to encrypt:";
chomp($text = <STDIN>);
$text =~ tr/A-Z/a-z/;

# This section lets you pick the type of encryption you would like to 
+use.
print "Please enter c for Caesar or r for ROT13 encryption: ";
chomp($type = <STDIN>);
$type =~ tr/A-Z/a-z/;

# This section uses the encryption you chose.
if ($type eq c) {
    $text =~ tr/c-za-b/a-z/;
}
if ($type eq r) {
    $text =~ tr/n-za-m/a-z/;
}
print $text;
Replies are listed 'Best First'.
RE: Cheesy Encryption
by chromatic (Archbishop) on Apr 27, 2000 at 20:36 UTC
    Here's how to make it preserve case. The example is only for ROT-13, as you should be able to figure out the rest. First, remove the tr/A-Z/a-z/: 
    if ($type eq 'r'( {
    $text =~ tr/N-ZA-Mn-za-m/A-Za-z/;
}

    [download]
[reply]
[d/l]
      Thanks for the tip. I will try it tonight.
[reply]
RE: Cheesy Encryption
by Anonymous Monk on Jun 15, 2000 at 23:32 UTC
    Another way to do it: 
    #!/usr/bin/perl -sp
BEGIN {
        if ($h) {
                print <<"USAGE";
Usage: caesar: $0 -c filename
        rot13: $0 filename
USAGE
                exit;
        }
}
 
if( $c ) {
        tr/A-Za-z/D-ZA-Cd-za-c/;
} else {
        tr/A-Za-z/N-ZA-Mn-za-m/;
}
[reply]
      how about this? offers 3-way "encryption"... 
      #!/usr/bin/perl

use warnings;
use strict;
use Getopt::Std;

my %opt;

usage() unless (getopts('rRcCaA', \%opt));
usage() unless @ARGV;

if($opt{'r'} || $opt{'R'}) {
    while(<>) {
        tr/a-zA-Z/n-za-mN-ZA-M/;
        print;
    }
} elsif($opt{'c'}) {
    while(<>) {
        tr/a-zA-Z/d-za-cD-ZA-C/;
        print;
    }
} elsif($opt{'C'}) {
    while(<>) {
        tr/d-za-cD-ZA-C/a-zA-Z/;
        print;
    }
} elsif($opt{'a'}) {
    while(my $line = <>) {
        @_ = split//, $line;
        map { print ord($_), " "; } @_;
        print "\n";
    }
} elsif($opt{'A'}) {
    while(my $line = <>) {
        @_ = split/ /, $line;
        map { print chr($_); } @_;
        print "\n";
    }
}

sub usage {
    print << "__END__";
    -c = encrypt with Caesar encryption
    -C = decrypt from Caesar encryption
    -r = encrypt with rot13
    -R = decrypt from rot13
    -a = encrypt to numerical equivalent
    -A = decrypt back to ASCII
    example using files:
    perl $0 -r plain.txt
    perl $0 -C encrypted.txt
    example using STDIN:
    perl $0 -r <ENTER, type text>
__END__
    exit 1;
}

      [download]
[reply]
[d/l]

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