Crypt::OOEnigma::Reflector - The Reflector object for use in Crypt::OOEnigma

Crypt-OOEnigma documentation Contained in the Crypt-OOEnigma distribution.

Index

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NAME

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Crypt::OOEnigma::Reflector - The Reflector object for use in Crypt::OOEnigma

SYNOPSIS

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  my $reflector = Crypt::OOEnigma::Reflector->new();

  # OR

  my $subHash ={ # A self-inverse cipher with no short-circuits
                 A => "Z",
                 B => "G",
                 # etc
               };
  my $reflector = Crypt::OOEnigma::Reflector->new(cipher  => $subHash);

  # for internal use by Enigma machines
  my $reflected_letter = $reflector->reflect($some_letter);

DESCRIPTION

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This is the Reflector for use in Crypt::OOEnigmas. Use it when you want to create your own Enigmas with specific properties.

NOTES

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None

BUGS and CAVEATS

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Enigma is weak!

Cryptographers talk of the strength of a cryptographic algorithm in term of whether it is computationally feasible to break it. It is, of course, computationally feasible to break an Enigma cipher so don't use it for anything serious!

HISTORY

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This package was created in spring 2002 as an exercise in OO Perl and preparing modules properly for CPAN. More importantly, the Enigma is interesting.

CPAN already has a Crypt::Enigma which is not object oriented and implements only one Enigma (whereas you can create any Enigma-like machine with these objects). Hence the package name Crypt::OOEnigma

SEE ALSO

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The Pleasures of Counting, T W Korner, CUP 1996. A great book for anyone with the slightest interest in mathematics: ISBN 0 521 56087 X hardback ISBN 0 521 56823 4 paperback

The Enigmas: Crypt::OOEnigma::Military Crypt::OOEnigma::Commercial

The components: Crypt::OOEnigma::Rotor Crypt::OOEnigma::Reflector Crypt::OOEnigma::Plugboard

AUTHOR

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S J Baker, Ambriel Consulting, http://ambrielconsulting.com

COPYRIGHT

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This package is licenced under the same terms as Perl itself.

Crypt-OOEnigma documentation Contained in the Crypt-OOEnigma distribution. 
#!/usr/bin/perl -w
#
# Reflector.pm
#
# Copyright (c) 2002 Ambriel Consulting
# sjb Sun Mar 17 20:43:56 GMT 2002
#

package Crypt::OOEnigma::Reflector ;
$VERSION="0.3";

use Storable ;
use Carp ;

# The reflector's substitution must be self-inverse
my $subst = {
  A => "Z", B => "Y", C => "X", D => "W", E => "V",
  F => "U", G => "T", H => "S", I => "R", J => "Q",
  K => "P", L => "O", M => "N", N => "M", O => "L",
  P => "K", Q => "J", R => "I", S => "H", T => "G",
  U => "F", V => "E", W => "D", X => "C", Y => "B",
  Z => "A"
};

my %fields = (
  cipher   => $subst,
);

# use Autoloading for accessors
use subs qw(cipher);

sub new {
  my $invocant = shift ;
  my $class = ref($invocant) || $invocant ;
  my $self = { %fields, @_ } ; 
  bless $self, $class ;

  # TODO: check the cipher is in fact self-inverse

  return $self ;
}

sub reflect {
  my $self = shift;
  my $source = shift;
  return $self->cipher()->{$source};
}

sub AUTOLOAD {
  my $self = shift;
  # only access instance methods not class methods
  croak "$self is not an object" unless(ref($self));
  my $name = our $AUTOLOAD;
  return if($name =~ /::DESTROY/ );
  $name =~ s/.*://;   # strip fully-qualified portion
  unless (exists $self->{$name} ) {
    croak "Can't access `$name' field in object of class $self";
  } 
  if (@_) {
    return $self->{$name} = shift;
  } else {
    return $self->{$name};
  } 
}

1;