NAME

Crypt::Rot47 - Encryption and decryption of ASCII text using the ROT47 substitution cipher.

SYNOPSIS

  # Object-oriented interface
  use Crypt::Rot47; 

  my $cipher = new Crypt::Rot47();
  my $ciphertext = $cipher->encrypt('Shhh... this is a secret message');

  print "$ciphertext\n";     # Prints "$999]]] E9:D :D 2 D64C6E >6DD286"

  my $plaintext = $cipher->decrypt($ciphertext);

  print "$plaintext\n";        # Prints "Shhh... this is a secret message"

  # Simpler non-OOP interface
  use Crypt::Rot47 qw(rot47);

  my $ciphertext = rot47('Shhh... this is a secret message');
  my $plaintext  = rot47($ciphertext);

DESCRIPTION

This module applies the ROT47 substitution cipher to ASCII text, thereby scrambling it and making it difficult for others to read. Applying the same ROT47 substitution cipher on the scrambled text will then restore the original text.

The ROT47 substitution cipher is a very simple form of encryption that works simply by rotating the ASCII characters from '!" to '~' by 47 positions (hence its name). Therefore, spaces in the plain text remain unchanged, but other characters are replaced with their rotated equivalents.

For example, a 'B' (ASCII 66) becomes a 'q' (ASCII 113) because 66 + 47 = 113. When the sum exceeds ASCII 126 ('~'), it simply wraps around starting at ASCII 33 ('!').

Because there are 94 characters between '!' and '~' in the ASCII table, rotating them twice by 47 places has no net effect. Therefore, encryption and decryption are identical operations with ROT47.

For more information about ROT47, see http://en.wikipedia.org/wiki/ROT13.

CONSTRUCTOR

new

  use Crypt::Rot47;
  my $cipher = new Crypt::Rot47();

Returns a newly created Crypt::Rot47 object.

METHODS

encrypt ( $plain_text )

  my $cipherText = $cipher->encrypt('Hello, world!');

Returns the ciphertext of the provided plaintext.

decrypt ( $cipher_text )

  my $plainText  = $cipher->decrypt($cipherText);

Returns the plaintext of the provided ciphertext. Note that because encrypting and decrypting using ROT47 are exactly the same operation, you could technically just call encrypt() to decrypt the ciphertext, but I provided both methods to be consistent with the API of other Crypt:: modules.

EXPORTABLE SUBROUTINES

rot47 ( $plain_text | $cipher_text )

  use Crypt::Rot47 qw(rot47);

  my $cipherText = rot47('Hello, world!'); 
  my $plainText = rot47($cipherText);

Encrypts or decrypts the provided text. For ROT47, encryption and decryption are the same operation, so calling rot47() on text twice has no effect.

SEE ALSO

Crypt::Rot13, Crypt::Blowfish, Crypt::IDEA

AUTHOR

Zachary Blair, <zblair@cpan.org>

COPYRIGHT AND LICENSE

Copyright (C) 2012 by Zachary Blair

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.

cpanm Crypt::Rot47

perl -MCPAN -e shell
install Crypt::Rot47