NAME¶
Crypt::CipherSaber - Perl module implementing CipherSaber encryption.
SYNOPSIS¶
use Crypt::CipherSaber;
my $cs = Crypt::CipherSaber->new('my pathetic secret key');
my $coded = $cs->encrypt('Here is a secret message for you');
my $decoded = $cs->decrypt($coded);
# encrypt from and to a file
open(INFILE, 'secretletter.txt') or die "Can't open infile: $!";
open(OUTFILE, '>secretletter.cs1') or die "Can't open outfile: $!";
binmode(INFILE);
binmode(OUTFILE);
$cs->fh_crypt(\*INFILE, \*OUTFILE, 1);
# decrypt from and to a file
open(INFILE, 'secretletter.cs1') or die "Can't open infile: $!";
open(OUTFILE, '>secretletter.txt') or die "Can't open outfile: $!";
binmode(INFILE);
binmode(OUTFILE);
$cs->fh_crypt(\*INFILE, \*OUTFILE);
DESCRIPTION¶
The Crypt::CipherSaber module implements CipherSaber encryption, described at
http://ciphersaber.gurus.com. It is simple, fairly speedy, and relatively
secure algorithm based on RC4.
Encryption and decryption are done based on a secret key, which must be shared
with all intended recipients of a message.
METHODS¶
- new($key, $N)
- Initialize a new Crypt::CipherSaber object. $key, the key used to encrypt
or to decrypt messages is required. $N is optional. If provided and
greater than one, it will implement CipherSaber-2 encryption (slightly
slower but more secure). If not specified, or equal to 1, the module
defaults to CipherSaber-1 encryption. $N must be a positive integer
greater than one.
- encrypt($message)
- Encrypt a message. This uses the key stored in the current
Crypt::CipherSaber object. It will generate a 10-byte random IV
(Initialization Vector) automatically, as defined in the RC4
specification. This returns a string containing the encrypted message.
Note that the encrypted message may contain unprintable characters, as it
uses the extended ASCII character set (valid numbers 0 through 255).
- decrypt($message)
- Decrypt a message. For the curious, the first ten bytes of an encrypted
message are the IV, so this must strip it off first. This returns a string
containing the decrypted message.
The decrypted message may also contain unprintable characters, as the
CipherSaber encryption scheme can handle binary files with fair ease. If
this is important to you, be sure to treat the results correctly.
- crypt($iv, $message)
- If you wish to generate the IV with a more cryptographically secure random
string (at least compared to Perl's builtin rand() function), you
may do so separately, passing it to this method directly. The IV must be a
ten-byte string consisting of characters from the extended ASCII set.
This is generally only useful for encryption, although you may extract the
first ten characters of an encrypted message and pass them in yourself.
You might as well call decrypt(), though. The
more random the IV, the stronger the encryption tends to be. On some
operating systems, you can read from /dev/random. Other approaches are the
Math::TrulyRandom module, or compressing a file, removing the headers, and
compressing it again.
- fh_crypt(\*INPUT, \*OUTPUT, ($iv))
- For the sake of efficiency, Crypt::CipherSaber can now operate on
filehandles. It's not super brilliant, but it's relatively fast and sane.
Pass in a reference to the input file handle and the output filehandle. If
your platform needs to use "binmode()", this is your
responsibility. It is also your responsibility to close the files.
You may also pass in an optional third parameter, an IV. There are three
possibilities here. If you pass no IV, "fh_crypt()" will pull
the first ten bytes from *INPUT and use that as an IV. This corresponds to
decryption. If you pass in an IV of your own (generally ten digits, but
more than one digits as the code is now), it will use your own IV when
encrypting the file. If you pass in the value '1', it will generate a new,
random IV for you. This corresponds to an encryption.
COPYRIGHT AND LICENSE¶
Copyright (C) 2000 - 2001 chromatic
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.
AUTHOR¶
chromatic <chromatic@wgz.org>
thanks to jlp for testing, moral support, and never fearing the icky details and
to the fine folks at
http://perlmonks.org
Additional thanks to Olivier Salaun and the Sympa project (
http://www.sympa.org)
for testing.
SEE ALSO¶
the CipherSaber home page at
http://ciphersaber.gurus.com
perl(1),
rand().