Crypt::CFB - Encrypt Data in Cipher Feedback Mode
use Crypt::CFB; my $cipher = new Crypt::CFB $key, 'Crypt::Rijndael'; ## Or: my $iv = ''; map { $iv .= chr(rand(256)) } (0..16); my $cipher = new Crypt::CFB $key, 'Crypt::Rijndael', $iv; my $ciphertext = $cipher->encrypt($plaintext); my $plaintext = $cipher->decrypt($ciphertext); my $cipher2 = new Crypt::CFB $key, 'Digest::MD5'; $ciphertext = $cipher->encrypt($plaintext); $plaintext = $cipher->decrypt($ciphertext);
Generic CFB implementation in pure Perl. The Cipher Feedback Mode module constructs a stream cipher from a block cipher or cryptographic hash funtion and returns it as an object. Any block cipher in the Crypt:: class can be used, as long as it supports the blocksize and keysize methods. Any hash function in the Digest:: class can be used, as long as it supports the add method.
Crypt::
blocksize
keysize
Digest::
add
$cipher = new Crypt::CFB $key, $algorithm, $optional_iv
Constructs a CFB object. If $algorithm is a block cipher, then $key should be of the correct size for that cipher. In most cases you can inquire the block cipher module by invoking the keysize method. If $algorithm is a hash function (Digest::), then $key can be of any size. The optional IV can be used to further seed the crypto algorithm. If no IV is given, a string of zeroes is used.
$algorithm
$key
$ciphertext = $cipher->encrypt $plaintext
Encrypts $plaintext. The input is XORed with the keystream generated from the internal state of the CFB object and that state is updated with the output. $plaintext can be of any length.
$plaintext
$cipher->reset
Resets the internal state. Remember to do that before decrypting, if you use the same object.
$plaintext = $cipher->decrypt $ciphertext
Decrypts $ciphertext.
$ciphertext
This is awfully slow. Some classes in Digest:: do not provide the add method, so they will fail. The implementation is a little baroque.
Matthias Bauer <matthiasb@acm.org>
Added the use of an IV.
Kees Jan Hermans <kees@phoezo.com>
To install Crypt::CFB, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Crypt::CFB
CPAN shell
perl -MCPAN -e shell install Crypt::CFB
For more information on module installation, please visit the detailed CPAN module installation guide.