NAME

Crypt::Mode::CBC - Block cipher mode CBC [Cipher-block chaining]

SYNOPSIS

use Crypt::Mode::CBC;
my $m = Crypt::Mode::CBC->new('AES');
#(en|de)crypt at once
my $ciphertext = $m->encrypt($plaintext, $key, $iv);
my $plaintext = $m->decrypt($ciphertext, $key, $iv);
#encrypt more chunks
$m->start_encrypt($key, $iv);
my $ciphertext = $m->add('some data');
$ciphertext .= $m->add('more data');
$ciphertext .= $m->finish;
#decrypt more chunks
$m->start_decrypt($key, $iv);
my $plaintext = $m->add($some_ciphertext);
$plaintext .= $m->add($more_ciphertext);
$plaintext .= $m->finish;

DESCRIPTION

This module implements CBC cipher mode. NOTE: it works only with ciphers from CryptX (Crypt::Cipher::NNNN).

METHODS

new

my $m = Crypt::Mode::CBC->new($name);
#or
my $m = Crypt::Mode::CBC->new($name, $padding);
#or
my $m = Crypt::Mode::CBC->new($name, $padding, $cipher_rounds);
# $name ....... one of 'AES', 'Anubis', 'Blowfish', 'CAST5', 'Camellia', 'DES', 'DES_EDE',
#               'KASUMI', 'Khazad', 'MULTI2', 'Noekeon', 'RC2', 'RC5', 'RC6',
#               'SAFERP', 'SAFER_K128', 'SAFER_K64', 'SAFER_SK128', 'SAFER_SK64',
#               'SEED', 'Skipjack', 'Twofish', 'XTEA', 'IDEA', 'Serpent'
#               simply any <NAME> for which there exists Crypt::Cipher::<NAME>
# $padding .... 0 no padding (plaintext size has to be multiple of block length)
#               1 PKCS5 padding, Crypt::CBC's "standard" - DEFAULT
#               2 Crypt::CBC's "oneandzeroes"
#               3 ANSI X.923 padding
#               4 zero padding
#               5 zero padding (+a block of zeros if the output length is divisible by the blocksize)
# $cipher_rounds ... optional num of rounds for given cipher

encrypt

my $ciphertext = $m->encrypt($plaintext, $key, $iv);

decrypt

my $plaintext = $m->decrypt($ciphertext, $key, $iv);

start_encrypt

$m->start_encrypt($key, $iv);

start_decrypt

$m->start_decrypt($key, $iv);

add

# in encrypt mode
my $plaintext = $m->add($ciphertext);
# in decrypt mode
my $ciphertext = $m->add($plaintext);

finish

#encrypt more chunks
$m->start_encrypt($key, $iv);
my $ciphertext = '';
$ciphertext .= $m->add('some data');
$ciphertext .= $m->add('more data');
$ciphertext .= $m->finish;
#decrypt more chunks
$m->start_decrypt($key, $iv);
my $plaintext = '';
$plaintext .= $m->add($some_ciphertext);
$plaintext .= $m->add($more_ciphertext);
$plaintext .= $m->finish;