phpMan > perldoc > Crypt::Mode::CBC

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;

SEE ALSO
    *   CryptX, Crypt::Cipher

    *   Crypt::Cipher::AES, Crypt::Cipher::Blowfish, ...

    *   <https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Cipher-block_chaining_.28CBC.2
        9>