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.29>