Crypt::Mode::CTR - Block cipher mode CTR [Counter mode]

NAME  SYNOPSIS  DESCRIPTION  METHODS  new  encrypt  decrypt  start_encrypt  start_decrypt  add  SEE ALSO 

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NAME

Crypt::Mode::CTR − Block cipher mode CTR [Counter mode]

SYNOPSIS

use Crypt::Mode::CTR;
my $m = Crypt::Mode::CTR−>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');
#decrypt more chunks
$m−>start_decrypt($key, $iv);
my $plaintext = $m−>add($some_ciphertext);
$plaintext .= $m−>add($more_ciphertext);

DESCRIPTION

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

METHODS

new

my $m = Crypt::Mode::CTR−>new($cipher_name);
#or
my $m = Crypt::Mode::CTR−>new($cipher_name, $ctr_mode, $ctr_width);
#or
my $m = Crypt::Mode::CTR−>new($cipher_name, $ctr_mode, $ctr_width, $cipher_rounds);
# $cipher_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>
# $ctr_mode ..... 0 little−endian counter (DEFAULT)
# 1 big−endian counter
# 2 little−endian + RFC3686 incrementing
# 3 big−endian + RFC3686 incrementing
# $ctr_width .... counter width in bytes (DEFAULT = full block width)
# $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);

SEE ALSO

	•		CryptX, Crypt::Cipher
	•		Crypt::Cipher::AES, Crypt::Cipher::Blowfish, ...
	•		<https://en.wikipedia.org/wiki/Block_cipher_mode_of_operation#Counter_.28CTR.29>

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