Crypt::AuthEnc::OCB - Authenticated encryption in OCBv3 mode

NAME  SYNOPSIS  DESCRIPTION  EXPORT  FUNCTIONS  ocb_encrypt_authenticate  ocb_decrypt_verify  METHODS  new  adata_add  encrypt_add  encrypt_last  encrypt_done  decrypt_add  decrypt_last  decrypt_done  clone  SEE ALSO 

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NAME

Crypt::AuthEnc::OCB − Authenticated encryption in OCBv3 mode

SYNOPSIS

### OO interface
use Crypt::AuthEnc::OCB;
# encrypt and authenticate
my $ae = Crypt::AuthEnc::OCB−>new("AES", $key, $nonce, $tag_len);
$ae−>adata_add('additional_authenticated_data1');
$ae−>adata_add('additional_authenticated_data2');
my $ct = $ae−>encrypt_add('data1');
$ct .= $ae−>encrypt_add('data2');
$ct .= $ae−>encrypt_add('data3');
$ct .= $ae−>encrypt_last('rest of data');
my $tag = $ae−>encrypt_done();
# decrypt and verify
my $ae = Crypt::AuthEnc::OCB−>new("AES", $key, $nonce, $tag_len);
$ae−>adata_add('additional_authenticated_data1');
$ae−>adata_add('additional_authenticated_data2');
my $pt = $ae−>decrypt_add('ciphertext1');
$pt .= $ae−>decrypt_add('ciphertext2');
$pt .= $ae−>decrypt_add('ciphertext3');
$pt .= $ae−>decrypt_last('rest of data');
my $tag = $ae−>decrypt_done();
die "decrypt failed" unless $tag eq $expected_tag;
#or
my $result = $ae−>decrypt_done($expected_tag); # 0 or 1
### functional interface
use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);
my ($ciphertext, $tag) = ocb_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);
my $plaintext = ocb_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);

DESCRIPTION

This module implements OCB v3 according to <https://tools.ietf.org/html/rfc7253>

EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);

FUNCTIONS

ocb_encrypt_authenticate

my ($ciphertext, $tag) = ocb_encrypt_authenticate($cipher, $key, $nonce, $adata, $tag_len, $plaintext);
# $cipher .. 'AES' or name of any other cipher with 16−byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $nonce ... unique nonce/salt (no need to keep it secret)
# $adata ... additional authenticated data
# $tag_len . required length of output tag

ocb_decrypt_verify

my $plaintext = ocb_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext, $tag);
# on error returns undef

METHODS

new

my $ae = Crypt::AuthEnc::OCB−>new($cipher, $key, $nonce, $tag_len);
# $cipher .. 'AES' or name of any other cipher with 16−byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $nonce ... unique nonce/salt (no need to keep it secret)
# $tag_len . required length of output tag

adata_add

$ae−>adata_add($adata); #can be called multiple times

encrypt_add

$ciphertext = $ae−>encrypt_add($data); # can be called multiple times
#BEWARE: size of $data has to be multiple of blocklen (16 for AES)

encrypt_last

$ciphertext = $ae−>encrypt_last($data);

encrypt_done

$tag = $ae−>encrypt_done(); # returns $tag value

decrypt_add

$plaintext = $ae−>decrypt_add($ciphertext); # can be called multiple times
#BEWARE: size of $ciphertext has to be multiple of blocklen (16 for AES)

decrypt_last

$plaintext = $ae−>decrypt_last($data);

decrypt_done

my $tag = $ae−>decrypt_done; # returns $tag value
#or
my $result = $ae−>decrypt_done($tag); # returns 1 (success) or 0 (failure)

clone

my $ae_new = $ae−>clone;

SEE ALSO

	•		CryptX, Crypt::AuthEnc::CCM, Crypt::AuthEnc::GCM, Crypt::AuthEnc::EAX
	•		<https://en.wikipedia.org/wiki/OCB_mode>
	•		<https://tools.ietf.org/html/rfc7253>

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