#NAME

Crypt::AuthEnc::EAX - Authenticated encryption in EAX mode

#SYNOPSIS

### OO interface
use Crypt::AuthEnc::EAX;

# encrypt and authenticate
my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
$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');
my $tag = $ae->encrypt_done();

# decrypt and verify
my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
$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');
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::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);

my ($ciphertext, $tag) = eax_encrypt_authenticate('AES', $key, $iv, $adata, $plaintext);
my $plaintext = eax_decrypt_verify('AES', $key, $iv, $adata, $ciphertext, $tag);

#DESCRIPTION

EAX is a mode that requires a cipher, CTR and OMAC support and provides encryption and authentication. It is initialized with a random IV that can be shared publicly, additional authenticated data which can be fixed and public, and a random secret symmetric key.

#EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);

#FUNCTIONS

#eax_encrypt_authenticate

my ($ciphertext, $tag) = eax_encrypt_authenticate($cipher, $key, $iv, $adata, $plaintext);

# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $iv ...... unique initialization vector (no need to keep it secret)
# $adata ... additional authenticated data

#eax_decrypt_verify

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

#METHODS

#new

my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv);
#or
my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv, $adata);

# $cipher .. 'AES' or name of any other cipher with 16-byte block len
# $key ..... AES key of proper length (128/192/256bits)
# $iv ...... unique initialization vector (no need to keep it secret)
# $adata ... additional authenticated data (optional)

#adata_add

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

#encrypt_add

$ciphertext = $ae->encrypt_add($data);         # can be called multiple times

#encrypt_done

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

#decrypt_add

$plaintext = $ae->decrypt_add($ciphertext);    # can be called multiple times

#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;

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