#NAME

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

#SYNOPSIS

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

# encrypt and authenticate
my $ae = Crypt::AuthEnc::GCM->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::GCM->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::GCM qw(gcm_encrypt_authenticate gcm_decrypt_verify);

my ($ciphertext, $tag) = gcm_encrypt_authenticate('AES', $key, $iv, $adata, $plaintext);
my $plaintext = gcm_decrypt_verify('AES', $key, $iv, $adata, $ciphertext, $tag);

#DESCRIPTION

Galois/Counter Mode (GCM) - provides encryption and authentication.

#EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::GCM qw(gcm_encrypt_authenticate gcm_decrypt_verify);

#FUNCTIONS

#gcm_encrypt_authenticate

my ($ciphertext, $tag) = gcm_encrypt_authenticate($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 ...... initialization vector
# $adata ... additional authenticated data

#gcm_decrypt_verify

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

#METHODS

#new

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

# $cipher .. 'AES' or name of any other cipher
# $key ..... encryption key of proper length
# $iv ...... initialization vector (optional, you can set it later via iv_add method)

#iv_add

Set initialization vector (IV).

$ae->iv_add($iv_data);                        #can be called multiple times

#adata_add

Add additional authenticated data. Can be called after all iv_add calls but before the first encrypt_add or decrypt_add.

$ae->adata_add($aad_data);                    # 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)

#reset

$ae->reset;

#clone

my $ae_new = $ae->clone;

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