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package Crypt::AuthEnc::GCM;
use strict;
use warnings;
our $VERSION = '0.087';
require Exporter; our @ISA = qw(Exporter); ### use Exporter 5.57 'import';
our %EXPORT_TAGS = ( all => [qw( gcm_encrypt_authenticate gcm_decrypt_verify )] );
our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
our @EXPORT = qw();
use Carp;
$Carp::Internal{(__PACKAGE__)}++;
use CryptX;
sub CLONE_SKIP { 1 } # prevent cloning
1;
=pod
=head1 NAME
Crypt::AuthEnc::GCM - Authenticated encryption in GCM mode
=head1 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, $tag);
=head1 DESCRIPTION
Galois/Counter Mode (GCM) - provides encryption and authentication.
=head1 EXPORT
Nothing is exported by default.
You can export selected functions:
use Crypt::AuthEnc::GCM qw(gcm_encrypt_authenticate gcm_decrypt_verify);
=head1 FUNCTIONS
=head2 gcm_encrypt_authenticate
my ($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
=head2 gcm_decrypt_verify
my $plaintext = gcm_decrypt_verify($cipher, $key, $iv, $adata, $ciphertext, $tag);
# on error returns undef
=head1 METHODS
=head2 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)
=head2 iv_add
Set initialization vector (IV).
$ae->iv_add($iv_data); #can be called multiple times
=head2 adata_add
Add B<additional authenticated data>.
Can be called B<after> all C<iv_add> calls but before the first C<encrypt_add> or C<decrypt_add>.
$ae->adata_add($aad_data); # can be called multiple times
=head2 encrypt_add
$ciphertext = $ae->encrypt_add($data); # can be called multiple times
=head2 encrypt_done
$tag = $ae->encrypt_done(); # returns $tag value
=head2 decrypt_add
$plaintext = $ae->decrypt_add($ciphertext); # can be called multiple times
=head2 decrypt_done
my $tag = $ae->decrypt_done; # returns $tag value
#or
my $result = $ae->decrypt_done($tag); # returns 1 (success) or 0 (failure)
=head2 reset
$ae->reset;
=head2 clone
my $ae_new = $ae->clone;
=head1 SEE ALSO
=over
=item * L<CryptX|CryptX>, L<Crypt::AuthEnc::CCM|Crypt::AuthEnc::CCM>, L<Crypt::AuthEnc::EAX|Crypt::AuthEnc::EAX>, L<Crypt::AuthEnc::OCB|Crypt::AuthEnc::OCB>
=item * L<https://en.wikipedia.org/wiki/Galois/Counter_Mode>
=back
=cut
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