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;

SEE ALSO

       •   CryptX, Crypt::AuthEnc::CCM, Crypt::AuthEnc::EAX, Crypt::AuthEnc::OCB

       •   <https://en.wikipedia.org/wiki/Galois/Counter_Mode>