Crypt::AuthEnc::GCM(3)

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>