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;