NAME

Crypt::AuthEnc::OCB - Authenticated encryption in OCBv3 mode

SYNOPSIS

 ### OO interface
 use Crypt::AuthEnc::OCB;
 
 my $ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce);
 $ae->adata_add('aad1');
 $ae->adata_add('aad2');
 $ct = $ae->encrypt_add($data1);
 $ct = $ae->encrypt_add($data2);
 $ct = $ae->encrypt_add($data3);
 $ct = $ae->encrypt_last('rest of data');
 ($ct,$tag) = $ae->encrypt_done();

 my $ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce);
 $ae->adata_add('aad1');
 $ae->adata_add('aad2');
 $pt = $ae->decrypt_add($data1);
 $pt = $ae->decrypt_add($data2);
 $pt = $ae->decrypt_add($data3);
 $pt = $ae->decrypt_last('rest of data');
 ($pt,$tag) = $ae->decrypt_done();

 ### functional interface
 use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);
 
 my ($ciphertext, $tag) = ocb_encrypt_authenticate('AES', $key, $nonce, $aad, $plaintext);
 my $plaintext = ocb_decrypt_verify('AES', $key, $nonce, $aad, $ciphertext, $tag);

DESCRIPTION

This module implements OCB version 3 according http://datatracker.ietf.org/doc/draft-irtf-cfrg-ocb/

EXPORT

Nothing is exported by default.

You can export selected functions:

  use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);

FUNCTIONS

ocb_encrypt_authenticate

 my ($ciphertext, $tag) = ocb_encrypt_authenticate($cipher, $key, $nonce, $aad, $plaintext);
 
 # $cipher .. 'AES' or name of any other cipher with 16-byte block len
 # $key ..... AES key of proper length (128/192/256bits)
 # $nonce ... unique nonce/salt (no need to keep it secret)
 # $aad ..... meta-data you want to send with the message but not have encrypted

ocb_decrypt_verify

  my $plaintext = ocb_decrypt_verify($cipher, $key, $nonce, $aad, $ciphertext, $tag);
  
  # on error returns undef

METHODS

new

 my $ae = Crypt::AuthEnc::OCB->new($cipher, $key, $nonce);
 
 # $cipher .. 'AES' or name of any other cipher with 16-byte block len
 # $key ..... AES key of proper length (128/192/256bits)
 # $nonce ... unique nonce/salt (no need to keep it secret)

adata_add

 $ae->adata_add($aad);                          #can be called multiple times

encrypt_add

 $ciphertext = $ae->encrypt_add($data);         #can be called multiple times
 
 #BEWARE: size of $data has to be multiple of blocklen (16 for AES)

encrypt_last

 $ciphertext = $ae->encrypt_last($data);

encrypt_done

 $tag = $ae->encrypt_done();

decrypt_add

 $plaintext = $ae->decrypt_add($ciphertext);    #can be called multiple times
 
 #BEWARE: size of $ciphertext has to be multiple of blocklen (16 for AES)

encrypt_last

 $plaintext = $ae->decrypt_last($data);

decrypt_done

 my $result = $ae->decrypt_done($tag);  # returns 1 (success) or 0 (failure)
 #or
 my $tag = $ae->decrypt_done;           # returns $tag value

clone

 my $ae_new = $ae->clone;

SEE ALSO

CryptX, Crypt::Mode::CCM, Crypt::Mode::GCM, Crypt::Mode::EAX

https://en.wikipedia.org/wiki/OCB_mode

cpanm CryptX

perl -MCPAN -e shell
install CryptX