perldoc > Crypt::AuthEnc::OCB(3pm)

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📛 NAME

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

🚀 Quick Reference

Use Case	Command	Description
OO Encrypt	$ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len); … $tag = $ae->encrypt_done();	Encrypt plaintext with additional authenticated data
OO Decrypt	$ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len); … $result = $ae->decrypt_done($expected_tag);	Decrypt and verify the tag
Functional Encrypt	($ciphertext, $tag) = ocb_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);	One-shot authenticated encryption
Functional Decrypt	$plaintext = ocb_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);	One-shot decryption; returns undef on failure

📋 SYNOPSIS

### OO interface
use Crypt::AuthEnc::OCB;

# encrypt and authenticate
my $ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len);
$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');
$ct .= $ae->encrypt_last('rest of data');
my $tag = $ae->encrypt_done();

# decrypt and verify
my $ae = Crypt::AuthEnc::OCB->new("AES", $key, $nonce, $tag_len);
$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');
$pt .= $ae->decrypt_last('rest of data');
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::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);

my ($ciphertext, $tag) = ocb_encrypt_authenticate('AES', $key, $nonce, $adata, $tag_len, $plaintext);
my $plaintext = ocb_decrypt_verify('AES', $key, $nonce, $adata, $ciphertext, $tag);

📘 DESCRIPTION

This module implements OCB v3 according to <https://tools.ietf.org/html/rfc7253>

📤 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, $adata, $tag_len, $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)
# $adata ... additional authenticated data
# $tag_len . required length of output tag

🔹 ocb_decrypt_verify

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

🧬 METHODS

🔹 new

my $ae = Crypt::AuthEnc::OCB->new($cipher, $key, $nonce, $tag_len);

# $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)
# $tag_len . required length of output tag

🔹 adata_add

$ae->adata_add($adata);                        # 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();                    # returns $tag value

🔹 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)

🔹 decrypt_last

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

🔹 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;

🔗 SEE ALSO

• CryptX, Crypt::AuthEnc::CCM, Crypt::AuthEnc::GCM, Crypt::AuthEnc::EAX
• <https://en.wikipedia.org/wiki/OCB_mode>
• <https://tools.ietf.org/html/rfc7253>

📛 NAME 🚀 Quick Reference 📋 SYNOPSIS 📘 DESCRIPTION 📤 EXPORT ⚙️ FUNCTIONS 🧬 METHODS 🔗 SEE ALSO