1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
package Crypt::AuthEnc::OCB;
use strict;
use warnings;
our $VERSION = '0.068_001';
require Exporter; our @ISA = qw(Exporter); ### use Exporter 5.57 'import';
our %EXPORT_TAGS = ( all => [qw( ocb_encrypt_authenticate ocb_decrypt_verify )] );
our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
our @EXPORT = qw();
use Carp;
$Carp::Internal{(__PACKAGE__)}++;
use CryptX;
# obsolete, only for backwards compatibility
sub aad_add { goto &adata_add }
sub blocksize { return 16 }
sub CLONE_SKIP { 1 } # prevent cloning
1;
=pod
=head1 NAME
Crypt::AuthEnc::OCB - Authenticated encryption in OCBv3 mode
=head1 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, $tag);
=head1 DESCRIPTION
This module implements OCB v3 according to L<https://tools.ietf.org/html/rfc7253>
=head1 EXPORT
Nothing is exported by default.
You can export selected functions:
use Crypt::AuthEnc::OCB qw(ocb_encrypt_authenticate ocb_decrypt_verify);
=head1 FUNCTIONS
=head2 ocb_encrypt_authenticate
my ($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
=head2 ocb_decrypt_verify
my $plaintext = ocb_decrypt_verify($cipher, $key, $nonce, $adata, $ciphertext, $tag);
# on error returns undef
=head1 METHODS
=head2 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
=head2 adata_add
$ae->adata_add($adata); #can be called multiple times
=head2 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)
=head2 encrypt_last
$ciphertext = $ae->encrypt_last($data);
=head2 encrypt_done
$tag = $ae->encrypt_done(); # returns $tag value
=head2 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)
=head2 decrypt_last
$plaintext = $ae->decrypt_last($data);
=head2 decrypt_done
my $tag = $ae->decrypt_done; # returns $tag value
#or
my $result = $ae->decrypt_done($tag); # returns 1 (success) or 0 (failure)
=head2 clone
my $ae_new = $ae->clone;
=head1 SEE ALSO
=over
=item * L<CryptX|CryptX>, L<Crypt::AuthEnc::CCM|Crypt::AuthEnc::CCM>, L<Crypt::AuthEnc::GCM|Crypt::AuthEnc::GCM>, L<Crypt::AuthEnc::EAX|Crypt::AuthEnc::EAX>
=item * L<https://en.wikipedia.org/wiki/OCB_mode>
=item * L<https://tools.ietf.org/html/rfc7253>
=back
=cut
|