180 lines
4.6 KiB
Perl
180 lines
4.6 KiB
Perl
package Crypt::AuthEnc::EAX;
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use strict;
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use warnings;
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our $VERSION = '0.048';
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use base qw(Crypt::AuthEnc Exporter);
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our %EXPORT_TAGS = ( all => [qw( eax_encrypt_authenticate eax_decrypt_verify )] );
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our @EXPORT_OK = ( @{ $EXPORT_TAGS{'all'} } );
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our @EXPORT = qw();
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use CryptX;
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use Crypt::Cipher;
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### the following methods/functions are implemented in XS:
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# - _new
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# - DESTROY
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# - clone
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# - encrypt_add
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# - encrypt_done
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# - decrypt_add
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# - decrypt_done
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# - aad_add
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sub new { my $class = shift; _new(Crypt::Cipher::_trans_cipher_name(shift), @_) }
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sub eax_encrypt_authenticate {
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my $cipher_name = shift;
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my $key = shift;
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my $iv = shift;
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my $adata = shift;
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my $plaintext = shift;
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my $m = Crypt::AuthEnc::EAX->new($cipher_name, $key, $iv);
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$m->aad_add($adata) if defined $adata;
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my $ct = $m->encrypt_add($plaintext);
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my $tag = $m->encrypt_done;
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return ($ct, $tag);
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}
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sub eax_decrypt_verify {
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my $cipher_name = shift;
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my $key = shift;
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my $iv = shift;
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my $adata = shift;
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my $ciphertext = shift;
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my $tag = shift;
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my $m = Crypt::AuthEnc::EAX->new($cipher_name, $key, $iv);
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$m->aad_add($adata) if defined $adata;
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my $ct = $m->decrypt_add($ciphertext);
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return $m->decrypt_done($tag) ? $ct : undef;
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}
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sub header_add {
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# obsolete, only for backwards compatibility
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shift->aad_add(@_);
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}
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1;
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=pod
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=head1 NAME
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Crypt::AuthEnc::EAX - Authenticated encryption in EAX mode
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=head1 SYNOPSIS
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### OO interface
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use Crypt::AuthEnc::EAX;
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# encrypt and authenticate
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my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
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$ae->aad_add('additional_authenticated_data1');
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$ae->aad_add('additional_authenticated_data2');
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$ct = $ae->encrypt_add('data1');
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$ct = $ae->encrypt_add('data2');
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$ct = $ae->encrypt_add('data3');
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$tag = $ae->encrypt_done();
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# decrypt and verify
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my $ae = Crypt::AuthEnc::EAX->new("AES", $key, $iv);
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$ae->aad_add('additional_authenticated_data1');
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$ae->aad_add('additional_authenticated_data2');
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$pt = $ae->decrypt_add('ciphertext1');
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$pt = $ae->decrypt_add('ciphertext2');
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$pt = $ae->decrypt_add('ciphertext3');
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$tag = $ae->decrypt_done();
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die "decrypt failed" unless $tag eq $expected_tag;
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#or
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my $result = $ae->decrypt_done($expected_tag) die "decrypt failed";
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### functional interface
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use Crypt::AuthEnc::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);
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my ($ciphertext, $tag) = eax_encrypt_authenticate('AES', $key, $iv, $adata, $plaintext);
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my $plaintext = eax_decrypt_verify('AES', $key, $iv, $adata, $ciphertext, $tag);
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=head1 DESCRIPTION
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EAX is a mode that requires a cipher, CTR and OMAC support and provides encryption and authentication.
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It is initialized with a random IV that can be shared publicly, additional authenticated data which can
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be fixed and public, and a random secret symmetric key.
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=head1 EXPORT
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Nothing is exported by default.
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You can export selected functions:
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use Crypt::AuthEnc::EAX qw(eax_encrypt_authenticate eax_decrypt_verify);
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=head1 FUNCTIONS
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=head2 eax_encrypt_authenticate
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my ($ciphertext, $tag) = eax_encrypt_authenticate($cipher, $key, $iv, $adata, $plaintext);
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# $cipher .. 'AES' or name of any other cipher with 16-byte block len
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# $key ..... AES key of proper length (128/192/256bits)
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# $iv ...... unique initialization vector (no need to keep it secret)
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# $adata ... additional authenticated data
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=head2 eax_decrypt_verify
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my $plaintext = eax_decrypt_verify($cipher, $key, $iv, $adata, $ciphertext, $tag);
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# on error returns undef
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=head1 METHODS
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=head2 new
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my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv);
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#or
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my $ae = Crypt::AuthEnc::EAX->new($cipher, $key, $iv, $adata);
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# $cipher .. 'AES' or name of any other cipher with 16-byte block len
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# $key ..... AES key of proper length (128/192/256bits)
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# $iv ...... unique initialization vector (no need to keep it secret)
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# $adata ... additional authenticated data (optional)
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=head2 aad_add
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$ae->aad_add($adata); #can be called multiple times
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=head2 encrypt_add
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$ciphertext = $ae->encrypt_add($data); #can be called multiple times
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=head2 encrypt_done
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$tag = $ae->encrypt_done();
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=head2 decrypt_add
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$plaintext = $ae->decrypt_add($ciphertext); #can be called multiple times
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=head2 decrypt_done
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my $result = $ae->decrypt_done($tag); # returns 1 (success) or 0 (failure)
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#or
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my $tag = $ae->decrypt_done; # returns $tag value
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=head2 clone
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my $ae_new = $ae->clone;
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=head1 SEE ALSO
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=over
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=item * L<CryptX|CryptX>, L<Crypt::AuthEnc::CCM|Crypt::AuthEnc::CCM>, L<Crypt::AuthEnc::GCM|Crypt::AuthEnc::GCM>, L<Crypt::AuthEnc::OCB|Crypt::AuthEnc::OCB>
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=item * L<https://en.wikipedia.org/wiki/EAX_mode|https://en.wikipedia.org/wiki/EAX_mode>
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=back
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