#NAME

Crypt::AuthEnc::ChaCha20Poly1305 - Authenticated encryption in ChaCha20-Poly1305 mode

#SYNOPSIS

### OO interface
use Crypt::AuthEnc::ChaCha20Poly1305;

# encrypt and authenticate
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($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 $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($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::ChaCha20Poly1305 qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);
my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);

#DESCRIPTION

Provides encryption and authentication based on ChaCha20 + Poly1305 as defined in RFC 7539 - https://tools.ietf.org/html/rfc7539

#EXPORT

Nothing is exported by default.

You can export selected functions:

use Crypt::AuthEnc::ChaCha20Poly1305 qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);

#FUNCTIONS

#chacha20poly1305_encrypt_authenticate

my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $iv, $adata, $plaintext);

# $key ..... key of proper length (128 or 256 bits / 16 or 32 bytes)
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)
# $adata ... additional authenticated data (optional)

#chacha20poly1305_decrypt_verify

my $plaintext = chacha20poly1305_decrypt_verify($key, $iv, $adata, $ciphertext, $tag);
# on error returns undef

#METHODS

#new

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $iv);

# $key ..... encryption key of proper length (128 or 256 bits / 16 or 32 bytes)
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

#adata_add

Add additional authenticated data. Can be called before the first encrypt_add or decrypt_add;

$ae->adata_add($aad_data);                     # 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)

#set_iv

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key)->set_iv($iv);
# $iv ...... initialization vector (64 or 96 bits / 8 or 12 bytes)

#set_iv_rfc7905

See https://tools.ietf.org/html/rfc7905

my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key)->set_iv_rfc7905($iv, $seqnum);
# $iv ...... initialization vector (96 bits / 12 bytes)
# $seqnum .. 64bit integer (sequence number)

#clone

my $ae_new = $ae->clone;

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