Crypt::AuthEnc::ChaCha20Poly1305(3) User Contributed Perl Documentation
NAME
Crypt::AuthEnc::ChaCha20Poly1305 - Authenticated encryption in
ChaCha20-Poly1305 mode
SYNOPSIS
### OO interface
use Crypt::AuthEnc::ChaCha20Poly1305;
my $key = '...';
my $nonce = '...';
my $expected_tag = '...';
# encrypt and authenticate
my $ae_enc = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $nonce);
$ae_enc->adata_add('additional_authenticated_data1');
$ae_enc->adata_add('additional_authenticated_data2');
my $ct = $ae_enc->encrypt_add('data1');
$ct .= $ae_enc->encrypt_add('data2');
$ct .= $ae_enc->encrypt_add('data3');
my $tag = $ae_enc->encrypt_done();
# decrypt and verify
my $ae_dec = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $nonce);
$ae_dec->adata_add('additional_authenticated_data1');
$ae_dec->adata_add('additional_authenticated_data2');
my $pt = $ae_dec->decrypt_add('ciphertext1');
$pt .= $ae_dec->decrypt_add('ciphertext2');
$pt .= $ae_dec->decrypt_add('ciphertext3');
$ae_dec->decrypt_done($expected_tag) or die "decrypt failed"; # constant-time tag check
#or, if you need the computed tag, compare it with slow_eq from Crypt::Misc
#(Perl's 'eq' is not constant-time and leaks timing information)
my $computed_tag = $ae_dec->decrypt_done();
die "decrypt failed" unless Crypt::Misc::slow_eq($computed_tag, $expected_tag);
### functional interface
use Crypt::AuthEnc::ChaCha20Poly1305 qw(chacha20poly1305_encrypt_authenticate chacha20poly1305_decrypt_verify);
my $key = '...';
my $nonce = '...';
my $adata = '...';
my $plaintext = '...';
my ($ciphertext, $tag) = chacha20poly1305_encrypt_authenticate($key, $nonce, $adata, $plaintext);
my $decrypted = chacha20poly1305_decrypt_verify($key, $nonce, $adata, $ciphertext, $tag);
DESCRIPTION
Provides authenticated encryption with ChaCha20-Poly1305 as defined in
RFC 7539 <https://www.rfc-editor.org/rfc/rfc7539>.
This is a stateful API. Build one message by calling, in order: "new"
or "set_iv", optional "adata_add", zero or more "encrypt_add" or
"decrypt_add" calls, then "encrypt_done" or "decrypt_done".
Use a fresh object per message. If you construct with new($key) you
must call set_iv($iv) before adding AAD or processing
plaintext/ciphertext. When verifying, decrypt_done($expected_tag) is
the safer one-step form; decrypt_done() without arguments only returns
the calculated tag. The first "encrypt_done" / "decrypt_done" call
finalizes the object. After that, further "set_iv", "set_iv_rfc7905",
"adata_add", "encrypt_add", "decrypt_add", "encrypt_done", and
"decrypt_done" calls croak.
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, $nonce, $adata, $plaintext);
# $key ..... [binary string] key of proper length (128 or 256 bits / 16 or 32 bytes)
# $nonce ... [binary string] nonce (64 or 96 bits / 8 or 12 bytes)
# $adata ... [binary string] additional authenticated data (optional)
chacha20poly1305_decrypt_verify
my $plaintext = chacha20poly1305_decrypt_verify($key, $nonce, $adata, $ciphertext, $tag);
# on error returns undef
METHODS
Unless noted otherwise, assume $ae is an existing AEAD object created
via "new", for example:
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $nonce);
new
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key, $nonce);
#or
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key);
# $key ..... [binary string] encryption key of proper length (128 or 256 bits / 16 or 32 bytes)
# $nonce ... [binary string] nonce (64 or 96 bits / 8 or 12 bytes)
adata_add
Add additional authenticated data. Can be called only before the first
"encrypt_add" or "decrypt_add". Returns the object itself (for
chaining).
$ae->adata_add($aad_data); # can be called multiple times
encrypt_add
Returns a binary string of ciphertext (raw bytes).
my $ciphertext = $ae->encrypt_add($data); # can be called multiple times
encrypt_done
Returns the authentication tag as a binary string (raw bytes). This
call finalizes the current message.
my $tag = $ae->encrypt_done(); # returns $tag value
decrypt_add
Returns a binary string of plaintext (raw bytes).
my $plaintext = $ae->decrypt_add($ciphertext); # can be called multiple times
decrypt_done
Without argument returns the computed tag as a binary string. With $tag
argument returns 1 (success) or 0 (failure). This call finalizes the
current message.
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($nonce);
# $nonce ... [binary string] nonce (64 or 96 bits / 8 or 12 bytes)
Call "set_iv" before the first "adata_add", "encrypt_add", or
"decrypt_add" for a message.
set_iv_rfc7905
See RFC 7905 <https://www.rfc-editor.org/rfc/rfc7905>.
my $ae = Crypt::AuthEnc::ChaCha20Poly1305->new($key)->set_iv_rfc7905($nonce, $seqnum);
# $nonce ... [binary string] nonce (96 bits / 12 bytes)
# $seqnum .. [integer] 64-bit integer (sequence number)
clone
Returns a copy of the AEAD object in its current state.
my $ae_new = $ae->clone;
SEE ALSO
o CryptX(3), Crypt::AuthEnc::XChaCha20Poly1305(3),
Crypt::AuthEnc::GCM(3), Crypt::AuthEnc::CCM(3),
Crypt::AuthEnc::EAX(3), Crypt::AuthEnc::OCB(3)
o <https://www.rfc-editor.org/rfc/rfc7539>
perl v5.34.3 2026-06-18
Crypt::AuthEnc::ChaCha20Poly1305(3)
cryptx 0.90.0 - Generated Sun Jun 21 14:12:52 CDT 2026