Crypt::AuthEnc::XChaCha20Poly1305(3) User Contributed Perl Documentation
NAME
Crypt::AuthEnc::XChaCha20Poly1305 - Authenticated encryption in
XChaCha20-Poly1305 mode
SYNOPSIS
### OO interface
use Crypt::AuthEnc::XChaCha20Poly1305;
my $key = '...';
my $nonce = '...';
my $expected_tag = '...';
# encrypt and authenticate
my $ae_enc = Crypt::AuthEnc::XChaCha20Poly1305->new($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');
my $tag = $ae_enc->encrypt_done();
# decrypt and verify
my $ae_dec = Crypt::AuthEnc::XChaCha20Poly1305->new($key, $nonce);
$ae_dec->adata_add('additional_authenticated_data1');
my $pt = $ae_dec->decrypt_add($ct);
die "decrypt failed" unless $ae_dec->decrypt_done($tag);
### functional interface
use Crypt::AuthEnc::XChaCha20Poly1305 qw(
xchacha20poly1305_encrypt_authenticate
xchacha20poly1305_decrypt_verify
);
my $key = '...';
my $nonce = '...';
my $adata = '...';
my $plaintext = '...';
my ($ciphertext, $tag) = xchacha20poly1305_encrypt_authenticate($key, $nonce, $adata, $plaintext);
my $decrypted = xchacha20poly1305_decrypt_verify($key, $nonce, $adata, $ciphertext, $tag);
DESCRIPTION
Since: CryptX-0.089
Provides encryption and authentication based on XChaCha20 + Poly1305
using the extended 192-bit (24-byte) nonce variant of
ChaCha20-Poly1305.
This is a stateful API. Build one message by calling, in order: "new"
or "set_iv", optional "adata_add", zero or more "encrypt_add" or
"decrypt_add" calls, then "encrypt_done" or "decrypt_done".
Use a fresh object per message. If you construct with new($key) you
must call set_iv($nonce) before adding AAD or processing
plaintext/ciphertext. When verifying, decrypt_done($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", "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::XChaCha20Poly1305 qw(
xchacha20poly1305_encrypt_authenticate
xchacha20poly1305_decrypt_verify
);
FUNCTIONS
xchacha20poly1305_encrypt_authenticate
my ($ciphertext, $tag) = xchacha20poly1305_encrypt_authenticate($key, $nonce, $adata, $plaintext);
# $key ..... [binary string] encryption key (256 bits / 32 bytes)
# $nonce ... [binary string] extended nonce (192 bits / 24 bytes)
# $adata ... [binary string] additional authenticated data (optional)
Invalid key or nonce lengths croak. String-overloaded objects are
accepted for $key and $nonce.
xchacha20poly1305_decrypt_verify
my $plaintext = xchacha20poly1305_decrypt_verify($key, $nonce, $adata,
$ciphertext, $tag);
# on error returns undef
Invalid key or nonce lengths croak. String-overloaded objects are
accepted for $key and $nonce.
METHODS
Unless noted otherwise, assume $ae is an existing AEAD object created
via "new", for example:
my $ae = Crypt::AuthEnc::XChaCha20Poly1305->new($key, $nonce);
new
my $ae = Crypt::AuthEnc::XChaCha20Poly1305->new($key, $nonce);
my $ae = Crypt::AuthEnc::XChaCha20Poly1305->new($key);
# $key ..... [binary string] encryption key (256 bits / 32 bytes)
# $nonce ... [binary string] extended nonce (192 bits / 24 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 $ae = Crypt::AuthEnc::XChaCha20Poly1305->new($key)->set_iv($nonce);
# $nonce ... [binary string] extended nonce (192 bits / 24 bytes)
Call "set_iv" before the first "adata_add", "encrypt_add", or
"decrypt_add" for a message.
clone
Returns a copy of the AEAD object in its current state.
my $ae_new = $ae->clone;
SEE ALSO
o Crypt::AuthEnc::ChaCha20Poly1305(3), Crypt::AuthEnc::GCM(3),
Crypt::AuthEnc::CCM(3)
o <https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-xchacha>
perl v5.34.3 2026-05-11
Crypt::AuthEnc::XChaCha20Poly1305(3)
cryptx 0.89.0 - Generated Tue May 12 14:15:24 CDT 2026