---
name: "Crypt::Stream::XChaCha"
section: "3pm"
platform: "linux"
package: "perl-cryptx"
version: "0.091-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Crypt::Stream::XChaCha"
---

# Crypt::Stream::XChaCha(3pm)

Stream cipher XChaCha20

## NAME

Crypt::Stream::XChaCha - Stream cipher XChaCha20

## SYNOPSIS

```
   use Crypt::Stream::XChaCha;
   # encrypt
   my $key    = "12345678901234567890123456789012";  # 32 bytes
   my $nonce  = "123456789012345678901234";          # 24 bytes
   my $enc_stream = Crypt::Stream::XChaCha->new($key, $nonce);
   my $ct = $enc_stream->crypt("plain message");
   # decrypt
   my $dec_stream = Crypt::Stream::XChaCha->new($key, $nonce);
   my $pt = $dec_stream->crypt($ct);
```

## DESCRIPTION

*Since: CryptX-0.089*

Provides an interface to the XChaCha20 stream cipher, an extended-nonce variant of ChaCha20 using a 192-bit (24-byte) nonce.

## METHODS

Unless noted otherwise, assume `$stream` is an existing stream object created via `"new"`, for example:

```
 my $stream = Crypt::Stream::XChaCha->new($key, $nonce);
```

### new

```
 my $stream = Crypt::Stream::XChaCha->new($key, $nonce);
 #or
 my $stream = Crypt::Stream::XChaCha->new($key, $nonce, $rounds);
 # $key    .. [binary string] 32 bytes
 # $nonce  .. [binary string] 24 bytes
 # $rounds .. [integer] optional, rounds (DEFAULT: 20)
```

### crypt

Encrypts or decrypts data. The output has the same length as the input. Returns a binary string (raw bytes).

The input is converted using Perl's usual scalar stringification. Passing `"undef"` is treated as an empty string with the usual warning, and numeric scalars are stringified before processing.

```
 my $ciphertext = $stream->crypt($plaintext);
 #or
 my $plaintext = $stream->crypt($ciphertext);
```

### keystream

Returns `$length` bytes of raw keystream as a binary string.

The length is taken using Perl's usual numeric coercion. Values that coerce to an oversized unsigned length are rejected as too large.

```
 my $random_bytes = $stream->keystream($length);
```

### clone

Returns a copy of the stream cipher object in its current state.

```
 my $stream2 = $stream->clone;
```

## SEE ALSO

- •

  Crypt::Stream::ChaCha, Crypt::Stream::XSalsa20

- •

  \<https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-xchacha\>