---
name: "Crypt::Stream::ChaCha"
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::ChaCha"
---

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

Stream cipher ChaCha

## NAME

Crypt::Stream::ChaCha - Stream cipher ChaCha

## SYNOPSIS

```
   use Crypt::Stream::ChaCha;
   # encrypt
   my $key = "12345678901234567890123456789012";  # 32 bytes
   my $nonce  = "123456789012";                      # 12 bytes
   my $enc_stream = Crypt::Stream::ChaCha->new($key, $nonce);
   my $ct = $enc_stream->crypt("plain message");
   # decrypt
   my $dec_stream = Crypt::Stream::ChaCha->new($key, $nonce);
   my $pt = $dec_stream->crypt($ct);
```

## DESCRIPTION

Provides an interface to the ChaCha stream cipher.

## METHODS

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

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

### new

```
 my $stream = Crypt::Stream::ChaCha->new($key, $nonce);
 #or
 my $stream = Crypt::Stream::ChaCha->new($key, $nonce, $counter, $rounds);
 # $key     .. [binary string] 32 or 16 bytes
 # $nonce   .. [binary string] 8 or 12 bytes
 # $counter .. [integer] initial counter value (DEFAULT: 0)
 #             for 12-byte nonces the counter must be <= 0xFFFFFFFF
 # $rounds  .. [integer] 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_key = $stream->keystream($length);
```

### clone

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

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

## SEE ALSO

- •

  Crypt::Stream::XChaCha, Crypt::Stream::RC4, Crypt::Stream::Sober128, Crypt::Stream::Salsa20, Crypt::Stream::Sosemanuk

- •

  \<https://www.rfc-editor.org/rfc/rfc7539\>