ChaCha20 Poly1305 Authenticated Cipher

The `chacha` package provides an implementation of the ChaCha20 Poly1305 authenticated encryption algorithm, designed to be compatible with Node.js's `crypto.createCipheriv()` and `createDecipheriv()` API for AES-GCM mode. It uses the more recent IETF draft for ChaCha20-Poly1305 AEAD, which features a 96-bit nonce, distinct from earlier drafts implemented in systems like BoringSSL (though it offers a 'Legacy Aead' for compatibility). The library supports both a pure JavaScript implementation and optional native bindings for performance in Node.js environments, automatically falling back to pure JS where native bindings are unavailable or explicitly opted out. It exposes APIs for the full AEAD, the ChaCha20 stream cipher, and the Poly1305 message authentication code independently. The current stable version is 2.1.0, and while a specific release cadence isn't published, the active GitHub repository and continuous integration suggest ongoing maintenance and stability.