//! Onion request construction, parsing, and response decryption.
//!
//! Implements layered encryption for 3-hop onion routing through the Session
//! service node network. Supports both XChaCha20-Poly1305 and AES-256-GCM
//! encryption modes.
/// Per-hop encryption/decryption using XChaCha20-Poly1305 or AES-256-GCM.
/// Onion request payload builder with layered encryption.
/// Server-side onion request parser for decrypting incoming requests.
/// Client-side response parser for decrypting onion-routed responses.