Rust port of OmniVox, wire-compatible with the C++ original

Byte-exact cereal binary layout, RFC 8439 ChaCha20-Poly1305, RFC 7914
scrypt defaults; tokio transport preserving the original's observable
behavior (contract B1-B3, B5 quirks included). Parity evidence: golden
C++ vectors in tests/vectors.rs and loopback behavior tests; both
cross-directions verified against the unmodified C++ binaries.

Source: https://git.0xfeedc0de.com/michael/OmniVox

README.md

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+# omnivox-rs
+
+Rust port of [OmniVox](https://git.0xfeedc0de.com/michael/OmniVox), a
+templated encrypted TCP client-server library — **wire-compatible
+byte-for-byte** with the original C++ implementation. A Rust client talks
+to a C++ server and vice versa.
+
+- Async TCP built on tokio
+- ChaCha20-Poly1305 authenticated encryption (RFC 8439)
+- scrypt key derivation (RFC 7914, `N = 2^17, r = 8, p = 1`)
+- Byte-exact cereal `BinaryOutputArchive` field layout
+- Zero `unsafe`
+
+## Wire format
+
+Framing is a `u32` little-endian length prefix. Each message is a
+`AeadPacket`: `nonce[12] || tag[16] || u64 len || ciphertext`. Payloads
+implement the `Cereal` trait, which reproduces cereal's raw-LE field
+encoding (see `PARITY-CONTRACT.md` for the normative spec).
+
+## Usage
+
+```rust
+use omnivox::{OmniVox, Cereal, CodecError, Decision, derive_encrypt_key};
+```
+
+Create an `OmniVox<T>` where `T: Cereal`, set the key (both peers must
+agree), then use `start_server` / `connect_to_server` / `send_to_client`
+/ `send_to_server`. Runnable ports of the original demo apps live in
+`examples/`.
+
+## Parity
+
+`PARITY-CONTRACT.md` is the definition of done: it names the unit of
+parity, the accepted differences, and the original's quirks this port
+deliberately preserves (B1–B3, B5) rather than silently fixing. Parity
+evidence:
+
+- `tests/vectors.rs` — golden vectors generated by the C++ CryptoPP +
+  cereal stack (`reference/cppgen.cpp`); keys, serialization bytes, and
+  AEAD ciphertext/tags must match exactly.
+- `tests/loopback.rs` — runtime behavior clauses of the contract.
+- Differential cross-tests: this crate's binaries were verified talking
+  to the unmodified C++ binaries in both directions over loopback.
+
+## Build & test
+
+```bash
+cargo test          # note: the scrypt vectors use N=2^17 (~1 s, 128 MiB per derivation)
+cargo clippy --all-targets
+cargo run --example omnivox-server   # terminal 1
+cargo run --example omnivox-client   # terminal 2
+```
+
+## License
+
+GPL-3.0-or-later, matching the original OmniVox.