👻 ghostcrypt-crypto-core

One memory-safe cryptographic core. Every platform.

The client-side cryptography of GhostCrypt, written once in Rust and compiled to WebAssembly for the browser and to native libraries for mobile and desktop — so every surface runs the same audited code instead of a separate re-implementation.

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✨ What it is

A single Rust crate that implements the full end-to-end-encryption stack a messenger needs, behind one clean interface. The same compiled core powers the web client (via WebAssembly) and the mobile and desktop clients (via a foreign-function interface), which collapses the audit surface from one per platform to one.

This repository contains only the cryptographic core. GhostCrypt's application, servers, and infrastructure are not part of it.

                 ┌─────────────────────────────────────────────┐
   Browser  ◀────┤                                             │
   Android  ◀────┤   ghostcrypt-crypto-core  (one Rust crate)  │
   iOS      ◀────┤   X3DH · Double Ratchet · MLS · AEAD · PQC  │
   Desktop  ◀────┤                                             │
                 └─────────────────────────────────────────────┘
                   WebAssembly  +  native FFI, from one source

🔐 Features

Capability	Detail
X3DH key agreement	Authenticated session setup — the signed-prekey signature is verified on the live path
Double Ratchet	Per-message keys, forward secrecy, and post-compromise security
MLS group messaging	Tree-based group key agreement via OpenMLS
AEAD + KDF	AES-256-GCM with HKDF-SHA-256; HMAC-SHA-256 symmetric ratchet
Post-quantum (optional)	Hybrid ML-KEM-768 + X25519, behind the post-quantum feature flag
Multi-surface bindings	WebAssembly (wasm-bindgen) and FFI (flutter_rust_bridge)
Memory-safe	Built on audited crates: x25519-dalek, ed25519-dalek, RustCrypto, OpenMLS

🚀 Quick start

# Build
cargo build

# Run the full test suite (43 tests)
cargo test

# Include the post-quantum hybrid KEM
cargo test --features post-quantum

⚡ Benchmarks

Reproducible Criterion micro-benchmarks for the operations on the critical path. Run them yourself with ./run-benchmarks.sh. Medians below are from an Apple M-series core (release build):

Operation	Median
AES-256-GCM encrypt (1 KiB)	9.9 µs
AES-256-GCM decrypt (1 KiB)	8.3 µs
HKDF-SHA-256	2.5 µs
Identity keypair generate	23.0 µs
Double Ratchet encrypt (1 KiB)	12.9 µs
Double Ratchet decrypt (1 KiB)	83.3 µs
X3DH initiate (incl. signature verify) / respond	115 / 85 µs
MLS key package generate	118 µs
MLS create group	155 µs
MLS encrypt message (1 KiB)	190 µs

Every per-message operation finishes in tens of microseconds, and even the heaviest group operation in under 0.2 ms — orders of magnitude below network latency.

🧪 Testing

aead · identity · kdf · x3dh · ratchet · mls · pqc · end-to-end
43 tests, 0 failures

The suite includes a negative test (test_x3dh_rejects_unauthentic_signed_prekey) that confirms a forged prekey signature is rejected.

📂 Project structure

src/
├── lib.rs          crate root
├── aead/           AES-256-GCM authenticated encryption
├── kdf/            HKDF-SHA-256 key derivation
├── identity/       identity keys, signed prekeys, one-time prekeys
├── x3dh/           X3DH key agreement (+ prekey-signature verification)
├── ratchet/        Double Ratchet session state machine
├── mls/            MLS group messaging (OpenMLS wrapper)
├── pqc/            hybrid post-quantum KEM (feature-gated)
├── api.rs          FFI surface (flutter_rust_bridge)
└── wasm.rs         WebAssembly surface (wasm-bindgen)
benches/            Criterion benchmarks
tests/              integration tests

🛡️ Security

This is a research reference implementation, and it has not been independently audited. Please do not use it to protect real user data. Primitives come from well-regarded audited crates, the X3DH path authenticates the signed prekey before use, and testing is currently example-based (known-answer and property-based tests are planned). Treat it as a learning and research artifact.

📄 Paper

This crate is the reference implementation accompanying a research paper on single-core, multi-surface architecture for end-to-end encrypted messaging. (Citation to be added.)

⚖️ License

Released under the MIT License © 2026 Mohsin Manzoor Bhat.

_{Built with Rust 🦀 — speak freely.}