# CYBOU — Sovereign Decentralized Communication Infrastructure

> CYBOU (cybou.fr) is an open C++20 R&D project for sovereign, decentralized and secure communication infrastructure. Messaging is one service within the broader architecture. Multi-validator BFT finality, hybrid post-quantum encryption, storage and full operator-key isolation remain development targets rather than deployed production guarantees.

## System Overview & Current Development Status
- **Project Stage:** Architecture hardening and open research.
- **Not Deployed Infrastructure Today:** The network currently uses an internal development environment. Public releases will follow completion of the multi-validator BFT transition and end-to-end communication stack.
- **Creator:** Stanislav Saveliev.
- **Repository:** https://github.com/cybou-fr/cybou
- **License:** MIT

## Canonical Architecture Specifications
- **Consensus Model:** Explicit Byzantine Fault Tolerance (BFT) with operator-approved validator admission.
- **Validator Weight:** Equal weight for all active validators (`weight = 1`).
- **Byzantine Quorum:** Minimum 4 validators strictly required for $f=1$ malicious/offline fault tolerance ($N \ge 3f + 1$).
- **Proof of Trust (PoT) Epochs:** Deterministic integer-only arithmetic computed strictly from finalized block height. Zero local wall-clock consensus logic to prevent time manipulation.
- **Tokenomics:**
  - `MAX_SUPPLY`: 100,000,000,000 CYBOU (strictly 0 decimals, integer units only).
  - `Onboarding`: Permissionless AccountID creation (`AccountCreateOpV1`) with anti-Sybil proof-of-work (`AccountCreationWorkV1`). An onboarding bonus is credited atomically from `OnboardingPool` to `SystemBalance` (doc 70). No operator vouchers or central approval are required.
  - `Fee Split`: Deterministic size-aware fees without bidding/priority wars. Split ratio is 3:1 (75% to Network Security / Validator Pool, 25% to OnboardingPool reserve).
- **Post-Quantum by Design (PQ by design):**
  - Payload and session encapsulation use the hybrid HPKE standard (RFC 9180): NIST ML-KEM-768 (Kyber) combined with X25519.
  - Defeats "Harvest Now, Decrypt Later" (HNDL) attacks from adversaries capturing encrypted traffic today.
  - Salted content commitment (doc 69): validators only verify transaction inclusion and content commitments; no cleartext or per-mail consensus object exists on-chain.
- **Operator Key Separation (doc 68):**
  - Strict isolation across 4 distinct key domains:
    1. Operator Authority Key
    2. Operator Validator Key
    3. Release Signing Key
    4. Treasury Key
- **Storage Model:**
  - Desktop nodes may prune canonical chain history.
  - Active validators maintain required canonical pre-Store MailTx history.
  - Inbox, Sent, and read-state index trees are owned strictly on the local client machine.
  - Large file attachments defer to future distributed Object Storage.

## Key Source Code References
- `src/cybou/account_creation.h`, `src/cybou/account_creation.cpp`: Permissionless AccountCreateOpV1 and anti-Sybil AccountCreationWorkV1.
- `src/cybou/state.h`, `src/cybou/state.cpp`: Deterministic state transitions, account balance tracking, atomic onboarding bonus, LevelDB persistence.
- `docs/cybou/00_VISION.md`: Scope and architectural principles.
- `docs/cybou/07_BFT_CONSENSUS.md`: Multi-validator BFT consensus engine.
- `docs/cybou/16_MAIL_PROTOCOL.md`: MailTx protocol format and fee rules.
- `docs/cybou/26_IMPLEMENTATION_STATUS.md`: Real-world implementation matrix.
- `docs/cybou/49_EMAIL_E2EE_HPKE_PQ.md`: Hybrid post-quantum HPKE specification.
- `docs/cybou/68_OPERATOR_KEY_SEPARATION.md`: 4-way key domain isolation.
- `docs/cybou/69_MAIL_EVIDENCE_BUNDLE.md`: Inclusion certificates and salted content commitments.
- `docs/cybou/70_ACCOUNT_CREATION_ANTI_SYBIL.md`: Permissionless account creation and anti-Sybil architecture.
- `AGENTS.md`: Authoritative engineering constraints.
- `MANIFEST.md`: SHA-256 integrity inventory of all specification files.