CryptoVerif and Tamarin models, minor doc updates

Signed-off-by: Kamal Tufekcic <kamal@lo.sh>

cryptoverif/README.md

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+# CryptoVerif Models
+
+Computational formal verification of the Soliton cryptographic protocol using
+[CryptoVerif](https://bblanche.gitlabpages.inria.fr/CryptoVerif/).
+
+These models were authored by the protocol designers and have not undergone
+independent peer review. They are published for transparency and to facilitate
+third-party verification. All results are machine-checkable and reproducible.
+
+## Requirements
+
+- CryptoVerif 2.12+
+- The `pq.cvl` library (ships with CryptoVerif)
+
+## Usage
+
+```bash
+# All models
+CV_LIB=/path/to/pq ../verify.sh cryptoverif
+
+# Single model
+cryptoverif -lib /path/to/pq LO_Auth.cv
+```
+
+## Resource Usage
+
+All 5 models complete in under 5 seconds total with negligible RAM usage.
+No special hardware required.
+
+## Results
+
+Verified with CryptoVerif 2.12.
+
+### LO_Auth.cv — Theorem 6 (Key Possession)
+
+| Query | Result | Bound |
+|-------|--------|-------|
+| event(ServerAccepts) ==> event(ClientResponds) | proved | Ns × P_mac + P_kem |
+| inj-event(ServerAccepts) ==> inj-event(ClientResponds) | proved | Ns × P_mac + P_kem |
+
+Primitives: IND-CCA2 KEM (X-Wing), SUF-CMA deterministic MAC (HMAC-SHA3-256).
+
+### LO_KEX.cv — Theorem 2b (Initiator Authentication)
+
+| Query | Result | Bound |
+|-------|--------|-------|
+| event(Bob_Accept) ==> event(Alice_Init) | proved | P_sig_A |
+
+Primitives: EUF-CMA signature (HybridSig). Proof uses only Alice's signature
+unforgeability. Non-injective (replay is application-layer per §7.5 A4).
+
+### LO_KEX_Secrecy.cv — Theorem 1 (Session Key Secrecy)
+
+| Query | Result | Bound |
+|-------|--------|-------|
+| secret rk_A [cv_onesession] | proved | 2·P_prf + 2·P_kem_ik + 2·P_kem_spk + 2·P_kem_opk + collision terms |
+
+Primitives: 3× IND-CCA2 KEM, PRF (HKDF). Signatures omitted (Theorem 1 is
+secrecy, not authentication). No corruption oracles (Tamarin covers corruption
+cases). See header comment for full simplifications list.
+
+### LO_Ratchet_MsgSecrecy.cv — Theorem 3 (Message Key Secrecy)
+
+| Query | Result | Bound |
+|-------|--------|-------|
+| secret test_mk [cv_onesession] | proved | 2 × P_prf |
+
+Precondition: epoch key ek is fresh (from Theorem 1 + KDF_Root output
+independence). Combined with AEAD IND-CPA+INT-CTXT under random keys
+(standard [BN00] composition), gives full message secrecy.
+
+### LO_Stream_Secrecy.cv — Theorem 13, Properties 1+2 (Streaming AEAD)
+
+| Query | Result | Bound |
+|-------|--------|-------|
+| secret b0 [cv_bit] (IND-CPA) | proved | 2·P_ctxt + 2·P_cpa(time, N_enc) |
+| inj-event(Received) ==> inj-event(Sent) (INT-CTXT) | proved | P_ctxt |
+
+Adapted from CryptoVerif's TLS 1.3 Record Protocol example. Nonce uniqueness
+enforced via table-based game hypothesis (§9.11(f)). base_nonce is public.
+
+Key properties of the bounds:
+- **INT-CTXT has no Q-factor** — direct forgery reduction
+- **IND-CPA scales as N_enc × P_cpa** — Q-step hybrid argument
+
+## Scope and Limitations
+
+- **X-Wing as black box**: All models treat X-Wing as a monolithic IND-CCA2
+  KEM. The spec (§2.1) recommends opening the combiner for CryptoVerif. The
+  black-box assumption is stronger; bounds are in terms of P_kem rather than
+  component advantages (P_mlkem + P_x25519 + P_sha3_ro).
+- **No corruption oracles**: The CryptoVerif KEX models prove security for
+  the no-corruption case. Corruption-parameterized secrecy (partial key
+  compromise, RNG corruption) is verified by the Tamarin models.
+- **Simplified KDF info**: LO_KEX_Secrecy.cv binds fewer values in the PRF
+  input than the full HKDF info field. The PRF proof holds regardless of
+  info content; session-binding properties are verified by Tamarin.
+- **Single-epoch message secrecy**: LO_Ratchet_MsgSecrecy.cv assumes a fresh
+  epoch key. The composition chain (Theorem 1 → KDF_Root → fresh ek → PRF →
+  fresh mk → AEAD) is sound but not mechanically verified end-to-end.
+- **No Theorem 2c/d**: Key confirmation requires a combined KEX+Ratchet model.
+
+## Theorem Coverage
+
+| Theorem | Model | What's proved |
+|---------|-------|---------------|
+| 1 (KEX Key Secrecy) | LO_KEX_Secrecy | rk indistinguishable from random |
+| 2b (Initiator Auth) | LO_KEX | σ_SI authentication via EUF-CMA |
+| 3 (Message Secrecy) | LO_Ratchet_MsgSecrecy | mk indistinguishable from random |
+| 6 (Auth Key Possession) | LO_Auth | Correspondence + injective |
+| 13 P1 (IND-CPA) | LO_Stream_Secrecy | Bit secrecy of challenge bit |
+| 13 P2 (INT-CTXT) | LO_Stream_Secrecy | Injective correspondence |