vauban-claim-verifier

Forensic offline verifier for Vauban Claim Algebra (OSS-13).

Zero Vauban infrastructure dependency — auditors, regulators, and design partners can verify claims without any Vauban API access, SDKs, or network connectivity.

What it verifies

A Vauban Claim encodes a verifiable statement in CBOR format per draft-vauban-claim-algebra-00. This crate checks:

| Check | Description | |---|---| | Signature | Ed25519 over canonical CBOR bytes (if public key provided) | | Anchor inclusion | SHA-256 Merkle proof against a Starknet-anchored batch root | | Temporal frame | valid-from ≤ now ≤ valid-until, issued-at in the past | | Evidence structure | Required fields present for the declared evidence scheme | | Delegation chain | R-1 scope-narrowing invariant (structural check) |

All checks produce a structured VerificationReport with a step-by-step evidence trace.

Usage — Library

use vauban_claim_verifier::{verify_claim_offline, AnchorWitness};

// Offline mode: skip on-chain anchor check (suitable for forensic review)
let claim_cbor: &[u8] = &[/* CBOR bytes from claim.cbor */];
let report = verify_claim_offline(claim_cbor, "draft-vauban-claim-algebra-00")?;

assert!(report.temporal_frame_valid);
println!("{}", serde_json::to_string_pretty(&report)?);

With Ed25519 signature verification:

use vauban_claim_verifier::verify_claim_offline_with_pubkey;

let report = verify_claim_offline_with_pubkey(
    claim_cbor,
    "0xabc123...",  // hex-encoded 32-byte Ed25519 public key
    "draft-vauban-claim-algebra-00",
)?;

With full Merkle anchor witness (on-chain inclusion proof):

use vauban_claim_verifier::{verify_claim_with_anchor, AnchorWitness};

let witness = AnchorWitness::on_chain(
    "0xdeadbeef...",                    // Merkle root (32 bytes hex)
    vec!["0xsibling1...", "0xsibling2..."],  // Merkle path
    3,                                  // leaf index in batch
    891_234,                            // Starknet block number
);

let report = verify_claim_with_anchor(claim_cbor, &witness, None, "draft-vauban-claim-algebra-00")?;

Compute claim hash (the Starknet-anchored leaf value):

use vauban_claim_verifier::claim_hash;

let hash = claim_hash(claim_cbor);  // "0x<sha256 hex>"

Usage — CLI

Requires the cli feature (included by default in the binary release):

# Install
cargo install vauban-claim-verifier --features cli

# Verify a claim file offline
vauban-verify --offline --cbor-file claim.cbor

# Verify with a public key
vauban-verify --offline --cbor-file claim.cbor --pubkey 0xabc123...

# Output as JSON
vauban-verify --offline --cbor-file claim.cbor --output json

# Verify with full Merkle witness
vauban-verify \
  --cbor-file claim.cbor \
  --merkle-root 0xdeadbeef... \
  --merkle-path 0xsibling1...,0xsibling2... \
  --leaf-index 3 \
  --block-number 891234

Features

| Feature | Default | Description | |---|---|---| | std | yes | Standard library (SystemTime for timestamps) | | cli | no | Enable vauban-verify binary (requires std, pulls clap) | | wasm | no | WebAssembly target (uses js_sys::Date for timestamps) |

No-std is supported with default-features = false (timestamps replaced with "unknown").

Security Properties

• #![forbid(unsafe_code)] — no unsafe Rust anywhere in the crate
• Zero network calls — offline mode makes no I/O (anchor check is explicitly opt-in)
• Constant-time comparison — Ed25519 verification via ed25519-dalek (timing-safe)
• Panic-free parsing — all CBOR errors return VerifyError, no panics on malformed input
• Dependency-minimal — 6 production dependencies, all audited crates

Design Principles (OSS-13)

This crate implements the OSS-13 deliverable of SNF V2 Work Package 2. The design constraints are:

1. Zero Vauban dependency: no vauban-claim, no Brain API, no Starknet RPC required
2. Auditor-grade transparency: every check produces a named EvidenceStep in the report
3. Apache 2.0 / MIT dual license: usable by any party without copyleft restrictions
4. WASM-compatible: browser-based verification for design partner integration

Spec Version Support

| Spec version | Status | |---|---| | draft-vauban-claim-algebra-00 | Supported | | draft-vauban-claim-algebra-01 | Supported |

License

Licensed under either of:

• Apache License, Version 2.0 (LICENSE-APACHE)
• MIT license (LICENSE-MIT)

at your option.