BLVM Spec Lock

Purpose-built formal verification tool for Bitcoin Commons.

Locking mechanism: See docs/LOCKING_MECHANISM.md for the full lifecycle (discover → enrich → verify), attribute syntax, and status semantics. Spec wording: See SPEC_WORDING.md for parseable condition patterns. How to annotate: See docs/ANNOTATION_GUIDE.md for adding #[spec_locked] to new functions.

Overview

BLVM Spec Lock provides formal verification for Bitcoin consensus code by:

Linking Rust functions to Orange Paper specifications via #[spec_locked] attributes
Verifying contracts (#[requires] and #[ensures]) using static analysis and Z3
Providing a cargo test-like CLI experience

Installation

cd blvm-spec-lock
cargo build --release --bin cargo-spec-lock

The binary will be at target/release/cargo-spec-lock.

To use as a cargo subcommand, create a symlink:

ln -s target/release/cargo-spec-lock ~/.cargo/bin/cargo-spec-lock

Usage

Basic Verification

# Verify all functions with #[spec_locked]
cargo spec-lock verify

# With Orange Paper: derive contracts from spec (required for 0 no-contracts)
cargo spec-lock verify --spec-path path/to/THE_ORANGE_PAPER.md

# Strict mode: fail on partial or no-contracts (for CI gates)
cargo spec-lock verify --strict

# Verify specific file
cargo spec-lock verify src/economic.rs

# Verify by subsystem
cargo spec-lock verify --subsystem economic

# Verify by function name
cargo spec-lock verify --name get_block_subsidy

# Verify by Orange Paper section
cargo spec-lock verify --section 6.1

# Lock status summary (no verification)
cargo spec-lock summary --crate-path .
cargo spec-lock summary --crate-path . --spec-path path/to/THE_ORANGE_PAPER.md

Output Formats

# Human-readable (default)
cargo spec-lock verify

# JSON
cargo spec-lock verify --format json

# JUnit XML (for CI)
cargo spec-lock verify --format junit

Writing Contracts

use blvm_spec_lock::spec_locked;

#[spec_locked("6.1")]
#[requires(height >= 0)]
#[ensures(result >= 0)]
#[ensures(result <= MAX_SUBSIDY)]
pub fn get_block_subsidy(height: u64) -> i64 {
    // Implementation...
}

Related Projects (blvm-spec-lock sibling to blvm-consensus, blvm-spec)

From blvm-spec-lock directory:

# Verify blvm-consensus (140 functions)
cargo run --bin cargo-spec-lock -- verify \
  --spec-path ../blvm-spec/THE_ORANGE_PAPER.md \
  --crate-path ../blvm-consensus

# Verify blvm-node (Dandelion 10.6)
cargo run --bin cargo-spec-lock -- verify \
  --spec-path ../blvm-spec/THE_ORANGE_PAPER.md \
  --crate-path ../blvm-node

With Z3: add --features z3 to the cargo run command.

Validation

Negative test: cargo test wrong_implementation_fails — wrong impl must fail verification.
Spec coverage: cargo spec-lock coverage --spec-path ... — theorems → contracts → parseable %.
Drift: cargo spec-lock check-drift --spec-path ... — unparseable contracts, missing impls.

Spec Wording

Orange Paper conditions must be parseable for verification. See SPEC_WORDING.md for:

Supported patterns (\in {true, false}, extracts lower N bits, etc.)
LaTeX → Rust translation (\land → &, ≥ → >=)
What to avoid (activation heights in conditions, mixed prose)

To add #[spec_locked] to new functions, see docs/ANNOTATION_GUIDE.md.

Features

Function Discovery: Automatically finds all #[spec_locked] functions
Spec-derived Contracts: Orange Paper parser + lexer extract parseable conditions (LaTeX, \text{}, \geq, etc.)
Contract Parsing: Extracts #[requires] and #[ensures] attributes
Static Checking: Fast Rust-based checks for simple properties
Z3 Verification: Full SMT solving for complex properties (requires --features z3)
Flexible Filtering: By file, subsystem, name, or Orange Paper section
Multiple Output Formats: Human-readable, JSON, JUnit XML, Markdown

Z3 Support

Z3 verification requires the z3 feature and system dependencies:

Arch Linux

# Install Z3, LLVM, LLVM libs, and clang (required for bindgen)
sudo pacman -S z3 llvm llvm-libs clang

# Build with Z3 feature
cargo build --features z3 --bin cargo-spec-lock

# Run verification
cargo run --features z3 --bin cargo-spec-lock -- verify

Important: You need both llvm and llvm-libs packages. The llvm package provides static libraries, while llvm-libs provides the shared libraries (.so files) that bindgen needs.

Note: Ensure LLVM and llvm-libs versions match your clang version. If you have clang 21.x, you need llvm 21.x and llvm-libs 21.x. If versions don't match:

sudo pacman -Syu llvm llvm-libs clang  # Update all to matching versions

Other Linux Distributions

For Debian/Ubuntu:

sudo apt-get install libz3-dev libclang-dev
cargo build --features z3 --bin cargo-spec-lock

For other distributions, install:

Z3 development libraries
LLVM and clang (matching versions)
libclang development headers

blvm-spec-lock 0.1.7