Add Rocq formal verification and coq-of-rust integration

[avrabe]

Add Rocq formal verification and coq-of-rust integration

Context

WSC is a WebAssembly Signature Component that deals with cryptographic operations and security-critical code. This makes it an excellent candidate for formal verification using:

1. Rocq for pure Coq proofs of cryptographic algorithms
2. coq-of-rust for verifying Rust implementation correctness

Proposal

Phase 1: Add Rocq support for cryptographic proofs

1. Add rules_rocq_rust dependency

Update MODULE.bazel:

# Add to dependencies section
bazel_dep(name = "rules_rocq_rust", version = "0.1.0")

# Add to toolchain setup
rocq = use_extension("@rules_rocq_rust//rocq:extensions.bzl", "rocq")
rocq.toolchain(
    version = "2025.01.0",
    strategy = "download",
)
use_repo(rocq, "rocq_toolchains")

register_toolchains("@rocq_toolchains//:rocq_toolchain")

2. Create cryptographic proof structure

mkdir -p proofs/crypto
mkdir -p proofs/signature

3. Add example cryptographic proof

Create proofs/crypto/hash.v:

(** Formal verification of cryptographic hash properties *)
Require Import Arith List.
Require Import Coq.Strings.String.

(** Define hash function properties *)
Module Hash.
  Parameter t : Type.
  Parameter hash : string -> t.
  
  (** Collision resistance *)
  Axiom collision_resistant : forall s1 s2,
    hash s1 = hash s2 -> s1 = s2.
  
  (** Deterministic *)
  Axiom deterministic : forall s,
    hash s = hash s.
End Hash.

(** Example: SHA-256 properties *)
Module SHA256.
  Definition t := nat. (* Simplified - actual would be bytes *)
  
  Definition hash (s : string) : t := 
    (* Placeholder - actual implementation would be verified Rust code *)
    0.
  
  (** Prove collision resistance for our implementation *)
  Lemma sha256_collision_resistant : 
    forall s1 s2, hash s1 = hash s2 -> s1 = s2.
  Proof.
    (* Proof would go here *)
    Admitted.
End SHA256.

4. Add BUILD.bazel for crypto proofs

Create proofs/BUILD.bazel:

load("@rules_rocq_rust//rocq:defs.bzl", "rocq_library", "rocq_proof_test")

rocq_library(
    name = "crypto_proofs",
    srcs = glob(["crypto/*.v", "signature/*.v"]),
)

rocq_proof_test(
    name = "crypto_proofs_test",
    srcs = glob(["crypto/*.v", "signature/*.v"]),
    deps = [":crypto_proofs"],
)

Phase 2: Add coq-of-rust for Rust verification

1. Enable optional OCaml support

Update MODULE.bazel:

# Optional OCaml toolchain for coq-of-rust (QuickChick support)
ocaml = use_extension("@rules_rocq_rust//toolchains:ocaml_extensions.bzl", "ocaml")
ocaml.toolchain(
    version = "5.1.1",
    strategy = "download",
)
use_repo(ocaml, "ocaml_toolchains")

register_toolchains("@ocaml_toolchains//:ocaml_toolchain")

2. Create verified Rust components

mkdir -p verified/crypto

3. Add example verified Rust component

Create verified/crypto/sha256.rs:

// Rust implementation that will be verified with coq-of-rust
pub struct Sha256State {
    // State definition
}

pub fn sha256_update(state: &mut Sha256State, data: &[u8]) {
    // Implementation
}

pub fn sha256_finalize(state: &Sha256State) -> [u8; 32] {
    // Implementation
}

Create verified/crypto/BUILD.bazel:

load("@rules_rocq_rust//coq_of_rust:defs.bzl", "coq_of_rust_library")
load("@rules_rust//rust:defs.bzl", "rust_library")

# Rust library
rust_library(
    name = "sha256_rust",
    srcs = ["sha256.rs"],
)

# Generate Coq proofs from Rust
coq_of_rust_library(
    name = "sha256_coq",
    rust_sources = ["sha256.rs"],
    rust_deps = [":sha256_rust"],
)

# End-to-end verification
rocq_rust_proof(
    name = "sha256_verified",
    rust_target = ":sha256_rust",
)

Benefits

• Mathematical proofs of cryptographic algorithm correctness
• Formal verification of Rust implementation matches specifications
• Enhanced security through formal methods
• Integration with existing rules_wasm_component setup
• Future-proof for advanced verification needs

Priority

High - Security-critical code should have formal verification

Dependencies

• rules_rocq_rust v0.1.0+
• Coq 8.20+ (provided by Rocq Platform)
• Optional: OCaml 5.1.1+ (for coq-of-rust features)

Implementation Order

1. Phase 1: Rocq proofs for cryptographic algorithms
2. Phase 2: coq-of-rust for Rust implementation verification
3. Integrate with CI/CD
4. Document verification process

Related

• rules_rocq_rust repository: https://github.com/pulseengine/rules_rocq_rust
• Rocq Platform: https://github.com/rocq-prover/platform
• coq-of-rust: https://github.com/coq-of-rust/coq-of-rust
• Coq documentation: https://coq.inria.fr/