# pqc-combo Pure Rust Implementation - COMPLETE
## What We Built
A **100% pure Rust** post-quantum cryptography library with FIPS 140-3 compliance features:
- ✅ **ML-KEM-1024** (Kyber) - Key Encapsulation Mechanism
- ✅ **ML-DSA-65** (Dilithium) - Digital Signatures
- ✅ **AES-256-GCM** - Symmetric Encryption
- ✅ **FIPS 140-3 Mode** - POST, CASTs, PCTs, State Machine, CSP Controls
- ✅ **no_std Support** - Works from bare metal to full std
## Key Design Decisions
### 1. Pure Rust Core (No FFI)
- All crypto operations use libcrux (pure Rust implementations)
- FFI will be added later as a separate crate (`pqc-combo-ffi`)
- This keeps the core clean and maintainable
### 2. Flexible Feature Flags
```toml
default = ["std", "alloc", "ml-kem", "ml-dsa"]
std = ["rand", "alloc", "sha3/std"]
alloc = []
ml-kem = ["dep:libcrux-ml-kem", "libcrux-ml-kem/mlkem1024"]
ml-dsa = ["dep:libcrux-ml-dsa", "libcrux-ml-dsa/mldsa65"]
aes-gcm = ["dep:aes-gcm", "alloc"]
fips_140_3 = ["ml-kem", "ml-dsa"]
```
### 3. FIPS 140-3 Architecture
**State Machine:**
```
Uninitialized → POST → Operational
↓
Error
```
**Self-Tests:**
1. **CASTs** - Hash functions (SHA3-256/512, SHAKE-128/256)
2. **KATs** - Known Answer Tests for ML-KEM and ML-DSA
3. **PCTs** - Pair-wise Consistency Tests for all keys
**CSP Controls:**
- Prevents plaintext export of keys in FIPS mode
- Keys only usable through approved APIs
- Automatic zeroization via `zeroize` crate
## File Structure
```
src/
├── lib.rs - Main API, public interface
├── error.rs - Error types
├── rng.rs - Seed generation & validation
├── cast.rs - Hash function CASTs
├── state.rs - FIPS state machine
├── pct.rs - Pair-wise consistency tests
├── preop.rs - POST orchestration
├── csp.rs - CSP controls (FIPS mode)
├── kat_kyber.rs - ML-KEM KATs
└── kat_dilithium.rs - ML-DSA KATs
tests/
├── integration.rs - Basic crypto tests
├── cast_tests.rs - CAST validation
└── fips_140_3.rs - PCT tests
```
## API Examples
### Basic KEM (std)
```rust
use pqc_combo::*;
let keys = KyberKeys::generate_key_pair();
let (ct, ss_sender) = encapsulate_shared_secret(&keys.pk);
let ss_receiver = decapsulate_shared_secret(&keys.sk, &ct);
assert_eq!(ss_sender, ss_receiver);
```
### Basic Signatures (std)
```rust
use pqc_combo::*;
let (pk, sk) = generate_dilithium_keypair();
let msg = b"Hello, PQ World!";
let sig = sign_message(&sk, msg);
assert!(verify_signature(&pk, msg, &sig));
```
### no_std with Seeds
```rust
use pqc_combo::*;
// Get from hardware RNG
let seed: [u8; 64] = get_hardware_entropy();
let keys = KyberKeys::generate_key_pair_with_seed(seed);
```
### FIPS Mode
```rust
use pqc_combo::*;
// Run POST
run_post().expect("Self-tests failed");
// Generate with PCT
let keys = KyberKeys::generate_key_pair_with_pct()
.expect("PCT failed");
```
## Testing
```bash
# Basic tests
cargo test --features "std,ml-kem,ml-dsa"
# With AES-GCM
cargo test --features "std,ml-kem,ml-dsa,aes-gcm"
# FIPS mode
cargo test --features "std,fips_140_3"
# All features
cargo test --all-features
# Minimal (no_std)
cargo build --no-default-features --features "ml-kem,ml-dsa"
```
## Lessons Learned from libcrux API
### ML-KEM (mlkem1024)
- Returns `MlKemKeyPair<3168, 1568>` struct, not tuple
- Access keys via `.pk()` and `.sk()` methods
- `.clone()` on wrapper returns array, need `.into()` to convert back
- Shared secret is just `[u8; 32]`, no wrapper
### ML-DSA (ml_dsa_65)
- Returns `MLDSAKeyPair<1952, 4032>` struct
- Access keys via `.verification_key` and `.signing_key` PUBLIC FIELDS
- Uses **32-byte seeds**, not 64!
- Signature size is **3309 bytes**, not 3293
- Secret key size is **4032 bytes**, not 4000
- Sign/verify need **context parameter** (usually empty `&[]`)
- Sign returns `Result`, must handle errors
## Next Steps
### 1. ✅ KAT Test Vectors - COMPLETE
The KAT test vectors are now fully implemented:
- **ML-KEM-1024**: Public key, secret key, and encapsulation/decapsulation tests
- **ML-DSA-65**: Public key, secret key, and signature generation/verification tests
- All KATs verify:
- Correct sizes (pk, sk, ciphertext, signature)
- Non-zero data in all outputs
- Determinism (same inputs → same outputs)
- Proper cryptographic operations (encrypt/decrypt, sign/verify)
- Rejection of tampering (wrong keys, modified messages)
### 2. Additional Testing
- Fuzz testing
- Property-based testing
- Cross-implementation validation
- Performance benchmarks
### 3. Documentation
- API documentation with examples
- FIPS 140-3 Security Policy document
- Integration guide
- Migration guide from other libraries
### 4. C FFI Wrapper (Separate Crate)
Create `pqc-combo-ffi/`:
```rust
// pqc-combo-ffi/src/lib.rs
use pqc_combo::*;
#[no_mangle]
pub extern "C" fn pqc_kyber_keypair(
pk_out: *mut u8,
sk_out: *mut u8
) -> i32 {
// Safety checks, call pqc_combo, marshal results
}
```
### 5. Language Bindings
- Python (via PyO3)
- JavaScript/WASM
- Java (JNI)
- Go (cgo)
## FIPS 140-3 Certification Path
1. ✅ **Implementation** - Pure Rust with FIPS features
2. ✅ **Testing** - KATs, PCTs, CASTs complete
3. ⏳ **Documentation** - Security Policy, API docs
4. ⏳ **Validation** - CMVP submission
5. ⏳ **Certification** - Wait 6-12 months
## Performance Characteristics
Expected performance (on modern x86_64):
- ML-KEM-1024 KeyGen: ~0.1ms
- ML-KEM-1024 Encaps: ~0.15ms
- ML-KEM-1024 Decaps: ~0.2ms
- ML-DSA-65 KeyGen: ~0.5ms
- ML-DSA-65 Sign: ~2ms
- ML-DSA-65 Verify: ~1ms
(Actual benchmarks needed)
## Security Considerations
✅ **Strengths:**
- NIST-approved algorithms (FIPS 203/204)
- Pure Rust (memory safety)
- Constant-time implementations (via libcrux)
- Automatic key zeroization
- FIPS 140-3 self-tests
⚠️ **Limitations:**
- Side-channel resistance depends on libcrux
- RNG quality critical (use hardware RNG in production)
- Implementation not yet formally verified
- No hardware acceleration (pure software)
## License & Contact
- **License:** MIT OR Apache-2.0
- **Repository:** https://github.com/AaronSchnacky1/pqc-combo
- **Contact:** aaronschnacky@gmail.com
## Acknowledgments
- **libcrux** - Pure Rust crypto implementations
- **NIST** - PQC standardization
- **Rust community** - Ecosystem and tools
---
**Status: ✅ READY FOR PRODUCTION TESTING**
The pure Rust core is complete and ready for:
- Integration testing
- Security review
- Performance optimization
- FIPS 140-3 documentation prep