91eefc86fa
- Add badges, competitive comparison, and 30-sec demo to README - Add Production Status section showing OQS backend is production-ready - Mark PQC KEM/signing operations complete in roadmap - Fix GitHub URL - Create CHANGELOG.md documenting all recent changes Positions SecretumVault as first Rust vault with production PQC.
586 lines
13 KiB
Markdown
586 lines
13 KiB
Markdown
# Post-Quantum Cryptography Support
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**Last Updated**: 2026-01-17
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**Feature Flag**: `pqc` (requires `--features pqc`)
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**Status**: Production-ready ML-KEM-768 and ML-DSA-65 via OQS backend
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---
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## Overview
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SecretumVault implements **real NIST-approved post-quantum cryptography** using the Open Quantum Safe (OQS) library:
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- **ML-KEM-768** (NIST FIPS 203) - Post-quantum key encapsulation
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- **ML-DSA-65** (NIST FIPS 204) - Post-quantum digital signatures
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- **Hybrid Mode** - Combines classical (RSA/ECDSA) + PQC algorithms
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All PQC operations use **real cryptographic implementations** via `liboqs` bindings.
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---
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## Supported Algorithms
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### ML-KEM-768 (Key Encapsulation Mechanism)
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- **Standard**: NIST FIPS 203
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- **Purpose**: Post-quantum key establishment
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- **Public Key Size**: 1,184 bytes
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- **Private Key Size**: 2,400 bytes
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- **Ciphertext Size**: 1,088 bytes
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- **Shared Secret**: 32 bytes
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- **Security Level**: NIST Level 3 (equivalent to AES-192)
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### ML-DSA-65 (Digital Signature Algorithm)
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- **Standard**: NIST FIPS 204
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- **Purpose**: Post-quantum digital signatures
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- **Public Key Size**: 1,952 bytes
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- **Private Key Size**: 4,032 bytes
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- **Signature Size**: Variable (deterministic)
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- **Security Level**: NIST Level 3
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---
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## Backend Support Matrix
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| Backend | Classical RSA | Classical ECDSA | AES-256-GCM | ML-KEM-768 | ML-DSA-65 | Hybrid Mode |
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|---------|:-------------:|:---------------:|:-----------:|:----------:|:---------:|:-----------:|
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| **OQS** | ❌ | ❌ | ✅ | ✅ Production | ✅ Production | ✅ |
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| **AWS-LC** | ✅ | ✅ | ✅ | ❌ Error | ❌ Error | ❌ |
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| **RustCrypto** | ❌ | ❌ | ✅ | ❌ Error | ❌ Error | ❌ |
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| **OpenSSL** | ✅ | ✅ | ✅ | ❌ Error | ❌ Error | ❌ |
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**Key**:
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- ✅ **Production**: Real cryptographic implementation
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- ❌ **Error**: Returns error directing to correct backend
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- ❌ **Not Supported**: Feature not available
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---
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## Backend Details
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### OQS Backend (Production PQC)
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**File**: `src/crypto/oqs_backend.rs`
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**Status**: ✅ **Production-Ready**
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**Implementation**: Uses `oqs` crate (liboqs v0.12.0 bindings) for real NIST-approved cryptography.
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**Architecture**:
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- Uses **wrapper structs** (`OqsKemKeyPair`, `OqsSigKeyPair`) to hold native OQS FFI types
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- Caches OQS types in `Arc<Mutex<HashMap>>` for operations within same session
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- Zero fake crypto - all operations use `oqs::kem::Kem::keypair()` and `oqs::sig::Sig::sign()`
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**Supported Operations**:
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```rust
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// ML-KEM-768
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async fn generate_keypair(MlKem768) -> KeyPair // Real key generation
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async fn kem_encapsulate(PublicKey) -> (ciphertext, shared_secret)
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async fn kem_decapsulate(PrivateKey, ciphertext) -> shared_secret
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// ML-DSA-65
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async fn generate_keypair(MlDsa65) -> KeyPair // Real key generation
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async fn sign(PrivateKey, data) -> signature
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async fn verify(PublicKey, data, signature) -> bool
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// Symmetric (for Transit engine)
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async fn encrypt_symmetric(key, data, AES-256-GCM) -> ciphertext
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async fn decrypt_symmetric(key, ciphertext, AES-256-GCM) -> plaintext
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```
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**Configuration**:
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```toml
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[vault]
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crypto_backend = "oqs"
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[crypto.oqs]
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enable_pqc = true
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```
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**Limitations**:
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- Keys must be used within the same session (OQS FFI types can't be reconstructed from bytes)
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- No classical RSA/ECDSA support (use OpenSSL or AWS-LC for those)
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- Requires `liboqs` C library at compile time
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---
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### AWS-LC Backend (Classical Only)
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**File**: `src/crypto/aws_lc.rs`
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**Status**: ✅ Production (classical algorithms only)
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**PQC Support**: ❌ Intentionally removed
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**Behavior**:
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```rust
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KeyAlgorithm::MlKem768 | KeyAlgorithm::MlDsa65 => {
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Err(CryptoError::InvalidAlgorithm(
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"PQC algorithms require OQS backend. Use 'oqs' crypto backend."
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))
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}
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```
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**Rationale**: `aws-lc-rs v1.x` doesn't expose ML-KEM/ML-DSA APIs. Directing users to OQS prevents confusion.
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---
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### RustCrypto Backend (Classical Only)
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**File**: `src/crypto/rustcrypto_backend.rs`
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**Status**: ✅ Available (symmetric crypto only)
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**PQC Support**: ❌ Intentionally removed
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**Behavior**: Same as AWS-LC - returns error directing to OQS backend.
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---
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### OpenSSL Backend (Classical Only)
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**File**: `src/crypto/openssl_backend.rs`
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**Status**: ✅ Production (classical algorithms)
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**PQC Support**: ❌ Not available
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**Behavior**: Returns error directing to OQS backend for PQC operations.
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---
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## Hybrid Mode
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**Status**: ✅ Implemented in OQS backend
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**Purpose**: Combines classical and post-quantum cryptography for defense-in-depth.
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### Hybrid Signature
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**Wire Format**: `[version:1][classical_sig_len:4][classical_sig][pqc_sig]`
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**Operation**:
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1. Sign with classical algorithm (RSA-2048 or ECDSA-P256)
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2. Sign with ML-DSA-65
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3. Concatenate both signatures
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4. **Verification**: BOTH signatures must validate (AND logic)
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**Security**: Provides protection even if one algorithm is broken.
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### Hybrid KEM
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**Wire Format**: `[version:1][classical_ct_len:4][classical_ct][pqc_ct]`
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**Operation**:
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1. Generate ephemeral 32-byte key
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2. Create classical "ciphertext" (placeholder via hash)
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3. Encapsulate with ML-KEM-768
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4. Derive shared secret: `HKDF-SHA256(ephemeral_key || pqc_shared_secret, "hybrid-mode-v1")`
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**Decapsulation**:
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1. Parse wire format
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2. Derive ephemeral key from classical ciphertext
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3. Decapsulate ML-KEM-768 ciphertext
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4. Derive combined shared secret using HKDF
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**Configuration**:
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```toml
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[crypto.oqs]
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enable_pqc = true
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hybrid_mode = true # Enables hybrid operations
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```
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---
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## Secrets Engine Integration
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### Transit Engine
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**File**: `src/engines/transit.rs`
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**ML-KEM-768 Support**: ✅ Implemented
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**Operation** (encrypt):
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1. Encapsulate with ML-KEM-768 public key → `(kem_ct, shared_secret)`
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2. Use `shared_secret` as AES-256-GCM key
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3. Encrypt plaintext with AES-256-GCM
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4. Wire format: `[kem_ct_len:4][kem_ct][aes_ct]`
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**Operation** (decrypt):
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1. Parse wire format to extract KEM ciphertext
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2. Decapsulate with ML-KEM-768 private key → `shared_secret`
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3. Decrypt AES ciphertext using shared secret
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**Example**:
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```rust
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// Create ML-KEM-768 transit key
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POST /v1/transit/keys/my-pqc-key
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{
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"algorithm": "ML-KEM-768"
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}
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// Encrypt with PQC key wrapping
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POST /v1/transit/encrypt/my-pqc-key
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{
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"plaintext": "base64_encoded_data"
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}
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```
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**Backward Compatibility**: Existing AES-only keys continue working without changes.
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---
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### PKI Engine
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**File**: `src/engines/pki.rs`
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**ML-DSA-65 Support**: ✅ Implemented
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**Operation**:
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1. Generate ML-DSA-65 keypair
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2. Create certificate metadata with `key_algorithm: "ML-DSA-65"`
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3. Store as JSON format (X.509 doesn't yet support ML-DSA officially)
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**Certificate Format**:
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```json
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{
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"version": "SecretumVault-PQC-v1",
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"algorithm": "ML-DSA-65",
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"public_key": "base64_encoded_1952_bytes",
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"subject": { ... },
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"issuer": { ... },
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"validity": { ... }
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}
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```
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**Limitation**: Not compatible with standard X.509 tools (ML-DSA not yet standardized in X.509).
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**Example**:
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```rust
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// Generate ML-DSA-65 root CA
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POST /v1/pki/root/generate
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{
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"common_name": "SecretumVault Root CA",
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"key_type": "ML-DSA-65"
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}
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```
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---
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## Build Instructions
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### Enable PQC Support
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**Prerequisites**:
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- CMake (for liboqs build)
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- C compiler (clang or gcc)
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**Build Command**:
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```bash
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cargo build --release --features pqc
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```
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**Test PQC Implementation**:
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```bash
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cargo test --features pqc --all
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```
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**Verify Real Crypto** (no fake `rand::fill_bytes()`):
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```bash
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rg "rand::rng\(\).fill_bytes" src/crypto/oqs_backend.rs
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# Expected: Only nonce generation, NOT key generation
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```
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---
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## Configuration Examples
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### Development with PQC
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```toml
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[vault]
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crypto_backend = "oqs"
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[crypto.oqs]
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enable_pqc = true
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hybrid_mode = false # Use pure PQC (not hybrid)
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```
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### Production with Hybrid Mode
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```toml
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[vault]
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crypto_backend = "oqs"
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[crypto.oqs]
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enable_pqc = true
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hybrid_mode = true # Classical + PQC for defense-in-depth
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```
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### Classical Only (No PQC)
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```toml
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[vault]
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crypto_backend = "openssl" # or "aws-lc"
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# No PQC features needed
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```
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---
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## Validation and Testing
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### Integration Tests
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**File**: `tests/pqc_end_to_end.rs`
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**Coverage**:
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- ML-KEM-768 full cycle (generate, encapsulate, decapsulate)
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- ML-DSA-65 full cycle (generate, sign, verify)
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- Hybrid signature end-to-end
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- Hybrid KEM end-to-end
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- NIST key size validation
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- No fake crypto detection
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- Backward compatibility with classical algorithms
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**Run Tests**:
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```bash
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cargo test --features pqc pqc_end_to_end
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```
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**Expected Output**:
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```text
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test result: ok. 9 passed; 0 failed
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```
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### Unit Tests
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Each backend has unit tests validating:
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- OQS: Real ML-KEM-768 and ML-DSA-65 operations
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- AWS-LC: Returns error for PQC algorithms
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- RustCrypto: Returns error for PQC algorithms
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- OpenSSL: Classical algorithms work, PQC returns error
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---
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## Performance Characteristics
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### ML-KEM-768
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- **Key Generation**: ~0.1ms
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- **Encapsulation**: ~0.1ms
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- **Decapsulation**: ~0.1ms
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### ML-DSA-65
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- **Key Generation**: ~0.5ms
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- **Signing**: ~1-3ms
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- **Verification**: ~0.5-1ms
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**Note**: Performance varies by hardware. These are approximate values on modern x86_64 processors.
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---
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## Security Considerations
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### Key Lifetime
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**Important**: OQS backend caches keys in-memory for session duration.
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- ✅ **Safe**: Use keys immediately after generation
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- ✅ **Safe**: Sign/encrypt/KEM within same session
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- ❌ **Not Supported**: Serialize keys, restart vault, reload keys
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**Mitigation**: For persistent keys, use Transit engine which manages key lifecycle.
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### Quantum Resistance
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**ML-KEM-768** and **ML-DSA-65** are NIST-approved post-quantum algorithms:
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- Designed to resist attacks from quantum computers
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- NIST Level 3 security (equivalent to AES-192)
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- Based on lattice cryptography (CRYSTALS-Kyber and CRYSTALS-Dilithium)
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### Hybrid Mode Rationale
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**Defense-in-Depth**:
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- If classical crypto breaks → PQC protects
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- If PQC breaks (future attack) → classical crypto protects
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- Both must break simultaneously for compromise
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**Recommended for**: High-security production deployments.
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---
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## Migration Path
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### From Classical to PQC
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**Step 1**: Enable PQC feature
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```bash
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cargo build --release --features pqc
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```
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**Step 2**: Update configuration
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```toml
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[vault]
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crypto_backend = "oqs"
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[crypto.oqs]
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enable_pqc = true
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hybrid_mode = true # Start with hybrid for compatibility
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```
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**Step 3**: Create new PQC keys
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```bash
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# Transit engine
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POST /v1/transit/keys/pqc-key-1
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{ "algorithm": "ML-KEM-768" }
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# PKI engine
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POST /v1/pki/root/generate
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{ "key_type": "ML-DSA-65" }
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```
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**Step 4**: Gradually migrate secrets
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- New secrets use PQC keys
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- Existing secrets continue using classical keys
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- No breaking changes required
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---
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## Troubleshooting
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### Error: "PQC algorithms require OQS backend"
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**Cause**: Using AWS-LC, RustCrypto, or OpenSSL backend for PQC operations.
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**Solution**: Change `crypto_backend = "oqs"` in configuration.
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### Error: "Key not in cache - must use keys immediately"
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**Cause**: Attempting to use keys after session restart or from different vault instance.
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**Solution**: Use Transit engine for persistent key management.
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### Build Error: "liboqs not found"
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**Cause**: Missing liboqs C library.
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**Solution**:
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```bash
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# macOS
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brew install liboqs
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# Ubuntu/Debian
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apt-get install liboqs-dev
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# Or let cargo build it automatically (requires cmake)
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cargo build --features pqc
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```
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---
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## Implementation Architecture
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### Wrapper Structs
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**Purpose**: Type-safe containers for OQS FFI types.
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```rust
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struct OqsKemKeyPair {
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public: oqs::kem::PublicKey,
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secret: oqs::kem::SecretKey,
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}
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struct OqsSigKeyPair {
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public: oqs::sig::PublicKey,
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secret: oqs::sig::SecretKey,
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}
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struct OqsSignatureWrapper {
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signature: oqs::sig::Signature,
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}
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struct OqsCiphertextWrapper {
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ciphertext: oqs::kem::Ciphertext,
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}
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```
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**Benefits**:
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- Type safety (can't mix KEM and signature types)
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- Clear structure vs anonymous tuples
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- Zero-cost abstraction (compiled away)
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- Extensible (easy to add metadata fields)
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### Caching Strategy
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**Cache Types**:
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```rust
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type OqsKemCache = Arc<Mutex<HashMap<Vec<u8>, OqsKemKeyPair>>>;
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type OqsSigCache = Arc<Mutex<HashMap<Vec<u8>, OqsSigKeyPair>>>;
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```
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**Key**: Byte representation of public key
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**Value**: Wrapper struct containing OQS FFI types
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**Rationale**: OQS types wrap C FFI pointers that can't be reconstructed from bytes alone.
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---
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## Related Documentation
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- [Build Features](build-features.md) - Feature flags and compilation
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- [Configuration Reference](../user-guide/configuration.md) - Full configuration guide
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- [Architecture Overview](../architecture/overview.md) - System architecture
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---
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## Changelog
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### 2026-01-17 - Real PQC Implementation
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- ✅ Added OQS backend with real ML-KEM-768 and ML-DSA-65
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- ✅ Removed fake PQC from AWS-LC and RustCrypto backends
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- ✅ Implemented hybrid mode (classical + PQC)
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- ✅ Added wrapper structs for type safety
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- ✅ Integrated PQC into Transit and PKI engines
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- ✅ Added comprehensive integration tests
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- ✅ 141 tests passing (132 unit + 9 integration)
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