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Pluggable Cryptography

NTL’s most important security design decision: cryptography is a module, not a foundation.

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The Problem with Hardcoded Crypto

Every major protocol today has cryptographic assumptions baked into its core:
  • TLS uses RSA or ECDSA for key exchange
  • Bitcoin uses secp256k1 for signatures
  • Ethereum uses ECDSA with keccak256
  • HTTPS certificates depend on RSA/ECC
When quantum computing breaks these schemes (not if — when), every protocol that hardcoded them faces an existential rewrite.

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NTL’s Approach

NTL defines a CryptoModule interface that all cryptographic operations go through: 
trait CryptoModule: Send + Sync {
    /// Generate a new keypair
    fn generate_keypair(&self) -> Result<(PublicKey, PrivateKey)>;

    /// Sign a signal
    fn sign(&self, data: &[u8], private_key: &PrivateKey) -> Result<Signature>;

    /// Verify a signature
    fn verify(&self, data: &[u8], signature: &Signature, public_key: &PublicKey) -> Result<bool>;

    /// Encrypt data for a recipient
    fn encrypt(&self, data: &[u8], recipient_public_key: &PublicKey) -> Result<Vec<u8>>;

    /// Decrypt data
    fn decrypt(&self, data: &[u8], private_key: &PrivateKey) -> Result<Vec<u8>>;

    /// Key exchange for synapse establishment
    fn key_exchange(
        &self,
        local_private: &PrivateKey,
        remote_public: &PublicKey,
    ) -> Result<SharedSecret>;

    /// Hash function
    fn hash(&self, data: &[u8]) -> Result<Hash>;

    /// Module identifier
    fn module_id(&self) -> &str;
}

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Default Implementation

NTL ships with a default PostQuantumModule that uses:
OperationAlgorithmStandard
SignaturesCRYSTALS-DilithiumNIST PQC
Key ExchangeCRYSTALS-KyberNIST PQC
EncryptionAES-256-GCM (symmetric)NIST
HashingBLAKE3—
These are the current NIST Post-Quantum Cryptography standards. When they’re superseded, a new module is published — the protocol doesn’t change.

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Swapping Modules

[crypto]
module = "post-quantum"  # Default
# module = "classical"   # RSA/ECDSA for legacy compatibility
# module = "hybrid"      # PQ + classical for transition period
# module = "custom"      # Your implementation
Nodes can negotiate crypto modules during synapse handshake. If two nodes support different modules, they fall back to the highest common module or refuse the synapse.

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Hybrid Mode

During the transition period (now), NTL supports a hybrid mode that signs and encrypts with both classical and post-quantum algorithms. This provides backward compatibility with systems that don’t yet support PQ crypto while maintaining quantum resistance. 
// Hybrid signature: valid if EITHER scheme verifies
// (protects against implementation bugs in new PQ schemes)
HybridSignature {
    classical: Ed25519Signature,
    post_quantum: DilithiumSignature,
}