X25519 key exchange, AES-256-GCM encryption, forward secrecy, and secure channels

Cryptography

SafeClaw uses modern cryptographic primitives for secure communication between the untrusted gateway zone and the trusted TEE zone.

Secure Channel

The secure channel provides end-to-end encryption with forward secrecy:

Gateway (Zone 1)                    TEE (Zone 2)
    │                                    │
    │── X25519 ephemeral key ──────────→ │
    │← X25519 ephemeral key ────────── │
    │                                    │
    │   HKDF-SHA256(shared_secret)       │
    │   → AES-256-GCM session key        │
    │                                    │
    │── Encrypted message ─────────────→ │
    │← Encrypted response ────────────  │

Key Exchange

pub struct KeyPair {
    // X25519 static key pair
}

pub struct EphemeralKeyPair {
    // X25519 ephemeral key pair (per-session)
}

pub struct PublicKey {
    // X25519 public key
}

pub struct SharedSecret {
    // Derived via X25519 Diffie-Hellman
    // Expanded via HKDF-SHA256
}

Channel Builder

pub struct SecureChannelBuilder {
    // Configure and build a secure channel
}

pub struct SecureChannel {
    // AES-256-GCM encrypted bidirectional channel
}

Encryption

// AES-256-GCM encryption/decryption
pub fn encrypt(key: &[u8; 32], plaintext: &[u8]) -> Result<Vec<u8>>;
pub fn decrypt(key: &[u8; 32], ciphertext: &[u8]) -> Result<Vec<u8>>;
pub fn generate_key() -> [u8; 32];

Forward Secrecy

Each session uses ephemeral X25519 key pairs. Even if a long-term key is compromised, past session data cannot be decrypted because:

Ephemeral keys are generated per-session
Shared secrets are derived from ephemeral keys only
Ephemeral private keys are securely erased after key exchange
Session keys are wiped on session termination

Memory Safety

All cryptographic material uses zeroize for secure erasure:

Private keys are zeroed when dropped
Session keys are zeroed on session termination
Shared secrets are zeroed after key derivation
Plaintext buffers are zeroed after encryption

This prevents sensitive key material from lingering in memory after use.

Dependencies

Prop

Type

Cryptography

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