Post-Quantum Cryptography (PQC) for Secure Web Gateway Cloud
Post-Quantum Cryptography (PQC) refers to a new generation of cryptographic algorithms designed to secure digital data against the capabilities of future quantum computers.
Traditional encryption methods used across the internet today (such as RSA and ECC) rely on mathematical problems that are practically impossible for standard computers to solve. However, advanced quantum computers will be capable of solving these mathematical problems easily, rendering standard encryption vulnerable. PQC utilizes complex, multi-dimensional mathematical structures (such as lattices) that remain mathematically secure against both standard and quantum computers.
PQC Support in Secure Web Gateway (Cloud) (SSE)
SWG Cloud enables quantum-safe TLS 1.3 cipher suites by default for all TLS inspection starting with SSE 6.8.2 (June 2025). No manual configuration or policy changes are required.
The cloud service automatically negotiates PQC-capable key exchanges when connecting to origin servers and endpoints that support hybrid post-quantum algorithms.
How It Works
When SWG (Cloud) inspects HTTPS traffic, the TLS handshake between the gateway and the destination server uses a hybrid key exchange that combines a classical algorithm with a post-quantum algorithm.
This ensures:
- Backward compatibility — Connections to servers that do not yet support PQC continue to work using classical algorithms.
- Forward security — Traffic encrypted today cannot be decrypted in the future even by quantum computers ("store now, decrypt later" protection).
Supported PQC Algorithms
Key Encapsulation (Key Exchange) - ML-KEM
Skyhigh Security leverages Module-Lattice-Based Key Encapsulation Mechanism (ML-KEM) to handle secure key encapsulation during TLS key exchanges. The following parameter sets are supported:
| Algorithm | Security Level | Use Case |
|---|---|---|
| ML-KEM-512 | NIST Level 1 (128-bit equivalent) | Standard traffic inspection |
| ML-KEM-768 | NIST Level 3 (192-bit equivalent) | Default hybrid key exchange (X25519MLKEM768) |
| ML-KEM-1024 | NIST Level 5 (256-bit equivalent) | High-security workloads |
Digital Signatures - ML-DSA
Skyhigh Security implements Module-Lattice-Based Digital Signature Algorithm (ML-DSA) to validate digital signatures and authenticate certificate authorities. The following parameter variants are supported:
| Algorithm | Security Level |
|---|---|
| ML-DSA-44 | NIST Level 2 |
| ML-DSA-65 | NIST Level 3 |
| ML-DSA-87 | NIST Level 5 |
Default Hybrid Key Exchange
The default ciphersuite negotiated for TLS 1.3 inspection uses:
X25519MLKEM768: A hybrid key exchange combining the classical X25519 ECDH algorithm with ML-KEM-768 for quantum resistance.
This hybrid approach ensures that even if one algorithm is broken, the other still provides protection.
What Administrators Need to Know
| Aspect | Detail |
|---|---|
| Enabled by default? | Yes, since SSE 6.8.2 (June 2025) |
| Configuration required? | No |
| Impact on policy rules? | None - existing web policies continue to work unchanged |
| Performance impact? | Negligible — hybrid key exchange adds minimal overhead to TLS handshakes |
| Client requirements | No client-side changes needed; PQC negotiation is handled server-side by the cloud gateway |
| SSH configuration | Not applicable for Cloud/SSE (SSH PQC configuration is relevant only for On-Prem SWG appliances) |