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Engineering quantum resistance:
an IPsec case study.

How QuSecure and Cisco core networking jointly secured site-to-site IPsec traffic against the post-quantum threat, without rewriting applications.

A working architecture for protecting IPsec VPN traffic with NIST-finalized post-quantum cryptography, validated by a Cisco Distinguished Architect across production-scale core networking environments.

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IPsec is everywhere, and protecting it from harvest-now-decrypt-later isn't optional

Site-to-site VPNs, branch connectivity, and federal-classification networks all depend on IPsec's cryptographic primitives.

The classical Diffie-Hellman key exchange and RSA signatures that IPsec relies on are both vulnerable to a sufficiently powerful quantum computer. Encrypted traffic captured today can be decrypted later, a real concern for any organization whose network traffic carries data with a long sensitivity window.

Practical deployment patterns covered

  • Hybrid IKEv2 design

    How to deploy hybrid post-quantum + classical key exchange in IKEv2 with backward compatibility for the transition window.

  • Cisco IOS XE integration

    Validated patterns for deploying QuProtect alongside Cisco IOS XE on enterprise core routing platforms.

  • NIST PQC algorithm selection

    Practical guidance on which finalized algorithms (Kyber, Dilithium) fit which IPsec roles, and the trade-offs involved.

  • Performance benchmarks

    Real measurements: throughput impact, handshake latency, and CPU utilization on production-scale Cisco platforms.

  • Runtime crypto-agility

    How to switch algorithms in flight, including failover scenarios and policy-driven enforcement at the gateway.

  • Validation methodology

    The test framework Cisco Distinguished Architects used to verify post-quantum interoperability across heterogeneous IPsec endpoints.

The first practical roadmap for post-quantum IPsec at carrier scale

Most published PQC research stops at lab benchmarks.

This case study goes further, showing how a real Cisco-scale core network can be migrated to post-quantum cryptography incrementally, with measurable performance, without coordinated downtime, and with a path to full PQC compliance once the standards stabilize. The same patterns apply to any IPsec deployment built on Cisco core networking.

Request the full IPsec case study

Tell us about your environment and we'll send the latest version of the white paper, plus a recommendation tailored to your IPsec topology.

What you get

Engineering Quantum Resistance: An IPsec Case Study

White paper · QuSecure and Cisco core networking