Harvest-Now, Decrypt-Later is an adversary strategy where encrypted traffic is captured today and stored until stronger decryption (e.g., quantum) becomes available.

Why are internal networks at risk?

Internal TLS, IPSec, SSH, and vendor tunnels may lag on TLS 1.3/PFS and modern suites, making captured traffic easier to decrypt later.

What is the fastest risk reducer?

Run a cryptographic audit to build a CBOM, enable TLS 1.3 with PFS, modernize IPSec/SSH KEX, and begin a post-quantum migration plan.

Harvest-Now, Decrypt-Later (HNDL): How to Protect Internal Traffic | SafeCipher

Post-Quantum Readiness

Harvest-Now, Decrypt-Later (HNDL): Protecting Your Internal Traffic

HNDL is the practice of capturing encrypted traffic today to decrypt later. To defend internal networks, organisations need a clear cryptographic inventory (CBOM), TLS 1.3 with Perfect Forward Secrecy, hardened IPSec/SSH, and a practical post-quantum roadmap.

Request an Intro Call Cryptographic Audit & CBOM

We sign a mutual NDA before any document exchange. Balanced support for European and North American programmes.

Why HNDL Matters to Internal Networks

Even when internet-facing endpoints are modern, internal systems often trail behind—older TLS versions, inconsistent cipher suites, or bespoke vendor tunnels. That lag increases the chance that captured traffic could be decrypted later, especially for long-lived data (IP, regulated PII, safety telemetry).

Where the Risk Lives: TLS, IPSec, SSH & Appliance Tunnels

TLS inside the perimeter

Prefer TLS 1.3 with mandatory PFS (ephemeral ECDHE/HRR flow).
Eliminate TLS 1.0/1.1; minimise TLS 1.2 and disable static RSA key exchange.
Rotate server certs more frequently; enforce issuer pinning where feasible.

Hardened vendor tunnels

Scrutinise HSM/Key management appliances using custom TLS stacks.
Verify suite parity with policy; prefer audited, standard libraries.
Require patch cadence and third-party security testing.

IPSec (IKEv2)

Use strong Diffie-Hellman groups (e.g., 19/20/21 or better), no static RSA KEX.
Adopt modern PRFs/ciphers; rotate IKE/child SAs aggressively.
Plan for hybrid/post-quantum KEMs as they mature.

SSH

Prefer modern KEX (curve25519-sha256) and strong MACs.
Reduce long-lived host keys; enable key rotation and certificate-based SSH where suitable.
Phase out legacy RSA/DSA auth; enforce strong client policies.

Immediate Actions: HNDL Mitigation Checklist

Create a CBOM: inventory algorithms, key sizes, cipher suites, libraries, certificates, trust anchors, OCSP/CRL across code, infra, devices.
Enforce TLS 1.3 with PFS for internal services; disable static RSA key exchange.
Standardise cipher suites and disable weak/legacy options in load balancers, proxies, service mesh.
Harden IPSec/SSH: modern KEX, short lifetimes, rotate keys, remove deprecated algorithms.
Audit vendor tunnels (HSMs, KMS, appliances); require documented suites and patch SLAs.
Shorten certificate lifetimes, enable issuer pinning where appropriate, and improve revocation propagation.
Data classification: prioritise long-retention or regulated data flows for remediation.
Logging & monitoring: track handshake suites; alert on policy violations.
Begin a post-quantum plan: pilot hybrid signatures/KEMs in low-risk segments to validate performance and compatibility.

Roadmap: From Audit to Post-Quantum Readiness

1) Discovery & CBOM

Automated discovery across repositories, containers, services, certificates, and device images. Identify legacy crypto and misconfigurations.

2) Risk & Quick Wins

Prioritise by exposure, sensitivity, and change effort. Ship config/library upgrades first to reduce HNDL risk rapidly.

3) Policy & PKI Refresh

Align profiles, EKUs, lifetimes, and revocation. Introduce crypto-agility (shorter lifetimes, rotation, issuer pinning).

4) Post-Quantum Pilots

Evaluate hybrid algorithms and KEMs; validate performance and compatibility; plan staged rollouts across environments.

How SafeCipher Can Help

Cryptographic Audit (CBOM): code, cloud, on-prem, and device coverage — learn more
Policy & PKI Refresh: profiles, issuance, revocation, and operations — PKI Services
Architecture Support: hybrid/cloud/OT/IIoT PKI — PKI Design & Architecture
Quantum Transition: pragmatic PQC roadmap and pilots — Quantum PKI Transition
HSM & Cloud HSM: design, vendors, and operations — Cloud HSM, HSM Services, HSM Support, HSM Vendors

Ready to Reduce HNDL Risk?

Start with a brief introductory call. We’ll align goals, sign a mutual NDA, and propose a scoped, not-to-exceed discovery plan that fits your environment.

Request an Intro Call Call: +44 (0) 7498 045 184

We work with teams across Europe and North America; programmes are tailored to local regulations and operational constraints.