B
Post-quantum TLS readiness
xs4all.nl
Secure today, exposed to harvest-now-decrypt-later
Short answer
As of 2026-11-09, Quantum Aether could not determine whether xs4all.nl negotiates post-quantum key exchange: the server or its firewall rejected our raw TLS probe.
| Grade | B |
|---|---|
| Key exchange | secp256r1 |
| Post-quantum | undetermined (probe blocked, rescan) |
| TLS | TLSv1.3 |
| Hosting network | Amazon.com, Inc. |
| Tranco rank | #6037 |
| Country | 🇳🇱 Netherlands: #15/24 (51.4%) |
From our weekly tracker of the top 10,000 sites, scanned on 2026-11-09 · /adoption
Weekly history
| Week | Grade | Key exchange | Post-quantum |
|---|---|---|---|
| 2026-W46 | B | secp256r1 | undetermined |
| 2026-W45 | B | secp256r1 | no |
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Markdown
[](https://ather-quantum.com/verify/xs4all.nl)