02 · GF(256) Threshold Math · Offline-Ready
Shamir Secret Sharing (M-aus-N in GF(256)) & Entropie-Labor
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Combinatoric Entropy Estimate
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128 bits
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Comparison of Archival Backup Architectures
| Backup Method | Confidentiality if 1 Card Exposed | Availability if 1 Card Lost | Residual Entropy |
|---|---|---|---|
| Single paper or steel sheet | Full exposure | Permanent loss | 0 bits |
| Two identical full copies | Full exposure (2x surface) | Preserved | 0 bits |
| Naive half-split (6 + 6 words) | Severely degraded | Permanent loss | Drops to ~62–66 bits |
| Shamir 2-of-3 (CF1-2OF3) | 0 bits disclosed | 100% preserved | Full 128 bits |
| Shamir 3-of-5 (CF1-3OF5) | 0 bits up to 2 cards | Survives 2 lost cards | Full 128–256 bits |
Häufig gestellte Fragen (FAQ)
What is Shamir’s M-of-N Threshold Secret Sharing?
Published by Adi Shamir in 1979, it splits a string into N distinct mathematical shares so that any M shares (e.g., 2 of 3) reconstruct the exact secret, while M−1 shares reveal zero bits of information.
Why shouldn’t I just split a 12-word passphrase into two 6-word halves?
Splitting 12 dictionary words into two 6-word sheets drops remaining combinatoric uncertainty from 128 bits down to ~62–66 bits if one sheet is exposed. With 2-of-3 Shamir sharing, a single exposed share still leaves full 128-bit security intact.
Can I run this tool in Airplane Mode?
Yes. Once this page loads in your browser, you can disconnect Wi-Fi and mobile data, generate and print your vault cards, and close the tab before reconnecting.