What is Shamir sharing?
Shamir splits one secret into N shares so any M shares rebuild it — with a correct implementation, fewer than M reveal nothing useful. That is different from Multisig (M-of-N keys that co-sign a spend) and from a BIP-39 phrase (one recovery word list — not a threshold split).
When would you use this? Shamir is for backup / inheritance of one secret (split custody of the phrase itself). Multisig is for ongoing spend policy (several keys must sign). This page is a math demo only — format is not SLIP-39 and is not audited for real funds; the “not for real funds” warning is about compatibility and hardening, not “the math is fake.”
| Question | Shamir (this page) | Multisig | BIP-39 phrase |
|---|---|---|---|
| What is split / controlled? | One secret (raw bytes) → N shares | N independent keys (not one secret split) | Nothing is split — one recovery word list |
| What does M-of-N mean? | Any M shares rebuild the same secret | M signatures authorize a spend on a vault address | N/A — phrase is all-or-nothing, not threshold |
| This lab’s format | share:index:hex (educational only) |
Addresses derived from public keys | English BIP-39 wordlist |
Threshold secret sharing ≠ multisig vault (spend policy). Shares here are not SLIP-39 words.
Ops (mental model): store each share in a separate place; M−1 shares should be useless alone.
You do not need a separate note of “M was 2” if you keep the share lines — recombination uses the share
index values (each share’s label / x-coordinate). Cap M,N ≤ 7 is a deliberate UI/demo limit, not a law of Shamir math.
Practice secret
Use a throwaway secret.
Even-length hex is raw bytes (e.g. deadbeef = 4 bytes); other text is UTF-8 (e.g. hello = 5 bytes).
This page never reads your Lab mnemonic — paste practice text only.
Split demo
Defaults 2-of-3. Require 2 ≤ M ≤ N ≤ 7 (demo cap for simple UI).
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Educational only — not SLIP-39. After split, use Verify recombine below to prove any M shares rebuild the practice secret (still offline).
Verify recombine (educational) Paste any M share lines (one per line). Reconstructs the practice secret offline and compares to the field above when it is still filled. Not SLIP-39; never for real funds.
Paste M or more share:index:hex lines (e.g. copy two cards after a 2-of-3 split).
Proves the demo works offline — this is not a production backup tool.
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