Question 1

How is this different from just copying the key file?

Accepted Answer

A copy means each holder has the full key — any one of them can reconstruct alone. With Shamir splitting, no individual holder has anything useful: K of them must collude to recover the secret. This raises the bar for compromise and adds redundancy at once.

Question 2

Can I change the threshold later?

Accepted Answer

No. The threshold is baked into the shares at split time. To change K, reconstruct the secret, destroy the old shares, and re-split with the new threshold.

Question 3

What if I lose more than N-K shares?

Accepted Answer

The key is unrecoverable. That is the trade-off: distributing shares makes the key resilient against partial loss, but losing too many is permanent.

Question 4

Is this OpenPGP standard?

Accepted Answer

No. Shamir's Secret Sharing is a separate cryptographic scheme; the shares are not OpenPGP packets. They are PGP Tool's own format. Reconstruct using PGP Tool (or any compatible Shamir implementation) before importing into GnuPG.

Question 5

Does the tool support 1-of-N (anyone can recover)?

Accepted Answer

Yes — a 1-of-N split is just the original key copied into N independent shares. Useful for redundancy with no collusion requirement.

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