Shamir's Secret Sharing split
Split a secret into N shares over GF(256) so that any K of them reconstruct it and fewer than K reveal nothing, computed on your device, nothing kept.
Shamir's Secret Sharing split spreads a typed secret across N shares over GF(256), 5 shares and a threshold of 3 by default. Any K of those shares can rebuild the secret, each printed as a K-of-N share i line followed by hex bytes. N must stay within 2 and 255, K within 2 and N, or the run is refused.
Questions
What do shares and threshold mean?
Shares (N) is the total number of shares produced, default 5; threshold (K) is how many of them are needed to recover the secret, default 3.
What ranges are allowed?
Shares from 2 to 255, threshold from 2 up to shares; anything outside those ranges is refused.
What does one share look like?
One line: K-of-N share i, followed by the share's bytes as hex.
What math is this built on?
Polynomial secret sharing over GF(256), the same finite field AES uses.
Do fewer than K shares reveal anything?
No, by construction fewer than the threshold reveal nothing about the secret.
Can I use this from the command line?
Yes, the same code runs on the page, the CLI and MCP.