How many shares do I need?

The threshold that was chosen when they were created. That number is not recorded in the shares themselves, which is why it is worth writing down alongside them. If you are unsure, add shares one at a time until the result reads correctly.

Does the order of the shares matter?

Not at all. The interpolation uses the index carried at the start of each share, so they can be pasted in any sequence and any combination meeting the threshold gives the identical result.

I get gibberish rather than my secret.

Almost always too few shares. It can also be a mistyped character — each share is hexadecimal, so a transposed pair corrupts everything after it. Check the shares against their originals and add another one.

Can I combine shares that came from different secrets?

The tool refuses when the lengths differ, but two same-length sets would combine into nonsense rather than an error. Labelling each set when you create it is the way to avoid mixing them up.

Combine Secret Shares

Rebuild a secret from enough of its shares.

Everything runs inside your browser. Your files never leave your device.

Input

Result

The result appears here as you type.

Ask about Combine Secret Shares

Questions about what this tool does, which option to pick, or what it can and cannot handle.

The question you type here is sent to an AI provider to be answered — your files and whatever you put in the tool above are not, and the assistant cannot see them. Answers are generated and can be wrong. The tool itself is not guessing: it runs deterministic code on your device.

About the Combine Secret Shares

This rebuilds a secret from shares produced by the splitting tool. Paste enough of them, one to a line, and the original comes back exactly.

The reconstruction is Lagrange interpolation over the same finite field the shares were built in. Each share is a point on a curve whose value at zero is the secret; given enough points, that curve is determined and the value at zero can be computed directly. Order does not matter, and which particular shares you hold does not matter — any combination that meets the threshold works identically.

There is one behaviour to understand before you rely on this, and it is the reason the page says so on every result. If you supply fewer shares than the threshold, the tool does not report an error. It produces a different answer. The mathematics is perfectly happy to fit a curve through too few points; there are simply infinitely many curves that fit, and it will find one of them. The output will be the right length and completely wrong.

So the practical check is to read what comes back. A recovered passphrase that reads like a passphrase is almost certainly correct — the odds of a wrong reconstruction producing sensible text are negligible. Output that arrives as unreadable characters, which the tool shows as hexadecimal instead, means you are short a share or one of them was mistyped. That is the failure to expect, and it is why testing recovery at the moment you split something is worth the two minutes it costs.

How to use it

1Paste your shares into the input, one per line. Labels and colons are fine — they are ignored.
2The rebuilt secret appears immediately. There is nothing to configure unless the original was binary rather than text.
3Read the result rather than trusting it. Sensible text means success; hexadecimal usually means a missing share.
4If it looks wrong, add another share and try again — being one short produces a plausible-looking answer rather than an error.

Questions

How many shares do I need?: The threshold that was chosen when they were created. That number is not recorded in the shares themselves, which is why it is worth writing down alongside them. If you are unsure, add shares one at a time until the result reads correctly.
Does the order of the shares matter?: Not at all. The interpolation uses the index carried at the start of each share, so they can be pasted in any sequence and any combination meeting the threshold gives the identical result.
I get gibberish rather than my secret.: Almost always too few shares. It can also be a mistyped character — each share is hexadecimal, so a transposed pair corrupts everything after it. Check the shares against their originals and add another one.
Can I combine shares that came from different secrets?: The tool refuses when the lengths differ, but two same-length sets would combine into nonsense rather than an error. Labelling each set when you create it is the way to avoid mixing them up.