Secret Splitter is an app that lets you split a secret (e.g. a password or a message) into X parts. When you later collect at least Y parts, you can fully recover the original secret.
Each generated part looks like gibberish and does not reveal anything about the secret by itself. In fact, having any fewer than Y parts will prevent you from learning anything about the secret.
You can split your password MyP@ssw0rd! into 5 parts, and require 3 parts for password recovery. The app will generate parts for you that look like this:
You can then print each part on a separate piece of paper, and hide the papers around your house, your garden, in your safe, under a rock, etc.
If you forget your password, just collect any 3 of the 5 parts and you can fully recover the password.
If one or two parts get accidentally destroyed, you can still collect the remaining 3 parts to recover the password. If you (or someone else) obtains only 2 parts or fewer, it is not possible to recover the password at all - the parts are completely useless without having all the required pieces.
Secret Splitter's initial screen lets you configure how many parts you want to split your secret into, and how many parts are required to recombine your secret.
You can enter any secret you want - a password, passphrase, GPS coordinates, or a custom message.
Split your secret into a list of random parts. Each part is unique and is cryptographically entangled with other parts from the same list.
To recover your secret, begin by collecting parts and enter them into the app. Only parts that were generated in the same list will work together.
After you have entered the parts, you can proceed to restore the secret.
You can quickly copy and share the restored secret with others, or store it locally in your device.
Help section describes in detail the purpose of Secret Splitter, how to use it, and when you might want to use it.
Secret Splitter fully supports Dark Mode.
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Imagine you have a secret, for example:
The secret is quite long and difficult to remember, and you are rightfully worried you might forget it and loose access to it forever.
With Secret Splitter, you can split your secret into 7 parts, and require at least 4 parts for recovery. You can print all 7 parts and hide them somewhere. Maybe you hide a few in your home, and give some to your partner, parents, friends, etc.
If you ever forget your secret, you can combine any 4 of the 7 parts and fully recover the secret. But your parents, friends and your partner cannot recover the secret unless they retrieve at least 4 parts also. And that's assuming you go the route of telling them in detail the purpose of that little piece of paper with a funny looking code.
There are many situations when you might find this app useful, and here are some additional examples:
This app is using Shamir's Secret Sharing Scheme, which makes it all possible. This scheme has information theoretic security, meaning the scheme cannot be broken even if your adversary has unlimited computing power.
Thus, your adversary might instead try to guess your secret directly, or attack the cryptosystem where you use the secret. Or he might try to collect the required minimum number of parts. But he cannot directly attack the Shamir's scheme by somehow using fewer than the required number of parts and computing the final part.
Our implementation of the Shamir's scheme is a port of an open-source Linux package called libgfshare. This app and libgfshare are using different export formats, but a format conversion would make them fully compatible and interoperable.
The algorithm used to generate parts is:
Inverse this algorithm to recombine the original secret from parts.
It's very simple. Secret Splitter does not collect any data.
No telemetry.
No analytics.
No internet communication whatsoever.
