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Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

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Shamir's Secret Sharing Scheme

Java implementation of Shamir's Secret Sharing Scheme. See the wikipedia article for details on the algorithm. This implementation uses a BigInteger mod-prime polynomial.

Maven

<dependency>
    <groupId>org.mitre.secretsharing</groupId>
    <artifactId>secret-sharing-scheme</artifactId>
    <version>1.2.0</version>
</dependency>

Snapshot builds are available on Sonatype's OSS snapshot repository:

<dependency>
    <groupId>org.mitre.secretsharing</groupId>
    <artifactId>secret-sharing-scheme</artifactId>
    <version>1.3.0-SNAPSHOT</version>
</dependency>

Usage

Splitting a secret byte[] into parts:

byte[] secret = ...;
Part[] parts = Secrets.split(secret);

Reconstructing a secret byte[] from parts:

Parts[] parts = ...;
byte[] secret = Secrets.join(parts);

Converting a Part to a formatted String:

Part part = ...;
String formatted = PartFormats.currentStringFormat().format(part);

Parsing a String to a Part:

String formatted = ...;
Part part = PartFormats.parse(formatted);

Security

Shamir's Secret Sharing Scheme is an information-theoretically secure way to divide a secret into shareable parts. For comparison, key-based cryptographic techniques are computationally secure.

This Java implementation of the scheme has been reviewed by a MITRE cryptographer and found to be sound. However, if you have any doubts, inspect the source code and compile it yourself.

This implementation of Shamir's Secret Sharing Scheme is not subject to export control laws in the United States of America. Please check local laws concerning cryptography before downloading or using this library.

Online Web Implementation

This implementation of the scheme can be used in a web browser. Use it at your own risk! If your secret is truly secret then you shouldn't trust somebody else's webapp, and should instead download, inspect, and compile the code yourself.