README.md

Shamir Secret Sharing using Galois Field 256

This is a command line application which is an implementation of Shamir Sharing Algorithm coupled with GF256 using NodeJS. The user can make n shares for the original secret key for use minimum k keys to generate the original secret key. It is very secure and uses advanced mathematics to create the secret shares. To use it as an CLI application just add the bin folder to your path environment variable. For more information you can have a look on to:

REFERENCES

1. Shamir Secret_Sharing
2. Finite Field Theory

NOTE: Please take care of the text file formatting where keys are stored or else it may not work properly. Do it exactly as it is given in the examples below.

Setup

Clone the repo, cd into it, and install node package modules.

git clone https://github.com/surajchoubey/SSS_plus_GF256/
cd SSS_plus_GF256/
npm install

Running the program

After getting the above task done, and assuming you have added the bin directory to the environment PATH variable.

To create the N shares and use minimum K shares to unlock

Here you need to take care of 4 parameters passed as arguments.

1. [secret-text] is the original secret key you want to make shares of.
2. [N] is the total number of secret keys you want to generate.
3. [K] is the minimum number of shares you want to use to reproduce the original secret key.
4. [filename] is the name of the file where you want to store all the keys.

General format for running generate_shares CLI application.

generate_shares [secret-text] [N] [K] [filename]

or you can use the below method and all your secret keys are stored in shares.txt in the same directory by default if you leave the argument.

shares.txt from inside looks like this.

1:85,40,44,30,82,14,1,36,48,126,113,96
2:53,74,231,197,65,96,90,6,110,56,60,138
3:138,210,67,144,185,183,244,41,144,132,0,30
4:49,226,154,213,29,216,233,167,65,56,155,86
5:42,86,252,74,129,41,35,151,195,237,109,24
6:25,108,168,30,90,11,176,139,101,121,175,93
7:129,6,50,175,0,79,188,215,76,0,119,130
8:112,108,129,22,248,117,0,159,179,227,137,235
9:234,154,252,104,77,143,227,160,13,76,158,171
10:15,153,249,215,178,141,84,75,90,199,183,106
11:22,177,120,135,193,194,113,24,79,196,142,187
12:165,199,16,211,244,99,253,1,244,13,4,185
13:24,195,83,73,227,10,188,77,157,103,247,178
14:174,152,201,121,212,68,195,152,50,62,81,220
15:144,66,118,205,5,152,68,184,240,248,140,70

Reproducing the original key using atleast K keys

As we generated the keys using generate_shares we can reproduce the original secret key, (illustrated for the word intelligence above). Store the keys labelled by their ID in some file called parts.txt

parts.txt should ideally look like this from inside. In here keys labelled 3, 7 ,8, 10 and 14 (5 minimum keys as set above to reproduce the original secret key).

3:138,210,67,144,185,183,244,41,144,132,0,30
8:112,108,129,22,248,117,0,159,179,227,137,235
14:174,152,201,121,212,68,195,152,50,62,81,220
10:15,153,249,215,178,141,84,75,90,199,183,106
7:129,6,50,175,0,79,188,215,76,0,119,130

Here you need to take care of only one parameter which is passed as argument that is the filename containing the keys.
General format for running rebuild_parts CLI application.

rebuild_parts [filename]

Run the app as CLI using:

or you can use the below method and it will assume to read from parts.txt in the same directory by default if you leave the argument.