// Code Glimpse

Implementing Secret Sharing On A Blockchain Network

Introduction

Secret sharing is a cryptographic algorithm that allows a secret to be divided into parts, called secret shares, which are distributed among a group of participants. These participants can then reconstruct the secret when a minimum number of shares are provided. In this blog post, we will explore the use of secret sharing in the context of a blockchain network and implement a simple secret sharing scheme using Python.

Shamir's Secret Sharing

Shamir's Secret Sharing is a popular secret sharing scheme developed by Adi Shamir in 1979. The main idea behind the scheme is to divide a secret 'S' into 'n' shares in such a way that only a threshold 't' (where t <= n) number of shares can reconstruct the secret 'S'. In this scheme, each share holds a secret point on a polynomial curve that goes through the original secret.

Libraries

We will use the ssss_py library for our implementation. To install the library, run the following command:

pip install ssss_py

Dividing a Secret

To divide a secret using Shamir's Secret Sharing, follow these steps:

  1. Import the SecretSharer class from ssss_py library:
from sss_py import SecretSharer
  1. Define the secret, the number of shares, and the threshold:
secret = "Secret_Blockchain_Data"
n_shares = 5
threshold = 3
  1. Create the secret shares:
shares = SecretSharer.split_secret(secret, threshold, n_shares)
print(shares)

This will produce an output like this:

[(1, '3J6D44XXFDN'), (2, 'AN6E45Z6PGY'), (3, '4SP4YYKFX3W'), (4, '6DR76S6WLXZ'), (5, 'GBY76SAUQU2')]

These shares can now be distributed to the participants in the blockchain network.

Reconstructing the Secret

To reconstruct the original secret from the shares, follow the steps below:

  1. Collect the threshold number of shares from the participants:
t_shares = shares[:threshold]
  1. Use the SecretSharer class to reconstruct the secret:
reconstructed_secret = SecretSharer.recover_secret(t_shares)
print(reconstructed_secret)

This will produce the original secret as output:

"Secret_Blockchain_Data"

The secret has been successfully reconstructed using three shares in this example. If there are fewer than the required threshold shares, the secret cannot be reconstructed, ensuring the integrity and security of the original secret.

Conclusion

In this blog post, we demonstrated the concept of secret sharing in the context of a blockchain network and implemented Shamir's Secret Sharing using Python. Secret sharing can be an effective method for securing sensitive data on a blockchain network by distributing responsibility among multiple participants. By adjusting the threshold and the number of shares, the security and flexibility of the scheme can be tailored to the specific use case.