This code is based on "Collusion Resistant Broadcast Encryption With Short Ciphertexts and Private Keys" paper BGW05 by Dan Boneh

install

npm i

test

npm test

Overview

This is just a POC of an earlier version of broadcast based encryption by Dan Boneh et al. For use in 2023, one should use the newer constructions of broadcast encryption.

• setup a channel of n users, runtime and public key size linear with n (96 bytes per user.)
• create a random subset S of users that will be allowed to decrypt.
• create a random encryption key K and encrypt it. Runtime linear with |S|
• select random users and check that only users in S can decrypt and retrieve K. Run time linear with |S| (4usec per user)

This construction splits the users into shards of size m and splitting S accordingly. You can use the same public key in each shard except for a different gammain each shard. So now all sizes are proportional to the shard size.