Cryptographic Background

drand is an efficient randomness beacon daemon that utilizes pairing-based cryptography, 𝑡-of-𝑛 distributed key generation, and threshold BLS signatures to generate publicly-verifiable, unbiasable, unpredictable, distributed randomness.

This is an overview of the cryptographic building blocks drand uses to generate publicly-verifiable, unbiasable, and unpredictable randomness in a distributed manner.

The drand beacon has two phases: a setup phase and a beacon phase. Generally, we assume that there are n participants, out of which at most f<n are malicious. drand relies heavily on threshold cryptography primitives, where (at minimum) a threshold of t-f+1 nodes work together to successfully execute cryptographic operations.

Threshold cryptography has many applications as it avoids single points of failure. One application is cryptocurrency multi-sig wallets, where t-of-n participants are required to sign a transaction using a threshold signature scheme.