Telegram Reveals Catchain, a BFT Consensus Algorithm

A Feb. 3 paper authored by Nikolai Durov, a Telegram co-founder, lays out the details of Telegram Open Network's consensus mechanism, named Catchain.

Catchain will work for as long as one third of nodes are not malicious, which is equivalent to the theoretical limit outlined for BFT solutions.

The system focuses on validating each block as it gets created, similar to Cosmos' Tendermint or NEO's dBFT. This in opposition to systems proposed by Ethereum and Cardano, where blocks are easy to produce, but must be then reconciled through fork resolution.

Each new block is created via a block generation round, during which validators have a limited time to agree.

Each validator has a clear role during a block voting procedure, with some creating the blocks, others proposing a block for voting, while the remaining nodes vote on the proposal.

The roles are shifted with each new round, which should ensure the correctness of the procedure.

Telegram is set to have no more than 100 validators for the master chain and from 10-30 for each "Shard chain." According to tests conducted in 2018, a block can be generated every five seconds, undergoing the full consensus procedure each time.

Differences lie in some of the specifics, such as how the nodes communicate with each other.

Simply having each node communicate with every other is very inefficient, which means that each project tried to find its own way of making the process faster.

The commission argues that Telegram conducted an unsanctioned sale of securities.