Tying it all together, the consensus layer of SSV is based on the Istanbul Byzantine Fault Tolerance (IBFT) algorithm. The algorithm randomly selects a validator node (KeyShare) responsible for block proposal and sharing the information with the other participants. Once the predefined threshold of KeyShares deems the block to be valid, it is added to the chain. As such, consensus can be reached even if some operators (up to the threshold) are faulty or not currently online.