Solana Blockchain

Solana Blockchain proposes a new blockchain architecture based on Proof of History (PoH) - a proof for verifying order and passage of time between events. PoH is used to encode trustless passage of time into a ledger - an append-only data structure. When used alongside a consensus algorithm such as Proof of Work (PoW) or Proof of Stake (PoS), PoH can reduce messaging overhead in a Byzantine Fault Tolerant replicated state machine, resulting in sub-second finality times. This paper also proposes two algorithms that leverage the time-keeping properties of the PoH ledger - a PoS algorithm that can recover from partitions of any size and an efficient streaming Proof of Replication (PoRep). The combination of PoRep and PoH provides a defense against forgery of the ledger with respect to time (ordering) and storage. The protocol is analyzed on a 1 Gbps network, and this paper shows that throughput of up to 710k transactions per second is possible with today's hardware.

Proof of History (PoH)

Proof of History is a sequence of computations that can provide a way to cryptographically verify the passage of time between two events. It uses a cryptographically secure function written so that output cannot be predicted from the input, and must be completely executed to generate the output. The function is run in a sequence on a single core, its previous output as the current input, periodically recording the current output, and how many times its been called. The output can then be re-computed and verified by external computers in parallel by checking each sequence segment on a separate core. Data can be timestamped into this sequence by appending the data (or a hash of some data) into the state of the function. The recording of the state, index, and data as it was appended into the sequences provides a timestamp that can guarantee that the data was created sometime before the next hash was generated in the sequence. This design also supports horizontal scaling as multiple generators can synchronize amongst each other by mixing their state into each other's sequences. Horizontal scaling is discussed in depth in Section.