Filecoin Proof of Space

We will present an instantiation of PoS protocol in Filecoin where implementation and optimization details are omitted.

Seal Operation

Seal is an operation used on the data $D$ to create a replica. The following properties are requiered to hold for Seal:

Seal forces replicas to be physically independent copies by requiring provers to store a pseudo-random permutation of $D$ unique to their public key, such that committing to store $n$ replicas results in dedicating disk space for n independent replicas (hence n times the storage size of a replica)
Seal enforces that the generation of the replica takes substantially longer than the time expected for responding to a challenge.

PoS.SEAL

Inputs: – prover key pair $(pk_P ,sk_P)$ – prover SEAL key $pk_{SEAL}$ – data $D$ Outputs: replica $R$ , Merkle root commitment $C_R$ of $R,$ proof $π_{SEAL}$

PoS.Prove

Inputs:

– prover PoSt key $pk_{POS}$ – replica $R$ – random challenge $c$ – time parameter $t$ Outputs: a proof $π_{POS}$

PoS.Verify

Inputs:

– prover public key $pk_P$ – verifier SEAL and POS keys $vk_{SEAL}, vk_{POS}$ – hash of data $D, h_D$ – Merkle root of the replica, $C_R$ – random challenge, $c$ – tuple of proofs, $(π_{SEAL}, π_{POS})$ Outputs: bit $b$ , equals 1 if proofs are valid

How PoS currently works

ON THIS PAGE