A new PoRep protocol that optimizes storage requirements between PreCommit and ProveCommit without compromising security

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📊 Motivation

The PoRep protocol today requires SPs to store ~12x sector size of data created during the replication step until the sector is proven in the on-chain proveCommit step.

The main reasons of this inefficiency are

• Current PoRep needs onchain interaction, and for security reason 150 epochs are needed between PreCommit and proveCommit. This means that SP need to keep the 11 layers of SDR for 150 epochs in order to be able to answer proveCommit challenges
• PoRep challenges during the interactive proveCommit step are chosen from all possible nodes in the graph

Synthetic PoRep drastically reduces these space needs by reducing the set of challenges that might be chosen during the interactive proveCommit step, without compromising security.

Moreover, Synthetic PoRep would to allow for an additional 25% sealing throughput (assuming the SP keeps the same computing setup as today).

🚀 Impact on Filecoin

Why Synthetic?

Unique features of Synthetic PoRep

• ⭐️ Storage requirement between preCommit and proveCommit cut by more than 90%: from ~400GB to less than 25GB!
• ⭐️ 25% additional Sealing Throughput (with same computing setup as today)
• ⭐️ Optimization achieved without proving overhead for SPs
• ⭐️ No need of a new Trusted Setup, minor changes in Actor