dagger-research/evaluations/filecoin.md

An evaluation of the Filecoin whitepaper

2020-12-08 Mark Spanbroek

https://filecoin.io/filecoin.pdf

Goal of this evaluation is to find things to adopt or avoid while designing Dagger. It is not meant to be a criticism of Filecoin.

Pros:

• Clients do not need to actively monitor hosts. Once a deal has been agreed upon, the network checks proofs of storage.
• The network actively tries to repair storage faults by introducing new orders in the storage market. (§4.3.4).
• Integrity is achieved because files are addressed using their content hash (§4.4).
• Marketplaces are explicitly designed and specified (§5).
• Micropayments via payment channels (§5.3.1).
• Integration with other blockchain systems such as Ethereum (§7.2) are being worked on.

Cons:

• Filecoin requires its own very specific blockchain, which influences a lot of its design. There is tight coupling between the blockchain, storage accounting, proofs and markets.
• Proof of spacetime is much more complex than simple challenges, and only required to make the blockchain work (§3.3, §6.2)
• A miners influence is proportional to the amount of storage they're providing (§1.2), which is an incentive to become big. This could lead to the same centralization issues that plague Bitcoin.
• Incentives are geared towards making the particulars of the Filecoin design work, instead of directly aligned with users' interest. For instance, there are incentives for storage and retrieval, but it seems that a miner would be able to make money by only storing data, and never offering it for retrieval. Also, the incentive for a miner to store multiple independent copies does not mean protection against loss if they're all located on the same failing disk.
• The blockchain contains a complete allocation table of all things that are stored in the network (§4.2), which raises questions about scalability.
• Zero cash entry (such as in Swarm) doesn't seem possible.
• Consecutive micropayments are presented as a solution for the trust problems while retrieving (§5.3.1), which doesn't entirely mitigate withholding attacks.
• The addition of smart contracts (§7.1) feels like an unnecessary complication.