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Introduction

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Ideas and Theory

Use Case

Constructions

Filecoin PoS

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Background

SNARKs Vector Commitments Depth-Robust Graphs Cost Model Merkle Trees

SNARKs and Vector Commitments in PoUS

Depth-Robust Graphs in PoUS

Security in the Cost Model

To model the security of Proof of Space, we consider a rational attacker.

The intuition is that since storage providers cannot save any costs by misbehaving, then they are likely to simply behave honestly. Therefore, a rational provider or attacker will chose the honest strategy.

In PoS case, the advantage of the adversary depends on the relation between storage costs and other resources (such as computation), and on the availability of these resources to the adversary.

An adversary will be bounded to a certain number of concurrent threads of execution. This restriction is justified by the fact that a rational adversary would only invest in extra computing resources that would incur additional costs, if such a strategy would result in lower total costs (including the underlying costs of storage).

We consider two different resources for the prover:

• computation: a CPU unit required when executing some tasks
• storage (over time): a space unit that is “reserved” for a unit of time

Storage as well as computation are directly convertible to cost.

On this page

• Background
• SNARKs and Vector Commitments in PoUS
• Depth-Robust Graphs in PoUS
• Security in the Cost Model