Skip to main content

Challenges & Plot Filters

In this lesson, we discuss how the plot filter works, and what the benefits are of using one.

Learning objectives

  • Plot Filters: Understand the basics of how the plot filter works, as well as the benefits of using one.
  • Challenge Generation: Understand how the challenge is generated by the Timelord and sent to the Farmer.



Expand for the full script

The Timelord generates a new challenge about every 9 seconds. This is then hashed with the ID of each plot.

If the hash starts with 9 zeroes, the plot is considered eligible for harvesting. This is called the plot filter. The Plot Filter serves as a decentralizing force to further randomize the winner, as well as reduce the total compute needed for each challenge.

When a farmer receives a challenge, the harvester first determines which plots are valid and pass the plot filter, then produces potential proofs of space and submits them to the Timelord for verification and review.

The Timelord will choose the Proof of Space that most closely meets the challenge, and using the challenge and provided Proof of Space as inputs, runs a VDF to prove that time has passed and produces the next challenge.

Common gotchas

  • Are valid proofs filtered out?: It is very possible that a valid proof of space would be contained in a filtered plot. This affects every farmer equally though, and the benefits of further decentralization are well worth it.

Knowledge check

Question 1 - Challenge Frequency

About how often will a Timelord generate a new challenge?

Answer (expand when ready to see the answer)

About every 9 seconds

Question 2 - Filter Benefits

What are the two significant benefits of using a plot filter?

Answer (expand when ready to see the answer)
  1. It further decentralizes the network.
  2. It reduces the amount of compute needed, improving network efficiency

Additional resources

  • More farming basics: overviews of plotting, pooling, and rewards.
  • In depth architecture overview: describing the interactions between Farmers, Harvesters, Wallets, etc.
  • Chialisp detailed documentation: detailed information on all aspects of chialisp.
  • Support in discord: for further support join our discord server and ask in the #chialisp or #support channels.