Mining with less GPU but more PCD

Authors: @, @, @Nicola

Main Problem: Sealing is expensive (in terms of execution, since it requires expensive hardware)

Goals

• Decrease by half the GPU utilization

Intuition: Let’s decrease the cost of sealing

• Attempt 1: Reduce the SNARK load by removing SHA
• → too difficult, requires trusted setup, requires new PoRep
• Attempt 2: Off-chain PoRep verification with external network of challenger nodes
• → too difficult, but a good idea
• Attempt 3: Explore new ways to mine without luxurious hardware (utilize lower-end hardware in a better way)
• → feasible, but seems too difficult
• Attempt 3: Let someone else seal for you (will decrease the upfront cost, but won’t reduce the cost)
• → feasible, we are looking into it 👷Off-chain sealing market design sketch
• Attempt 4: Decrease the security of PoRep (even more!) to decrease the number of challenge, to decrese GPU overhead
• → feasible, very simple to implement

High level idea:

• Decrease the PoRep security by decreasing the number of challenges, which decreases the number of SNARKs
• In order to guarantee security in the network we must increase PCD
• Having a higher PCD is an ok outcome

Pros & Cons

• Pros:
• ~90% of PoRep is SNARK generation, reducing the number of SNARKs will have a real impact.
• Cons:
• However, Snark technologies has improved of 10x during the past few years, if we believe the trend continues, then this solution might be not that useful

Formulas:

• How many challenges (hence how many SNARK proofs) do we need for bits of security? (reducing s)

https://www.wolframalpha.com/input?i=1%2Flog2(1-x)+x+from+0.039+to+0.08

• How much spacegap are we willing to give up? (by increasing x)