Quote from: kushti on May 21, 2020, 10:44:16 AM

There's a notion of non-outsourceable Proof-of-Work puzzles, and Ergo Platform cryptocurrency has Autolykos PoW algorithm which prevents pool formation ( see https://docs.ergoplatform.com/ErgoPow.pdf for details).

However, if smart contracts are powerful enough, still miners can do coalitions for most of NO-PoW schemes using collaterals , see this paper of my co-authorship https://eprint.iacr.org/2020/044 (published @ FC'20).

So please consider your scheme against smart-contract powered pools.

If the private key signature is introduced into the puzzle, in addition to the risk of losing the funds, the problem of cooperative mining still exists.

If the private key signature is not introduced in the puzzle, We believe that there are no puzzles can't be outsourced. because the puzzles required in the proof of work mechanism needs to have three conditions: Difficult to compute, easy to verify, and measurable difficulty. The puzzles that satisfies these three conditions must be outsourced.