5 ms·
Sybil control mechanisms like PoW, PoS, and PoH are intended to rate-limit block producers, in order to prevent any one entity from controlling the network. In
by remolacha 5y ago
Sybil control mechanisms like PoW, PoS, and PoH are intended to rate-limit block producers, in order to prevent any one entity from controlling the network. In Bitcoin PoW, a block is produced every 10 mins, and your chance of getting to propose the next block is related to your hash power. All block producers are competing for the same slot in the blockchain.
As I understand PoH, blocks are instead continually proposed, but block producers are rate-limited by having to show completion of an operation similar to a verifiable delay function. Therefore, block producers avoid having to all compete for the same slot in the blockchain and duplicate lots of work. This is actually a novel Sybil control mechanism that is more efficient than standard PoW/PoS. It's somewhat analogous to the difference between a dedicated communication channel (as in landline phones) and a packet-switched communication channel (as in the internet).
The catch is that the PoH operation approximates a verifiable delay function, but is not currently proven to be equivalent to one. So there's the possibility of a black swan event where someone discovers a clever way to speed up the PoH operation, allowing them to cheaply control the network.
Another knock against Solana is that although it has innovated in transaction efficiency, its token distribution/crypto-economics may be less "fair" than competitor blockchains.
Please correct me if you spot any mistakes.
- SheinhardtWigCo 5y ago> This is actually a novel Sybil control mechanism that is more efficient than standard PoW/PoS. It's not novel, it's PoW with a different name. The "verifiable delay function" is hashing, which you can speed up by using faster GPUs or ASICs. Doesn't that sound familiar?
- nivertech 5y agoNo, PoW can be parallelized, but VDF/PoET cannot, that's why it's also called PoSW. PoW (Proofs of Work) PoSW (Proofs of Sequential Work) VDF (Verifiable Delay Function) PoET (Proof of Elapsed Time)
- keymone 5y agoWhy can’t it be parallelized?
- nivertech 5y agoBecause each computation needs an output of the previous iteration, so the only way to beat other miners/validators/block providers/etc. is to have a better single thread performance, basically you need to build a faster CPU. PoET (Proof of Elapsed Time) works differently, there you basically running a sleep or a timer inside an Intel SGX secure enclave, so you have to trust Intel, and also need to hope that there are no security vulnerabilities there.
- keymone 5y agoOk, I have best single thread performance on my validator machine. What if I have two of those machines?
- nivertech 5y agoOne of them will finish calculating VDF earlier, and that result will be verified by other nodes. When used for leader selection, VDF’s offer a substantial improvement over verifiable random functions. Instead of requiring a non-colluding honest majority, VDF-based leader selection only requires the presence of any honest participant. This added robustness is due to the fact that no amount of parallelism will speed up the VDF, and any non-malicious actor can easily verify anyone else’s claimed VDF output is accurate. [1] [1] https://blog.trailofbits.com/2018/10/12/introduction-to-verifiable-delay-functions-vdfs/ https://blog.trailofbits.com/2018/10/12/introduction-to-veri...
- keymone 5y ago> One of them will finish calculating VDF earlier how is that different from one miner finding a valid signature faster than the other? and how is that not parallelization?
- rowaweigh 5y agoHow do you achieve consensus if blocks are continually being produced?