Bitcoin Forum

It would be interesting to see your arguments for either of these options.

Also what do you think of SECURE PROOF OF STAKE?

 “Secure Proof of Stake” is combining eligibility through stake and rating, random validator selection and an optimal dimension for the consensus group.

The consensus protocol starts by randomly sampling a smaller consensus group out of all eligible validators in the shard (for reduced communication) using a randomness source derived from the previous block’s signature. The randomness source is unpredictable before the signing of the previous block. The sampling is deterministic, meaning that every node can compute the list of validators in the consensus group and the first node to be selected is the block proposer.

The block proposer aggregates transactions into a new block and sends this block to the validators in the consensus group for verification. Each validator will verify the validity of the block, process the transactions and if everything checks out will participate in the pBFT consensus. The voting in the pBFT is done for every validator by sending a signature for a multisignature scheme. If the proposer collects more than 2/3 + 1 signatures from the consensus group members, the block is considered validated, the aggregated signature can be added to the block and the block disseminated in the entire shard. The next consensus group will be randomly sampled using the new signature.

I'd appreciate thoughts on this :)

IMO, proof of work is currently the only consensus mechanism that has shown to be robust and secure. Proof of stake is, in essence, a nothing-at-stake mechanism.


I haven't heard of Secure Proof of stake before. Is this random validation the new ingredient here? Should this part of the protocol help reduce manipulation, probability of forking, and bad behavior among the validators?

Part 1. Intro

The consensus protocol starts by randomly sampling a smaller consensus group out of all eligible validators in the shard (for reduced communication) using a randomness source derived from the previous block’s signature. The randomness source is unpredictable before the signing of the previous block. The sampling is deterministic, meaning that every node can compute the list of validators in the consensus group and the first node to be selected is the block proposer.

The block proposer aggregates transactions into a new block and sends this block to the validators in the consensus group for verification. Each validator will verify the validity of the block, process the transactions and if everything checks out will participate in the pBFT consensus. The voting in the pBFT is done for every validator by sending a signature for a multisignature scheme. If the proposer collects more than 2/3 + 1 signatures from the consensus group members, the block is considered validated, the aggregated signature can be added to the block and the block disseminated in the entire shard. The next consensus group will be randomly sampled using the new signature.



Part 2. (this one goes a bit more into some other stuff too but gives you a bit more of perspective / context)

Secure Proof of Stake was designed to ensure resistance to known security problems like Sybil attack, Rogue-key attack, Nothing at Stake attack and others. We are achieving this by combining the following aspects:

Randomness source
The source of randomness is composed of the last block's aggregated signature and the round?s number. Being a collective signature, each node that participates in the process alters the final signature data. Even if the block proposer can control which transactions will be included in a block, the signature cannot be influenced in a predictable way. This is because the aggregated signature is created by multiple parties.

Shard reorganization
After each epoch, a third of the nodes from each shard are redistributed uniformly and non-deterministically across the other shards, to prevent collusion. This method adds bootstrapping time for the nodes that were redistributed, but the pruning mechanism will decrease this time to a feasible amount.

Consensus group selection
After each round a new set of validators are selected using last committed block?s signature, current round and the eligible nodes list. In case of network desynchronization due to the delays in message propagation, the protocol has a recovery mechanism the same members will be chosen, based on the signature of the last block, but with a different block proposer that variates with the round r. This avoids forking and allows synchronization on last block. The small time window (round time) in which the validators group is known, minimizes the attack vectors.

Node rating
Beside stake, the node?s rating influences the chances to be selected as part of the consensus group. If the block proposer is honest and its block gets committed in the blockchain, it will have its rating increased, otherwise, it?s rating will be decreased. This way, each possible validator is incentivized to be honest, run the most up-to-date client software version, increase its service availability and thus ensuring the network functions as designed.

Shard redundancy
The nodes that were distributed in sibling shards on the tree?s lowest level keep track of each other?s blockchain data and application state. By introducing the concept of shard redundancy, when the number of nodes in the network decreases, some of the sibling shards will need to be merged. The targeted nodes will instantly initiate the process of shard merging.

Threat model
Elrond assumes a byzantine adversarial model, where at least ⅔ +1 of the eligible nodes are honest (untampered code, synchronized). The protocol permits the existence of adversaries that have stake or good rating, delay or send conflicting messages, compromise other nodes, have bugs or collude among themselves, but as long as 2/3 +1 of the nodes eligible validators in a shard are honest/not compromised, the protocol can achieve consensus.

The protocol assumes highly adaptive adversaries, which however cannot adapt faster than a round?s timeframe. The computational power of an adversary is bounded, therefore the cryptographic assumptions granted by the security level of the chosen primitives hold firmly within the complexity class of problems solvable by a Turing machine in polynomial time.
The network of honest nodes is assumed to form a well connected graph and the propagation of their messages is done in a bounded time ∆.

Attack vectors prevention
1) Sybil attacks: mitigated through the stake locking when joining the network. This way the generation of new identities has a cost equal to the minimum stake;

2) Nothing at stake: removed through the need of multiple signatures, not just the proposer one, and the stake slashing, if a consensus group tries to append blocks on different forks. The reward per block compared to the stake locked will discourage such behavior;

3) Long range attacks: mitigated by our pruning mechanism and the use of a randomly selected consensus group every round (and not just a single proposer);

4) DDoS attacks: the consensus group is randomly sampled every round (few seconds) so a time to DDoS is almost impossible. We are implementing a built-in filtering mechanism for duplicate or malicious messages.

Other attack vectors we have taken into consideration are: single shard takeover attack, transaction censorship, double spend, bribery attacks, etc.

Through research i will choose POW over POS because pow is just plain successful ,its secure and robust through mining the coin tends to grow faster too and have hash increasing ,for pos you'd be a rich fellow to earn from it as it requires massive setup to run

Every coin has its own needs, you can't force all coins to be one or the other, some will profit from being PoW and some will profit from being PoS. For example if you turn bitcoin into PoS it will probably have worse outcomes than staying as PoW so you can't really change it to a PoS system without killing the market. You will destroy all the bitcoin miners that spent millions upon millions of dollars for bitcoin and all those machines will become worthless.

Moreover, if you turn ethereum into PoS system which they are right now there are still a lot of coins that people can mine with their GPU hence you will destroy nothing. That is why which one is the best is a subjective question, it all depends the type of coin we are talking about. Some coins are neither of those and use the proof of stealh to keep it a low profile, some use other stuff basically all of them are selecting which one is best for them.

I was originally a fan of pow because it was kind of a genuine work and reward was generated for the work done while pos is close to other sketchy models as well that is why i was not a big fan but now due to large energy consumotion, negative effect on ecosystem and environment and last but not the least expensive equipment im giving up support for pow algorithm, i think we need a simple and more efficient system.

POW is actually a more efficient and logical work system. But energy consumption forces us to think differently. Until this energy problem is solved, POS seems to be the best.

I agree that we can't just completely ignore energy consumption - what do you think of Secure proof of stake?

PoW is best short-term because it has been shown to work. However it is energy-intensive and not really sustainable indefinitely, so PoS - either pure PoS or else some hybrid or modified system - is the way to go in the long-term.

Of course POS is the best and we can earn easy rewards from Proof of stake... it has high security and  100% transparency...  
In POS there is no need of super computer and high speed internet to do staking...

I think both of them are good, because each has advantages and disadvantages, and if combined both of them are far better, now we can see some coins made through pow and made by post, both of which have advantages and disadvantages.

I think even POS has its limitations - thus we've worked on that and created Secure Proof of Stake :)

I think PoW is still much OK than PoS which really do reward for every node create in the blockchain but pos is base on the number of what you stake and the reward is fixed to the stakes and will stay with Pow as it is a way much advance to improve the technology .

There is no absolute system. PoW has its advantages and disadvantages, just as PoS has. The unfortunate thing is that both cannot be combined in the same project, at least for now so that we can get the advantages synchronized.

Ethereum 2.0 tries to combine the two - there is an interesting article on this that tackles these issues. Let me know if you want a link to it :)

IMO, POS is a very fragile consensus unlike a very strong POW. we can see coins that have a POS system are very easily destroyed if the market starts to fall. because people prefer to dump their coins into the market rather than keep hold.

I think that the POW is an outdated model. POS will help technology move much faster. I think that Vitalik chose the transition to this mechanism for a good reason

But is it viable tho?

To me, people always start about how bad PoW is by stating that it is totally an expensive way to secure the network, that it is power hungry and makes the environment bad. Fair points, if POW was nothing but mining but in the case of the biggest POW coin of all, Bitcoin, it provides so much more than that, namely first and foremost, security of the entire network.

POS I think can never be as secure because there is so little attraction for the latter owners, everybody thinks they can earn by staking. So did I! I bought so many POS coins and thought I was being smart by earning from nothing but even during the bull run, their price just kept getting lower and lower and interest from staking just never caught up.

I think serious miners will only do POW. And serious coins won't trust POS. That's just my feeling.

Did you check the Secure Proof of Stake principle? - Give us a shout about your thoughts on that :)

I think PoW is ok, but the problem is machines are so expensive and you don't get anything from them and also power consumption is very high with bitcoin mining machines than others... Can't they develop better bitcoin machines? Or is bitcoin mined so much now, you can't get anywhere if you don't invest big? Because I think mining bitcoin now is a lot of work...

https://www.asicminervalue.com/

There are currencyes that uses both PoW and POS, but I think currency should use only one. By my opinion both are great, you don't get anything without work, much better than XRP.

Casper POS is not removing PoW system but it makes or gives the possibility to the stake holders to get the benefit from the blockchain. That's why the core developer of ethereum has called that as a hybrid system.

This depends on coin price and also how much will cost to get the coin via PoS and how much is the price of coin and if total price is higher than cost to produce is ok, but for some coins is better to have PoS, less cost to produce and if price is ok, a good profit.

In my opinion is this, I know both of these ways are used in order to support the blockchain or to create a coin but I think PoS is much better rather than the PoW since PoW needs a lot of investment and when the coins you're mining are dropping its price you're paying more in your equipment and electricity rather on what you're mining and it consumes a lot of electricity which can be used to do other good things isn't?

While the PoS uses stakes in order to earn through masternode if i'm not mistaken this kind of method is much better rather than the PoW. All of these is just according to my experience and understanding about the PoW and PoS.

I would say both of traditional POW and POS systems have failed.
Though some of the most successful coins like Bitcoin, Ethereum and Monero are purely POW (upto this date), POW are a burden to already limited energy sources in the world. POS on the other hand is a complete failure though some coins have succeeded implementing a different modification of it.

What's your thoughts on Secure Proof of Stake?

Seems like Proof of work is the best to make use of. I don’t really understand this proof of stake you’re talking about, maybe you should just make this in a way it’s easy to understand or just explain further. But in my opinion, I still believe that PoW is the best cause it has proven to be secure.

In my opinion, POW is better than POW because it will reduce power consumption and contribute to protect environment, and it avoids the situation of centralization of big mining coin companies

I believe you meant PoS is better than PoW?  :)

It's right, but POS less decentralized compared to the POS system. The global warming must force us move to the conservative system that called POS.
But it can be manipulated consider how much the power depends on how much your stake holders.

Did you check the Secure proof of stake?