I Came across a blog post from coinbase that addresses a 51% attack on the ETC (ethereum classic) blockchain between 5th -7th of this month showing chain reorganizations that includes double spends of around $1.1 million dollars.
Before that about $100k of vertcoin, $18 million of bitcoin gold, etc has been stolen in similar manner from different cryptocurrencies.
I am able to understand that this is due to the vulnerabilities in PoW consensus. It has also coincided with some calls for projects to switch to PoS
Here's are my questions:
1. How secure is PoS?
2. If its so secure why are most cryptos still running on PoW?
3. Does this mean that ETH blockchain is not as secure as it is said to be?
1.
PoS is more Secure than PoW.
Look at Blackcoin, it is a very secure PoS coin and it blocks all reorgs over 500 confirms.
So anything over 500 can't be reorg no matter how many coins someone owns.
Also after staking those coins go dormant for a specific time, making sure no PoS holder can dominate a PoS indefinitely like a PoW miner can.
2.
Greedy PoW miners don't want to give up control over those coin networks,
they don't care about the coin's users only their profit in fiat from selling their PoW generated coins.
3.
ETH hashrate is ~20X the ETC hashrate, but in all PoW coins, it all depends on the collusion of 51% can dominate any PoW coin.
Higher PoW Hashrate is no guarantee, enacting a rolling checkpoint similar to blackcoin would guarantee no reorgs past the rolling checkpoint limit.