This conversation is taken from an interview with Ahsan Ali Khalid from Block Publisher which you can find here…

JL777: PoW changes the consensus rules so that blocks that are notarized cannot be overwritten. Additionally, we change the “confirmations” to return 1, until it is notarized so exchanges that wait for 2 or more confirmations, are waiting for notarization and once notarized it can't be undone.

Ahsanalikhalid: So even if the chain is hacked, its block remain unalterable?

JL777: Actually it seems the chain is very hard to hack only the blocks that are not notarized yet are at risk and if you wait for more than 1 confirmation to be reported, then you know it is safe. This is cross-written to the BTC chain so there is a secure external reference.

Ahsanalikhalid: Bitcoin level security is provided in the Komodo ecosystem owing to the backup right?

Jl777: it is really a rather simple change as it only needs one change to the consensus rule, yes, dPoW is used by all the non-test chains in the ecosystem.

Ahsanalikhalid: Right! Last quest, how big do you think is the issue of 51% attack for PoW employing chains?

JLl777: Most pure PoW chains that don't any other protections are basically totally vulnerable, the only exceptions are the chains that have the most hashrate for a specific algo AND there isn't a majority of that hashrate available via nicehash. PoW works great if you have the massive hashrate, like bitcoin. You just know that there just isn't enough hashrate in the world to conduct a successful attack. But if you look at nicehash and the available hashrate across all the different algorithms, you can quickly see how many coins are vulnerable. even many of the top coins as the cost of conducting attack compared against the daily liquidity, it is often a very big ratio

Ahsanalikhalid: Just to clarify, who does the notarization as you stated above?

JL777: All nodes in the network validate all the proposed notarizations, that makes it decentralized. There are 64 special nodes that are elected each year that wait to get consensus between themselves as to what the blockhash was at a certain height they then broadcast this tx and all the nodes in the network check to see if it matches what they already have. if so, it becomes the notarized height. if not, it is ignored. so the notarization only acts as reinforcing what is already there. it can’t change the block, it certainly doesn't make the block, it just broadcasts what the notary nodes came to consensus on by acting as normal nodes.

Ahsanalikhalid: Got it! So essentially there are two layers of confirmations and once both are passed, blocks are sealed permanently, right?

JL777: Yes! the normal consensus is done, normally, and whatever that consensus says the blockhash was for 10 blocks ago, that gets notarized if the notaries agree on it. So, if there is no notarization, that is actually a signal that something might be going on with the network. this external source of data allows to gain the security. and to minimize the impact on the consensus mechanism and to reduce the power of the notaries, all a notarization does is act as a permanent confirm to a node, but only if it is already there so basically a node is 10 blocks deep and a notarization comes in that agrees with it. At that point the node will reject any attempt to change that block. it is important that there is a delay that delay allows the network to reach normal consensus

Ahsanalikhalid: Nice, great explanation….