<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>betwixthewires</author><text>This attack &lt;i&gt;has&lt;/i&gt; happened, at least twice to ETC and many others.&lt;p&gt;Proof of work networks with the same hash algorithm are a threat to one another, particularly, if a network exists that is profitable enough to have exorbitant resources dedicated to mining, those resources are available to attack a much smaller network if that becomes more profitable for some period than just continuing to mine the bigger one.&lt;p&gt;Proof of work then only protects the largest projects using unique hash algorithms.</text><parent_chain><item><author>barbegal</author><text>Proof of work has always had an economic flaw that you could theoretically temporarily rent enough mining power to perform double spends of more value than the cost of renting those devices.&lt;p&gt;But this attack has never been performed because the reality of all these cryptocurrencies is that the security depends only relatively weakly on proof of work. Instead it relies on trust between the main stakeholders: miners, big nodes and developers. This is just like any other human organisation. That trust is only reinforced by proof of work, making it easier for new parties to become trusted.</text></item></parent_chain></comment><story><title>Proof of stake is incapable of producing a consensus</title><url>https://yanmaani.github.io/proof-of-stake-is-a-scam-and-the-people-promoting-it-are-scammers/</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>crazypython</author><text>&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.crypto51.app&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.crypto51.app&amp;#x2F;&lt;/a&gt;&lt;p&gt;To execute a double spend, you the one sending the transaction and the miner must coordinate.&lt;p&gt;For large transactions, it is recommended to wait for six confirmations. (six blocks that agree with the transaction and have not been 51%ed.)&lt;p&gt;The 1 hour 51% cost of Bitcoin is 1.9m$. However, you would need much more time than that to find six consecutive blocks alone, without the help of the network. So, while the network is 6 blocks ahead, you need to find 7 blocks. The network moves forward a block, you must move forward more than one block to catch up. This could take a long time, and longer the more confirmations required- each confirmation makes each previous transaction exponentially more secure. Simply controlling the mining power momentarily only puts recent transactions vulnerable.&lt;p&gt;However, that much hardware is available for rent-see “Nicehashable.”</text><parent_chain><item><author>barbegal</author><text>Proof of work has always had an economic flaw that you could theoretically temporarily rent enough mining power to perform double spends of more value than the cost of renting those devices.&lt;p&gt;But this attack has never been performed because the reality of all these cryptocurrencies is that the security depends only relatively weakly on proof of work. Instead it relies on trust between the main stakeholders: miners, big nodes and developers. This is just like any other human organisation. That trust is only reinforced by proof of work, making it easier for new parties to become trusted.</text></item></parent_chain></comment><story><title>Proof of stake is incapable of producing a consensus</title><url>https://yanmaani.github.io/proof-of-stake-is-a-scam-and-the-people-promoting-it-are-scammers/</url></story>