Therefore, at best a cryptocurrencies with merely a hashing algorithm change are as good as an exact clone of Bitcoin and not better however since Bitcoin already exists, an exact clone of Bitcoin has no innovation or value. If the hashing algorithm is slower, as most altcoin algorithms are, it is a disadvantage because it takes more processing time to validate a block and increases the number of organic re-orgs makes it easier to double spend.
Proof Of Stake In Proof of Stakeinstead of sacrificing energy to mine a block, a user must prove they own a certain amount of the cryptocurrency to generate a block. The more stake you own, the more likely you are to generate a block. In theory, this should prevent users from creating forks because it will devalue their stake and it should save a lot of energy. Proof of Stake sounds like a good idea, but ironically, there is the “Nothing at Stake” problem.
Because mining Bitcoin is costly, it is not smart to waste your energy on a fork that won’t earn you any money, however with Proof of Stake, it is free to mine a fork. An example of a nothing at stake attack is an attacker buying lots of “old stake” from users inexpensively inexpensive to users who no longer have stake in the currency.
This can be made convenient by offering small payments to users for uploading their wallet. Eventually after accumulating enough “old stake”, the user can begin creating blocks and destroying as many or more coin days than the network was at that time.
This block generation can be repeated until it catches up to and beats the current main-chain very cheaply. There are also “stake grinding” attacks which require a trivial amount of currency. In a stake  grinding attack, the attacker has a small amount of stake and goes through the history of the blockchain and finds places where their stake wins a block. In order to consecutively win, they modify the next block header until some stake they own wins once again.
This attack requires a bit of computation, but definately isn’t impractical. Because these attacks exists, including Peercoin  and Blackcoin  proof of stake cryptocurrencies have “master” public keys that control the blockchain.
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This class of cryptocurrency is either insecure or centralized, however proof of stake based on a PoW currency is useful in some systems because gaining stake is costly, but it isn’t workable for bootstrapping distributed consensus. It is an application layer protocol and tools can be built on it like websites can be built on HTTP.
There is a class of cryptocurrencies that promise features like casino websites and exchanges and anonymity protocols to be built on top of them. When creating a new website, one doesn’t make a new protocol unless it is necessary. When creating an app such as ” DarkSend “, one doesn’t need to make a new protocol such as “Darkcoin”.
These features make the coin very desirable and one of the top ten coins in the market.
Peercoin uses SHA algorithm and Proof-of-stake and Proof-of-work systems to make the network efficient and secure. New coins can be created through regular mining or minting process where people get rewards from the coins they hold.