“51% attack” is meaningless if you can’t find a way to profit on it. It costs money to run an orphan chain that long. You can’t simply double-spend because you are the biggest miner so long as everyone is running software that prevents it. To profit you must find a way to earn money with transactions on a given chain that are then wiped out when you release the longer chain.

The typical way to profit from this is to deposit to a centralized exchange, trade it for something else, and withdraw before the exchange recognizes what’s happening. However there are simple calculations you can make with the cost of 51% hashing and then the exchange can bump up the minimum confirmations required for deposits and limit the amount you can deposit for weaker currencies.

In general the 51% problem is no longer easy to profit from except with low quality exchanges.

I think the attack looks like, two transactions at the same time, one sending to exchange or merchant, one sending elsewhere (back to owner). Keep orphan chain open long enough for merchant to send goods or exchange to payout. Then release orphan chain and have it "snap back" to a world in which you received something but didn't have to pay for it.

https://unhashed.com/cryptocurrency-news/five-successful-51-...

It's quite hard to find a merchant that accepts a cryptocurrency so unpopular, that a 51% attack on it is relatively cheap. And any exchange that really cares about the security of its funds has very long confirmation times for such cryptoassets and/or monitors those chains for any suspicious activity so that the withdrawals can be frozen if anything happens.

Not saying it's impossible to do a successful 51% attack, just that it's a lot less trivial than it might seem after checking out a site like https://www.crypto51.app/

this site only indicates how much it will cost per hour to sustain the attack. it is unknown how long it could really take for attack to be successful, also as others pointed out - there's no incentive But yes, most of these garbage tokens can be attacked. But it is quite evident to me that eventually people will understand that it is just Bitcoin that they need to follow to keep up to date with the field of cryptocurrencies. Others claim to bring cool concepts and technology but in actuality they don't work or are a messed up very large software project like Ethereum (and tons of projects don't are simply forks with no further development)

And if you don't want to bother doing the math, go to https://www.crypto51.app/

How many of the coins in this list are heavily premined, and the high marketcap/attack-price ratio is only related to the big amount of coins hold by the creators?

Is it possibly to see other indicators like daily volume? (that can also be manipulated ...)

Interesting site. Only thing I would change would be to find the attack cost based on block time. Ethereum has a block time of 15 seconds whereas Bitcoin has a block time of 10 minutes. This changes the amount of damage that can be done in a given amount of time.

I welcome pull requests [0]! :)

[0] https://github.com/tdickman/crypto51

Nice! I didn't realize you were on HN, I've sent your site to friends before. I'm curious -- has your traffic increased or decreased lately (due to the bust)? Do you track your traffic or graph it at all?

I track it via Google Analytics -> here's a screenshot of the last few months [0]. Traffic has been pretty steady over time with a few spikes from Hacker News or Twitter mentions. I believe the most recent spike in traffic is related to the 51% attack against Vertcoin [1].

[0] https://i.imgur.com/UwFrpgs.png

[1] https://bitcoinist.com/vertcoin-vtc-51-attack-100k-double-sp...

How come they don't list Monero (XMR)?

Oops - good catch. Monero moved to a new mining algorithm (cryptonightv8), and crypto51 was using an old hardcoded list of NiceHash supported algorithms. I just updated the site to use the NiceHash API to keep this list up to date [0].

[0] https://github.com/tdickman/crypto51/commit/d55f3f33319f8afa...

State actors would find it very feasible with Bitcoin, too, if they decided it was in their mutual interest.

ASIC production for Bitcoin mining exists only with the implicit consent of the governments of the handful of countries that contain fabs capable of leading edge nodes.

It would not be difficult for these governments to secure a monopoly on ASIC production, and at trivial cost launch a permanent attack on the network.

It’s much easier than that, all the bitcoin hashpower is in the PRC, all it would take to initiate a 51% attack is for Beijing to send a strongly worded memo to the miners.

Keeping that a secret would be nigh impossible. It's still extremely unlikely this would actually work in the government's favor.

Why would they need to keep it a secret? Doing it in the open would probably be more effective.

Are you saying they couldn't at a bare minimum force Bitcoin to switch hashing functions?

No, the government could not force Bitcoin to adopt a new hashing function. It would be nearly impossible for any government to enforce a hardfork like that.

Why do you think doing this in the open would be more beneficial?

So if governments were to seize a monopoly on ASIC production for Bitcoin, the community would cede control of the hashing power to them rather than swapping to something else?

Make sure to also calculate the upside of attacking a small cryptocurrency. I suspect the upside is generally less than the cost of the attack.

brb, going to go corner the dentacoin market.

I'll be the only one with clean teeth in all the lands.