Topic: [PSA] Attention: Security vulnerability in new alt coins! (Read 2328 times)

Nopes.. read my post again..

Hmmmm... If it's that easy then it's absolutely silly that these copy-pasta clones start at such a ridiculously low difficulty.

Again, if you have knowledge of how to set the initial difficulty higher please share it. The recent flood of clones is obviously being done by amateurs that probably won't figure this out, and yet will release their coins anyway. So do everyone a favour and educate them. Maybe they will listen.

These people are going to create copy-pasta clones anyway. If we don't educate them they will be forever without this knowledge. So I encourage you to explain how to make this modification. I am sick and tired of all these clones starting at retardedly low difficulty.


Hmmmm... If it's that easy then it's absolutely silly that these copy-pasta clones start at such a ridiculously low difficulty.

Again, if you have knowledge of how to set the initial difficulty higher please share it. The recent flood of clones is obviously being done by amateurs that probably won't figure this out, and yet will release their coins anyway. So do everyone a favour and educate them. Maybe they will listen.

Not sure if you meant copy-pasta or copy-paste, but I think copy-pasta is brilliant because it really feels like all the new alt's are just trolling us like copy-pasta on 4chan...

"Copy-pasta" clones should be the new official name for coins with nothing new to offer...

Please don't show anyone where to make the change - if someone can't figure that out, then they have no business releasing code that they have no real clue how it works

The tool u mention already exists.. it's called cgminer.. or cpuminer...

you simply start a few daemons with the -connect option. That ensures it only connects to one node (which is also yours).. then you instruct your rigs to mine on your node.. as soon as you have a height > current blockheight you disconnect one daemon and restart it without the -connect option.. Voilá..

And yacoin, yes I think this has been done..

It doesn't.

It doesn't.

Please explain how that line of code raises the starting difficulty?

What are you talking about...? At difficulty 0.25 with 350 KH/s you should find a block roughly every hour, that is hardly scraps. Coins shouldn't be made with the intention of everyone getting thousands of coins in the first few days so they can hoard them until the coin reaches an exchange and then dump their thousands of coins on the market decreasing the value of the coin instantaneously. Any coin designed to be intentionally pumped and dumped shouldn't bother being released.

Bitcoin's starting difficulty was technically higher than 0.25


that generates a starting scrypt difficulty of ~0.25, every incremental increase doubles the difficulty.

Bitcoin started with:

Please do not start at zero difficulty (0.00024414 to be precise, which is the default start difficulty of litecoin). I know you're hoping to get rich quick but here's why you should not do this: 51% attack.

All someone has to do is build a tool that will mine valid blocks using GPUs as quickly as possible without asking the network if the blocks are valid or not (except the first one). Then you periodically broadcast your attack chain to the network without caring at all about the longest chain seen by your client from the network. As long as the chain is valid this will work.

With the difficulty at the default of 0.00024414, all you need is 0.00024414 * 2^23 * 10 = 10.5 MHash/s to be able to mine 10 blocks per second (the equation is difficulty * 2^32 * blocks_per_second = hashrate_required). I have noticed usually the network is only able to go 2-5 blocks per second because of network latency, and nearly everyone is getting 95%+ orphans thus wasting their hashing power. So at 10 blocks per second an attacker would have absolutely no problem mining faster than a network that's having a laggy orphan-fest. And 10.5 MHash/s is cheap... quite a lot of people have that or more. You might even be able to pull off this attack with just 5 MHash/s as long as you can build your chain faster than the legit network can.

If your new or upcoming coin uses scrypt the above tool will be able to attack your coin! I don't even think there's any need for the tool to be modified for new coins in order to work, it just needs to grab your genesis block and then go nuts producing blocks as fast as it can, periodically broadcasting its chain to ensure if you use checkpoints there's a high chance you'll checkpoint the chain it's produced. It might need some tweaking knobs for commonly changed parameters like the difficulty retarget period, number of coins per block, etc. It's also quite possible this tool could be made by using a simple proxy wrapper around the *coind server to censor data coming in to ensure it's not aware of other chains but the attacker's chain. This ensures the attacker will be able to jump on your new coin an hijack the chain as soon as you launch.

If anyone can prove that the above tool cannot be created, I am all ears. Please quote source code or something as proof. But as far as I know I am correct and it's possible to perform this attack provided the difficulty is low enough.

TL;DR New altcoin authors, please stop using the default litecoin starting difficulty. Please use a sane value such as 0.25 or 1.0 as the starting difficulty. Otherwise a 51% attack can easily steal all your and your early adopter's coins! Checkpoints will not foil this attack!