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Bitcoin => Bitcoin Discussion => Topic started by: CoinHoarder on July 04, 2014, 09:41:46 PM



Title: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 04, 2014, 09:41:46 PM
Mike Caldwell (Casascius) proposed an idea in the ALT coin subforums last year which I feel could be revisited. It is something that could help Bitcoin and Litecoin both by protecting Bitcoin and giving Litecoin more intrinsic value at the same time. He didn't receive a lot of good feedback, but Litecoin wasn't on a 6 month downtrend at that time, so I feel they may be more apt to it nowadays. This would make Bitcoin more secure, and I propose adding another chain to protect Litecoin down the road adding 3 layers of protection from different mining hardware. As long as the 3rd, 4th, etc... coins were PoW with different hashing algorithms than the coins already in the chain, it can exponentially add protection to 51% attacks by making someone that wanted to do one have to buy/develop SHA256, Scrypt, <insert coin here since we all know ASIC proof algorithms don't really exist.. or at least if they do it is buried in the ALT subforum and it isn't general public knowledge yet.> ASICs. There is no reason why this had to be used with only ASICs, you could use coins with algorithms that can only be mined currently on GPUs/CPUs/FPGAs/Etc.

I hope you guys are open to implementing this idea, as I think it is a great one. One of the best solutions to protecting against 51% attacks that doesn't seem like it would be too hard to implement.

I will quote Mikes' post here: https://bitcointalk.org/index.php?topic=176556.0

Quote
Litecoiners: Idea to make Litecoin importance skyrocket in Bitcoin ecosystem
Today at 07:20:47 PM
 #1
Quick rant: I have always viewed Litecoin as a detraction from Bitcoin and have refused to make mass quantities of physical Litecoins as a result.  I have viewed Litecoin as nothing more than a hedge against Bitcoin seeing a 51% attack due to choice of SHA256 as an algorithm.

But:  I believe I have thought of an idea that would make Litecoin far more important and relevant in the Bitcoin/cryptocurrency ecosystem, by being as ready in wait as possible in case Bitcoin really does experience a 51% attack.

In a nutshell, I view a Bitcoin 51% attack as eventually possible, for one reason:  ASIC production efficiency scales far more than linearly with the amount of money an actor is willing to put into it; a bad actor with $1 billion to 51%-attack Bitcoin with its own custom ASICs will be far more than ten times as effective than ten bad actors with $100 million.

Anyway: here is the idea:  Add a mandatory merge-mining feature to Litecoin so that it is always "merge-mining" Bitcoins, just for pretend, in hopes that one day Bitcoin will have the option of "let's subscribe to the Litecoin chain" (as a secondary means of block validation) as a way to resolve a future 51% attack on Bitcoin's SHA256-based chain.

Here is sort of how it would work:

1. Add a new requirement to the Litecoin chain such that a valid Litecoin block must contain either a record of the most recent Bitcoin block header hash, or a repeat of the hash found in the prior Litecoin block (with a limit of repetitions).  Litecoin blocks that contain outdated Bitcoin intelligence should be disfavored by nodes capable of detecting that.  Further impose the requirement that Bitcoin block headers must be represented contiguously in the Litecoin chain - Bitcoin blocks cannot be skipped (which shouldn't be a problem, when Litecoin blocks happen 4x as often as Bitcoin)
2. In the event there is an active Bitcoin block chain fork, the requirement is loosened such that the Bitcoin block header hash requirement can be satisfied by any leg of the chain, not just the one Bitcoin considers valid.
3. Add a feature to Litecoin clients that allow Litecoin users to decide to prefer or not-prefer branches of a Bitcoin fork while one is in progress.  The default for this should always favor the Bitcoin leg with the most longevity, and should disfavor long chains that suddenly appear to replace a large amount of the known Bitcoin block chain.  The user/miner/pool-op should always have an easy way to have the final say, such as by pasting in a preformatted message either exiling or checkpointing Bitcoin blocks.

Anticipated benefits:

1. Bitcoin users would have a ready made remedy to a 51% attack that they can switch to:  Bitcoin users can simply add the requirement that if a Bitcoin block header hash makes it into the Litecoin chain, that its proof of work should be given a bonus.  Litecoin community could create and maintain pulls to the Satoshi client that cause it to subscribe to the Litecoin chain and incorporate it as intelligence toward block validation and resolving block chain forks.
2.  Bitcoin would have an easy way to add an emergency upper bound to block creation, just in case an enormous amount of power suddenly appeared.  By turning on an optional must-appear-in-Litecoin requirement, the Bitcoin community could switch on an upper bound of 1 block per 2.5 minutes if it was deemed necessary.
3. Litecoin would be seen as far more important than a wannabe bitcoin knockoff without added value by those who see it that way.
4. Bitcoin's blockchain would be re-democratized to CPU/GPU users without forcing the Bitcoin community to switch to scrypt, they'd have more decentralized influence on bitcoin than those with the means to buy/make ASICs
5. The legitimacy of Litecoins would increase greatly - people would see the value of Litecoins in their role of protecting Bitcoin, and would potentially vote for the longevity of Litecoin by offering to accept LTC for goods and services, thereby increasing their value.
6. I'd start making Casascius Litecoins if you guys did this and did it well.

I'd call the concept "marriage-mining".  By doing something like this, LTC gives a nod to BTC's importance while adding synergistic value to BTC that LTC can benefit from by association.

I have brought it up in the Litecoin forums here: https://bitcointalk.org/index.php?topic=176556.0

I am interested to hear Bitcoiners opinions about it as well. I initially didn't like the idea, but towards the end of the thread on Bitcointalk I realized it could be a very good thing for BOTH Bitcoin and Litecoin. I've been really hard on Litecoin lately trying to get them to up their game, I am hopeful that if the Bitcoin community wanted this 51% protection that they would be willing to make it happen.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: DooMAD on July 04, 2014, 10:49:32 PM
Judging by the previous thread, the main concern raised was that Litecoin didn't get any perceived benefit from it.  Although at this point, with the way it's performing on the market at the moment, I suppose it could do with a bit of shaking up.  Might give it the jump-start it needs.

Would there be much impact on the size of the blockchain if this were to go ahead?  I'm not a miner, so I can't really imagine what other potential drawbacks the idea might have.

Also, it's amusing the difference a year makes.  People in that thread were saying "Litecoin is going to get loads of publicity when it goes on gox", heh.  I guess they're pretty thankful now that it didn't.   :D


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: Mats8500 on July 05, 2014, 12:06:03 AM
I actually think it benefits both.

It would make bitcoin more secure.

It would give more value to Litecoin.

Eventually, the concept could be expanded as well as mentionned.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: darkota on July 05, 2014, 12:10:41 AM
This is a very stupid idea to be completely honest.

Litecoin is even more vulnerable to 51% attacks than Bitcoin. It's difficulty is Way lower, and if you guys haven't noticed, there are Scrypt ASIC. Meaning that the same issues 51% problem for Bitcoin, is also there for Litecoin and it's much easier to successfully 51% attack Litecoin than Bitcoin .

Litecoin is not the silver to anyone's gold, it's simply just another shit alt-coin...with not much of a community(Yes i have an account at litecointalk and there is Hardly any activity there), and absolutely no new features or innovation. Nothing, Nada, zip. Litecoin can be compared to Dogecoin in the lack of innovation and any new features and the constant downfall in price, but even Dogecoin has a robust, outstanding community, while Litecoin's community is more empty than the Saharan Desert.
 
What you need, is a coin that won't suffer as much from the same 51% attacks that threaten Bitcoin.

Litecoin is definitely not the answer, there's nothing special about it, it's on a decline to 1 satoshi, has no community, and it's 10000000x easier to 51% attack than Bitcoin....


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: callumcoutts on July 05, 2014, 02:14:20 AM
This is a very stupid idea to be completely honest.

Litecoin is even more vulnerable to 51% attacks than Bitcoin. It's difficulty is Way lower, and if you guys haven't noticed, there are Scrypt ASIC. Meaning that the same issues 51% problem for Bitcoin, is also there for Litecoin and it's much easier to successfully 51% attack Litecoin than Bitcoin .

Litecoin is not the silver to anyone's gold, it's simply just another shit alt-coin...with not much of a community(Yes i have an account at litecointalk and there is Hardly any activity there), and absolutely no new features or innovation. Nothing, Nada, zip. Litecoin can be compared to Dogecoin in the lack of innovation and any new features and the constant downfall in price, but even Dogecoin has a robust, outstanding community, while Litecoin's community is more empty than the Saharan Desert.
 
What you need, is a coin that won't suffer as much from the same 51% attacks that threaten Bitcoin.

Litecoin is definitely not the answer, there's nothing special about it, it's on a decline to 1 satoshi, has no community, and it's 10000000x easier to 51% attack than Bitcoin....
meh, use the myriadcoin codebase merged with the codebase from twister and the codebase from namecoin then, and then do the op.



Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: BittBurger on July 05, 2014, 02:39:37 AM
Can we make Litecoin a "treechain" of Bitcoin?


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: LiteCoinGuy on July 05, 2014, 08:46:09 AM
its always good to have some Litecoin beside of bitcoin. people say : "oh litecoin value goes down"...you know what? every other alts has gone down also but with 90% or more (feathershit, dogeshit).

Litecoin is still the silver of the cryptoworld and the second best alt out there.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: BanksWorstFear on July 05, 2014, 09:02:52 AM
I thought of the idea when the 51% gigahash issue came up most recently. Apparently not that many else did as litecoin's price didn't swing up to any noticeable effect.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 05, 2014, 05:32:09 PM
The crypto world would be a better place if we worked together. It is odd that both sides here (Bitcoin and Litecoin) are not interested in working together to do this.

I found it pretty disturbing most people in the Litecoin community didn't want to do it. I guess it's gonna take a $0.50 Litecoin before they will do anything. One of their biggest slogans right now is "we help with Bitcoin development", but IMO if they truly wanted to help Bitcoin then they would be more open to implementing this.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: darkota on July 05, 2014, 05:38:02 PM
The crypto world would be a better place if we worked together. It is odd that both sides here (Bitcoin and Litecoin) are not interested in working together to do this.

I found it pretty disturbing most people in the Litecoin community didn't want to do it. I guess it's gonna take a $0.50 Litecoin before they will do anything. One of their biggest slogans right now is "we help with Bitcoin development", but IMO if they truly wanted to help Bitcoin then they would be more open to implementing this.

Dude, Litecoin is already freaking dead.

It has had no updates/features/anything added by it's developer

It has an extreme lack of community, Dogecoin's puts it to shame

It has no first mover status

It has no adoption by any major organizations/companies at all


Leave that dead coin alone please. No one wants to affiliate a shit alt-coin like Litecoin, with Bitcoin.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 05, 2014, 06:01:30 PM
The crypto world would be a better place if we worked together. It is odd that both sides here (Bitcoin and Litecoin) are not interested in working together to do this.

I found it pretty disturbing most people in the Litecoin community didn't want to do it. I guess it's gonna take a $0.50 Litecoin before they will do anything. One of their biggest slogans right now is "we help with Bitcoin development", but IMO if they truly wanted to help Bitcoin then they would be more open to implementing this.

Dude, Litecoin is already freaking dead.

It has had no updates/features/anything added by it's developer

It has an extreme lack of community, Dogecoin's puts it to shame

It has no first mover status

It has no adoption by any major organizations/companies at all


Leave that dead coin alone please. No one wants to affiliate a shit alt-coin like Litecoin, with Bitcoin.

Shut up already bro. Anyone that cares knows your opinion after you repeated it the first 500 times. This thread is about securing Bitcoin and saving Litecoin.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: fryarminer on July 05, 2014, 06:22:46 PM
I think Casascius' idea is a great one! How can it be implemented? Who do we need to convince?


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: Ron~Popeil on July 05, 2014, 06:32:52 PM
I actually think litecoin is a good compliment to bit coin. The complete lack of activity around it is somewhat mysterious to me. It will probably fall to third in market cap before the end of the year.

I think the idea could work and benefit both coins but we kind of need a peep or two from their developers to even consider it.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 05, 2014, 06:37:36 PM
I think Casascius' idea is a great one! How can it be implemented? Who do we need to convince?


The Bitcoin and Litecoin development teams would need to work together.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: EcuaMobi on July 05, 2014, 06:41:18 PM
This is a very stupid idea to be completely honest.

Litecoin is even more vulnerable to 51% attacks than Bitcoin. It's difficulty is Way lower, and if you guys haven't noticed, there are Scrypt ASIC. Meaning that the same issues 51% problem for Bitcoin, is also there for Litecoin and it's much easier to successfully 51% attack Litecoin than Bitcoin .

Litecoin is not the silver to anyone's gold, it's simply just another shit alt-coin...with not much of a community(Yes i have an account at litecointalk and there is Hardly any activity there), and absolutely no new features or innovation. Nothing, Nada, zip. Litecoin can be compared to Dogecoin in the lack of innovation and any new features and the constant downfall in price, but even Dogecoin has a robust, outstanding community, while Litecoin's community is more empty than the Saharan Desert.
 
What you need, is a coin that won't suffer as much from the same 51% attacks that threaten Bitcoin.

Litecoin is definitely not the answer, there's nothing special about it, it's on a decline to 1 satoshi, has no community, and it's 10000000x easier to 51% attack than Bitcoin....

Even if both coins can be 51% attacked, it'd be more difficult to attack both coins at the same time.
If somebody successfully attack Bitcoin, he would need to perform the same attack to Litecoin too, so it's verified. Quite difficult.

Be it Litecoin or another alt coin, I think it's a great idea.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 05, 2014, 07:01:59 PM
This is a very stupid idea to be completely honest.

Litecoin is even more vulnerable to 51% attacks than Bitcoin. It's difficulty is Way lower, and if you guys haven't noticed, there are Scrypt ASIC. Meaning that the same issues 51% problem for Bitcoin, is also there for Litecoin and it's much easier to successfully 51% attack Litecoin than Bitcoin .

Litecoin is not the silver to anyone's gold, it's simply just another shit alt-coin...with not much of a community(Yes i have an account at litecointalk and there is Hardly any activity there), and absolutely no new features or innovation. Nothing, Nada, zip. Litecoin can be compared to Dogecoin in the lack of innovation and any new features and the constant downfall in price, but even Dogecoin has a robust, outstanding community, while Litecoin's community is more empty than the Saharan Desert.
 
What you need, is a coin that won't suffer as much from the same 51% attacks that threaten Bitcoin.

Litecoin is definitely not the answer, there's nothing special about it, it's on a decline to 1 satoshi, has no community, and it's 10000000x easier to 51% attack than Bitcoin....

Even if both coins can be 51% attacked, it'd be more difficult to attack both coins at the same time.
If somebody successfully attack Bitcoin, he would need to perform the same attack to Litecoin too, so it's verified. Quite difficult.

Be it Litecoin or another alt coin, I think it's a great idea.


Yes, good explanation. If you go to the thread on the Litecoin forums, the posters are acting like they don't need this or Bitcoin. I am hoping the Litecoin developers can take a step back and look at the big picture more rationally than the posters there.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: darkota on July 05, 2014, 07:06:33 PM
This is a very stupid idea to be completely honest.

Litecoin is even more vulnerable to 51% attacks than Bitcoin. It's difficulty is Way lower, and if you guys haven't noticed, there are Scrypt ASIC. Meaning that the same issues 51% problem for Bitcoin, is also there for Litecoin and it's much easier to successfully 51% attack Litecoin than Bitcoin .

Litecoin is not the silver to anyone's gold, it's simply just another shit alt-coin...with not much of a community(Yes i have an account at litecointalk and there is Hardly any activity there), and absolutely no new features or innovation. Nothing, Nada, zip. Litecoin can be compared to Dogecoin in the lack of innovation and any new features and the constant downfall in price, but even Dogecoin has a robust, outstanding community, while Litecoin's community is more empty than the Saharan Desert.
 
What you need, is a coin that won't suffer as much from the same 51% attacks that threaten Bitcoin.

Litecoin is definitely not the answer, there's nothing special about it, it's on a decline to 1 satoshi, has no community, and it's 10000000x easier to 51% attack than Bitcoin....

Even if both coins can be 51% attacked, it'd be more difficult to attack both coins at the same time.
If somebody successfully attack Bitcoin, he would need to perform the same attack to Litecoin too, so it's verified. Quite difficult.

Be it Litecoin or another alt coin, I think it's a great idea.


Yes, good explanation. If you go to the thread on the Litecoin forums, the posters are acting like they don't need this or Bitcoin. I am hoping the Litecoin developers can take a step back and look at the big picture more rationally than the posters there.

Exactly, they don't want help. Litecoin is dead, leave it alone.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 05, 2014, 07:19:54 PM
Exactly, they don't want help. Litecoin is dead, leave it alone.

Well... I guess I agree with you here, it appears like that is true. I am hoping that the developers can see the value of the idea and convince the Litecoin sheep to follow them.

I would leave it alone, but I still have some family and friends tied up in Litecoin.. don't think they want to sell at such a loss. My friend has 5 figures tied up.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: chaoticbrain on July 05, 2014, 08:28:58 PM
Well theoretically if you had the processing power to attack bitcoin, couldn't you just attack litecoin, and change the rules around including bitcoin hashes, or whatetever, before attacking bitcoin ? 


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: ShakyhandsBTCer on July 06, 2014, 12:22:08 AM
The crypto world would be a better place if we worked together. It is odd that both sides here (Bitcoin and Litecoin) are not interested in working together to do this.

I found it pretty disturbing most people in the Litecoin community didn't want to do it. I guess it's gonna take a $0.50 Litecoin before they will do anything. One of their biggest slogans right now is "we help with Bitcoin development", but IMO if they truly wanted to help Bitcoin then they would be more open to implementing this.

Dude, Litecoin is already freaking dead.

It has had no updates/features/anything added by it's developer

It has an extreme lack of community, Dogecoin's puts it to shame

It has no first mover status

It has no adoption by any major organizations/companies at all


Leave that dead coin alone please. No one wants to affiliate a shit alt-coin like Litecoin, with Bitcoin.

Shut up already bro. Anyone that cares knows your opinion after you repeated it the first 500 times. This thread is about securing Bitcoin and saving Litecoin.
Well if the only viable use for LTC is to secure BTC then it's value would likely be near zero. If it's value is near zero then it's miners would have little incentive to continue to mine for the network.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: fryarminer on July 06, 2014, 03:28:21 AM
Well theoretically if you had the processing power to attack bitcoin, couldn't you just attack litecoin, and change the rules around including bitcoin hashes, or whatetever, before attacking bitcoin ? 

No, because SHA256 and scrypt don't use the same asic hardware, so to have 51% power in both would be near illogical, if not impossible.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: darkota on July 06, 2014, 03:32:45 AM
Well theoretically if you had the processing power to attack bitcoin, couldn't you just attack litecoin, and change the rules around including bitcoin hashes, or whatetever, before attacking bitcoin ? 

No, because SHA256 and scrypt don't use the same asic hardware, so to have 51% power in both would be near illogical, if not impossible.

That makes no sense. To get 51% of the hashrate in Litecoin is relatively Very Cheap to get 51% hashrate in Bitcoin.

Scrypt and SHA256 are very similar, I don't know what world youre living in fryarminer.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: smoothie on July 06, 2014, 07:00:56 AM
If you read the original thread when Mike penned it I was in support of his original idea presented there.

Not sure what happened and why it was not implemented.

Charlie care to remind us why?


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 07:19:58 AM
the original proposal advocates getting rid of the longest chain rule for
bitcoin in favor of some bizarre check against litecoin.

for that reason, it's mostly likely a very bad idea and not
even worthy of a core dev to comment on.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: ChuckStrawberry on July 06, 2014, 07:32:05 AM
its only time until a notable coin suffers a 51%. that will probably jump us up in adoption


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: doo on July 06, 2014, 07:55:46 AM
What exactly is the point of bringing a dead and buried discussion back up? OP must rate his life very cheaply to waste his precious time going through thousands of archival pages.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: Bitcoin Magazine on July 06, 2014, 09:05:56 AM
PPcoin is superior to Bitcoin in every shape and form.  Why not use that?


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: m3 on July 06, 2014, 09:35:32 AM
yes if one of bitcoin's pools gets close to 51% its best to move to another coin. But I think vertcoin is a better solution then litecoin because the distribution of the mining pool is more even.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 03:08:02 PM
the original proposal advocates getting rid of the longest chain rule for
bitcoin in favor of some bizarre check against litecoin.

for that reason, it's mostly likely a very bad idea and not
even worthy of a core dev to comment on.

The way I understand, it doesn't effect Bitcoin unless it is under a 51% attack and more than one chain pops up. It would be a back up to the way Bitcoin determines a valid chain, only to be used in extreme circumstances.

PPcoin is superior to Bitcoin in every shape and form.  Why not use that?
PPcoin could be used to do this, and I think alternatives should be looked into if Litecoin wouldn't want to. In fact, they seem downright hostile towards the idea so maybe it should be done on a different chain. It doesn't have to be Litecoin at all. Since Litecoin uses a different algorithm though, it would require building two different types of ASICs to 51% either network. Any coin with a different algorithm, or one secured by PoS like PPcoin would suffice.

yes if one of bitcoin's pools gets close to 51% its best to move to another coin.

If this were implemented, then it pretty much negates 51% attack unless the attacked can also gain a hold of the Litecoin network too.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 03:11:19 PM
the original proposal advocates getting rid of the longest chain rule for
bitcoin in favor of some bizarre check against litecoin.

for that reason, it's mostly likely a very bad idea and not
even worthy of a core dev to comment on.

The way I understand, it doesn't effect Bitcoin unless it is under a 51% attack and more than one chain pops up. It would be a back up to the way Bitcoin determines a valid chain, only to be used in extreme circumstances.
 

I don't think so.

It says this:

Quote
In the event there is an active Bitcoin block chain fork, the requirement is loosened such that the Bitcoin block header hash requirement can be satisfied by any leg of the chain, not just the one Bitcoin considers valid.
.

Do you see why this doesn't make any sense?  You're messing with one of the key parts of the Bitcoin system and actually making it much easier to attack.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 04:07:03 PM
the original proposal advocates getting rid of the longest chain rule for
bitcoin in favor of some bizarre check against litecoin.

for that reason, it's mostly likely a very bad idea and not
even worthy of a core dev to comment on.

The way I understand, it doesn't effect Bitcoin unless it is under a 51% attack and more than one chain pops up. It would be a back up to the way Bitcoin determines a valid chain, only to be used in extreme circumstances.
 

I don't think so.

It says this:

Quote
In the event there is an active Bitcoin block chain fork, the requirement is loosened such that the Bitcoin block header hash requirement can be satisfied by any leg of the chain, not just the one Bitcoin considers valid.
.

Do you see why this doesn't make any sense?  You're messing with one of the key parts of the Bitcoin system and actually making it much easier to attack.


No, I don't understand your point. Why specifically would it make it much easier to attack? I think it would do the opposite.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 04:11:15 PM
currently, if there is a fork, consensus is reached by using the longest chain rule.
a doublespend attack means you are secretly mining a separate chain that has to be
longer than the main chain.  to do that is very expensive requiring lots of hashing power.

this proposal says to get rid of that scheme and use a different one involving litecoin.
and litecoin requires much less hashing power.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 04:31:59 PM
currently, if there is a fork, consensus is reached by using the longest chain rule.
a doublespend attack means you are secretly mining a separate chain that has to be
longer than the main chain.  to do that is very expensive requiring lots of hashing power.

Yes I agree.

this proposal says to get rid of that scheme and use a different one involving litecoin.
and litecoin requires much less hashing power.

This I disagree with though, because someone would need to attack both the Litecoin AND Bitcoin network at the same time. Bitcoin could add in the same checks for Litecoin, so in order to attack Litecoin you'd have to attack Bitcoin too. This would increase security of both coins if implemented properly.

You do realize Litecoin has ASICs now, and the hash power has been exponentially growing for the past 6 months? It is not what I would call easy to 51% the Litecoin network at the moment. If you simply looked at the hash speed (515 Gh), it may seem like that is small compared to Bitcoin. However, you need to take into account that Scrypt is much less efficient than SHA256. You would need to develop/buy Scrypt and SHA256 ASICs to 51% attack the Bitcoin or Litecoin network, making an attack much more expensive. Therefore making it much harder to attack.

Yes, it is different from the way Bitcoin has resolved these issues in the past, but that doesn't automatically make it less secure.



Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 05:01:09 PM


This I disagree with though, because someone would need to attack both the Litecoin AND Bitcoin network at the same time. 



Yes, BUT the attack on Bitcoin would be much much cheaper if all you had to do was create a block
and your chain didn't have to be longer than the networks'. 


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 05:15:21 PM


This I disagree with though, because someone would need to attack both the Litecoin AND Bitcoin network at the same time.  



Yes, BUT the attack on Bitcoin would be much much cheaper if all you had to do was create a block
and your chain didn't have to be longer than the networks'.  

I see where you are going. This is what Mike proposed in that case:

Quote
3. Add a feature to Litecoin clients that allow Litecoin users to decide to prefer or not-prefer branches of a Bitcoin fork while one is in progress.  The default for this should always favor the Bitcoin leg with the most longevity, and should disfavor long chains that suddenly appear to replace a large amount of the known Bitcoin block chain.  The user/miner/pool-op should always have an easy way to have the final say, such as by pasting in a preformatted message either exiling or checkpointing Bitcoin blocks.

I feel like this may be able to be improved upon if a lot of people thought about it. Do you see a glaring issue in the idea? The way it was stated may not be the best way to implement it, but the idea seems like it could work.

The main chain would be quite long compared to the attacker's chain, so it seems like the client could pick up on which blocks are valid and invalid by comparing the size of the chains.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 05:22:57 PM


This I disagree with though, because someone would need to attack both the Litecoin AND Bitcoin network at the same time.  



Yes, BUT the attack on Bitcoin would be much much cheaper if all you had to do was create a block
and your chain didn't have to be longer than the networks'.  

I see where you are going. This is what Mike proposed in that case:

Quote
3. Add a feature to Litecoin clients that allow Litecoin users to decide to prefer or not-prefer branches of a Bitcoin fork while one is in progress.  The default for this should always favor the Bitcoin leg with the most longevity, and should disfavor long chains that suddenly appear to replace a large amount of the known Bitcoin block chain.  The user/miner/pool-op should always have an easy way to have the final say, such as by pasting in a preformatted message either exiling or checkpointing Bitcoin blocks.

I feel like this may be able to be improved upon if a lot of people thought about it. Do you see a glaring issue in the idea? The way it was stated may not be the best way to implement it, but the idea seems like it could work.

The main chain would be quite long compared to the attacker's chain, so it seems like the client could pick up on which blocks are valid and invalid by comparing the size of the chains.

I still don't think it would work... all you're doing in essence is relegating the consensus mechanism over to the litecoin network, which could be attacked more cheaply than Bitcoin.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 05:35:23 PM


This I disagree with though, because someone would need to attack both the Litecoin AND Bitcoin network at the same time.  



Yes, BUT the attack on Bitcoin would be much much cheaper if all you had to do was create a block
and your chain didn't have to be longer than the networks'.  

I see where you are going. This is what Mike proposed in that case:

Quote
3. Add a feature to Litecoin clients that allow Litecoin users to decide to prefer or not-prefer branches of a Bitcoin fork while one is in progress.  The default for this should always favor the Bitcoin leg with the most longevity, and should disfavor long chains that suddenly appear to replace a large amount of the known Bitcoin block chain.  The user/miner/pool-op should always have an easy way to have the final say, such as by pasting in a preformatted message either exiling or checkpointing Bitcoin blocks.

I feel like this may be able to be improved upon if a lot of people thought about it. Do you see a glaring issue in the idea? The way it was stated may not be the best way to implement it, but the idea seems like it could work.

The main chain would be quite long compared to the attacker's chain, so it seems like the client could pick up on which blocks are valid and invalid by comparing the size of the chains.

I still don't think it would work... all you're doing in essence is relegating the consensus mechanism over to the litecoin network, which could be attacked more cheaply than Bitcoin.

That's why it requires cooperation in between the Bitcoin and Litecoin development team. Bitcoin should protect Litecoin in the same way. Otherwise, you could add a 3rd coin to the chain making all coins even harder to attack.

Anyways, according to one of the most knowledgeable replies I've received thus far is that this can be done without a hard fork, and it makes it even harder to attack the Litecoin block chain in another way not mentioned in the OP:

if I remember my talks with vinced when he was implementing merge mining for namecoins, there is a unique random identifier used as input for creating new block. Vinced replaced this random number with hash for namecoins. This approach allowed creating valid merged blocks for both bitcoin and namecoin, while only namecoin had to be modified. This piece of data which was important for namecoin remained random for bitcoin as required by bitcoin specification.

Here we could use the same random piece of data, but instead of generating a random number we could use the hash of bitcoin block. From the litecoin point of view it won't be a harfork, because it will work for older litecoin clients which will view this piece of data as random number as required by litecoin specification. In fact the job of "extracting" bitcoin blockchain hashes will be a job for litecoin blockchain analysers.

So, if I'm not wrong, we can do this without a hard fork.

wow, I just realised that it would also make more difficult 51% attacks on litecoin. If someone wanted to suddenly flood the ltc blockchain with different blocks, he would need to make sure that they are in sync (time wise speaking) with bitcoin blocks.

Also, since most of litecoind modifications get merged to bitcoin, the bitcoin blockchain could similarly secure the litecoin chain using exactly the same approach. Then only a 51% attack on both blockchains simultaneously could succed. Far less likely to happen.

If my previous post is correct, then it all can be done without a hardfork!


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: QuestionAuthority on July 06, 2014, 05:36:14 PM
Bitcoin is in the process of becoming the mainstream alternative to classic banking and payments. The general public is confused enough about crypto currencies as it is and altcoins aren't helping that perception. I've never believed that crap about Litecoins silver to Bitcoins gold. That's like saying the USA needs to have Pesos and Dollars to pay for different items. That's total bullshit. Altcoins are pulling users away from adopting Bitcoin and more importantly using Bitcoin. They create an unnecessary confusion when the uninitiated look at Bitcoin. It already looks like a list of game money (WoW gold, Bitcoin, Linden, Litecoin, Zeevex, Doge). I have pumped and dumped my share of alts and made a tidy sum doing it. When Litecoin first came out I was mining Bitcoin on GPUs and Litecoin on the idle processors of a dozen computers. Alts can be money makers like a Ponzi can be a money maker.

I don't want to require the survival of any altcoin because Bitcoin is tied to it. I think if Bitcoins problems are addressed by the dev team it will be the survivor because it has a head start. All of the alts will die a slow death while Overstock and Expedia are still taking Bitcoin. There must be another solution to PoW.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 05:45:14 PM
I just want this idea to be given a fair chance without politics getting in the way. If it is indeed a good solution to 51% attacks, then I don't feel it should be brushed aside because of our feelings towards Bitcoin (in case of Litecoiners) or Litecoin (in case of Bitcoiners.)

The 51% attack problem is not really easy to solve otherwise it would have been done already. We need to be proactive and if there is a solution such as this that someone has already proposed and makes the least bit of sense, then I feel like we should give it more attention. I'm more interested in the technicalities of this, how it could be implemented, and whether or not it will require a hard fork, rather than people's opinion on Litecoin or Bitcoin.

As I said, this method could be used on a different coin other than Litecoin, but Litecoin is in my opinion the logical choice due to the stability of its network and Scrypt ASICs making it one of the strongest PoW ALT coins. It may be a good idea to add a 3rd link to the chain such as a PoS coin... the attacker would have to 51% Bitcoin and Litecoin, and then gain majority stake in the PoS coin. It should be made so that if one link in the chain breaks all the others will be fine. I think there are a lot of ways this could be implemented.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 05:46:54 PM

That's why it requires cooperation in between the Bitcoin and Litecoin development team. Bitcoin should protect Litecoin in the same way. Otherwise, you could add a 3rd coin to the chain making all coins even harder to attack.
 

It's not necessarily a question of cooperation.

The problem can be reduced to logical operators: AND vs. OR.

Do you require longest chain AND a litecoin component?
or is it longest chain OR a litecoin component.

The OR solution is clearly bad, as it throws Bitcoin
security out the window, as we just discussed.

However, the AND solution might be too constraining.
If an attacker were to just hit the litecoin network,
it could prevent consensus, causing split chains or
blocks to be unsolved.



Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: CoinHoarder on July 06, 2014, 05:53:38 PM

That's why it requires cooperation in between the Bitcoin and Litecoin development team. Bitcoin should protect Litecoin in the same way. Otherwise, you could add a 3rd coin to the chain making all coins even harder to attack.
 

It's not necessarily a question of cooperation.

The problem can be reduced to logical operators: AND vs. OR.

Do you require longest chain AND a litecoin component?
or is it longest chain OR a litecoin component.

The OR solution is clearly bad, as it throws Bitcoin
security out the window, as we just discussed.

However, the AND solution might be too constraining.
If an attacker were to just hit the litecoin network,
it could prevent consensus, causing split chains or
blocks to be unsolved.

This is why Bitcoin should protect Litecoin using the same method, that way an attacker can't just hit the Bitcoin or Litecoin network separately. They would have to hit them both at the same time. Even without this protection, Litecoin is reasonably secure. I mean.. no one has been able to 51% it yet to my knowledge. You are acting like someone could easily kill Litecoin even without this implemented (like right now), which is a bit of an exaggeration as it would take a lot of money, power, and mining equipment.

As long as pools are reaching close to 50% (recently ghash.io on Bitcoin and coinotron on Litecoin), then both Bitcoin and Litecoin are insecure to 51% attacks. They may not have malicious intent, but if the pool server is hacked the hacker may not be so nice, or someone could gain physical access to the servers (IE. a government or data center employee.) Something needs to be done about this, and I feel like the solution proposed is better than the current non-solution. People like larger pools because they produce more steady payouts, so it's a catch 22 and Bitcoin/Litecoin will constantly face these security scares until the problem is fixed on the protocol level.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: jonald_fyookball on July 06, 2014, 06:00:44 PM

That's why it requires cooperation in between the Bitcoin and Litecoin development team. Bitcoin should protect Litecoin in the same way. Otherwise, you could add a 3rd coin to the chain making all coins even harder to attack.
 

It's not necessarily a question of cooperation.

The problem can be reduced to logical operators: AND vs. OR.

Do you require longest chain AND a litecoin component?
or is it longest chain OR a litecoin component.

The OR solution is clearly bad, as it throws Bitcoin
security out the window, as we just discussed.

However, the AND solution might be too constraining.
If an attacker were to just hit the litecoin network,
it could prevent consensus, causing split chains or
blocks to be unsolved.

This is why Bitcoin should protect Litecoin using the same method, that way an attacker can't just hit the Bitcoin or Litecoin network separately. They would have to hit them both at the same time. Even without this protection, Litecoin is reasonably secure. I mean.. no one has been able to 51% it yet to my knowledge. You are acting like someone could easily kill Litecoin even without this implemented (like right now), which is a bit of an exaggeration as it would take a lot of money, power, and mining equipment.

As long as pools are reaching close to 50% (recently ghash.io on Bitcoin and coinotron on Litecoin), then both Bitcoin and Litecoin are insecure to 51% attacks. They may not have malicious intent, but if the pool server is hacked the hacker may not be so nice, or someone could gain physical access to the servers (IE. a government or data center employee.) Something needs to be done about this, and I feel like the solution proposed is better than the current non-solution. People like larger pools because they produce more steady payouts, so it's a catch 22 and Bitcoin/Litecoin will constantly face these security scares until the problem is fixed on the protocol level.

I'm not saying someone can kill litecoin easily.
I think you are missing my point.

Longest-chain-wins rule works to create consensus
in a distributed network because of its simplicity.

If you have 2 separate networks and they both
must "approve" a chain, then what happens if
one approves it and the other doesn't?





Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: QuestionAuthority on July 06, 2014, 06:00:52 PM
How are you going to protect the chosen altcoin from the Eligius pool. I not sure you will get LukeJr's support for this idea. lol


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: iluvpie60 on July 06, 2014, 08:47:19 PM
Mike Caldwell (Casascius) proposed an idea in the ALT coin subforums last year which I feel could be revisited. It is something that could help Bitcoin and Litecoin both by protecting Bitcoin and giving Litecoin more intrinsic value at the same time. He didn't receive a lot of good feedback, but Litecoin wasn't on a 6 month downtrend at that time, so I feel they may be more apt to it nowadays. This would make Bitcoin more secure, and I propose adding another chain to protect Litecoin down the road adding 3 layers of protection from different mining hardware. As long as the 3rd, 4th, etc... coins were PoW with different hashing algorithms than the coins already in the chain, it can exponentially add protection to 51% attacks by making someone that wanted to do one have to buy/develop SHA256, Scrypt, <insert coin here since we all know ASIC proof algorithms don't really exist.. or at least if they do it is buried in the ALT subforum and it isn't general public knowledge yet.> ASICs. There is no reason why this had to be used with only ASICs, you could use coins with algorithms that can only be mined currently on GPUs/CPUs/FPGAs/Etc.

I hope you guys are open to implementing this idea, as I think it is a great one. One of the best solutions to protecting against 51% attacks that doesn't seem like it would be too hard to implement.

I will quote Mikes' post here: https://bitcointalk.org/index.php?topic=176556.0

Quote
Litecoiners: Idea to make Litecoin importance skyrocket in Bitcoin ecosystem
Today at 07:20:47 PM
 #1
Quick rant: I have always viewed Litecoin as a detraction from Bitcoin and have refused to make mass quantities of physical Litecoins as a result.  I have viewed Litecoin as nothing more than a hedge against Bitcoin seeing a 51% attack due to choice of SHA256 as an algorithm.

But:  I believe I have thought of an idea that would make Litecoin far more important and relevant in the Bitcoin/cryptocurrency ecosystem, by being as ready in wait as possible in case Bitcoin really does experience a 51% attack.

In a nutshell, I view a Bitcoin 51% attack as eventually possible, for one reason:  ASIC production efficiency scales far more than linearly with the amount of money an actor is willing to put into it; a bad actor with $1 billion to 51%-attack Bitcoin with its own custom ASICs will be far more than ten times as effective than ten bad actors with $100 million.

Anyway: here is the idea:  Add a mandatory merge-mining feature to Litecoin so that it is always "merge-mining" Bitcoins, just for pretend, in hopes that one day Bitcoin will have the option of "let's subscribe to the Litecoin chain" (as a secondary means of block validation) as a way to resolve a future 51% attack on Bitcoin's SHA256-based chain.

Here is sort of how it would work:

1. Add a new requirement to the Litecoin chain such that a valid Litecoin block must contain either a record of the most recent Bitcoin block header hash, or a repeat of the hash found in the prior Litecoin block (with a limit of repetitions).  Litecoin blocks that contain outdated Bitcoin intelligence should be disfavored by nodes capable of detecting that.  Further impose the requirement that Bitcoin block headers must be represented contiguously in the Litecoin chain - Bitcoin blocks cannot be skipped (which shouldn't be a problem, when Litecoin blocks happen 4x as often as Bitcoin)
2. In the event there is an active Bitcoin block chain fork, the requirement is loosened such that the Bitcoin block header hash requirement can be satisfied by any leg of the chain, not just the one Bitcoin considers valid.
3. Add a feature to Litecoin clients that allow Litecoin users to decide to prefer or not-prefer branches of a Bitcoin fork while one is in progress.  The default for this should always favor the Bitcoin leg with the most longevity, and should disfavor long chains that suddenly appear to replace a large amount of the known Bitcoin block chain.  The user/miner/pool-op should always have an easy way to have the final say, such as by pasting in a preformatted message either exiling or checkpointing Bitcoin blocks.

Anticipated benefits:

1. Bitcoin users would have a ready made remedy to a 51% attack that they can switch to:  Bitcoin users can simply add the requirement that if a Bitcoin block header hash makes it into the Litecoin chain, that its proof of work should be given a bonus.  Litecoin community could create and maintain pulls to the Satoshi client that cause it to subscribe to the Litecoin chain and incorporate it as intelligence toward block validation and resolving block chain forks.
2.  Bitcoin would have an easy way to add an emergency upper bound to block creation, just in case an enormous amount of power suddenly appeared.  By turning on an optional must-appear-in-Litecoin requirement, the Bitcoin community could switch on an upper bound of 1 block per 2.5 minutes if it was deemed necessary.
3. Litecoin would be seen as far more important than a wannabe bitcoin knockoff without added value by those who see it that way.
4. Bitcoin's blockchain would be re-democratized to CPU/GPU users without forcing the Bitcoin community to switch to scrypt, they'd have more decentralized influence on bitcoin than those with the means to buy/make ASICs
5. The legitimacy of Litecoins would increase greatly - people would see the value of Litecoins in their role of protecting Bitcoin, and would potentially vote for the longevity of Litecoin by offering to accept LTC for goods and services, thereby increasing their value.
6. I'd start making Casascius Litecoins if you guys did this and did it well.

I'd call the concept "marriage-mining".  By doing something like this, LTC gives a nod to BTC's importance while adding synergistic value to BTC that LTC can benefit from by association.

I have brought it up in the Litecoin forums here: https://bitcointalk.org/index.php?topic=176556.0

I am interested to hear Bitcoiners opinions about it as well. I initially didn't like the idea, but towards the end of the thread on Bitcointalk I realized it could be a very good thing for BOTH Bitcoin and Litecoin. I've been really hard on Litecoin lately trying to get them to up their game, I am hopeful that if the Bitcoin community wanted this 51% protection that they would be willing to make it happen.

Won't happen. This isn't the place to do this. Basically, all ideas on here are not ideas that are incorporated into any changes towards BTC. This whole forum really is seeming pretty pointless more and more. I have no idea how there are people on here that have accounts that are years old. There is nothing to talk about, its always the same, scams, hacks, loss, gain, loss, gain, loss, opinions, and no one does anything about anything.

Bitcoin community has been broken for a long time and this "free market" you think you have is a joke, its all manipulated by bad actors in exchanges.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: ElectricMucus on July 07, 2014, 01:09:18 AM
Won't happen. This isn't the place to do this. Basically, all ideas on here are not ideas that are incorporated into any changes towards BTC. This whole forum really is seeming pretty pointless more and more. I have no idea how there are people on here that have accounts that are years old. There is nothing to talk about, its always the same, scams, hacks, loss, gain, loss, gain, loss, opinions, and no one does anything about anything.

Bitcoin community has been broken for a long time and this "free market" you think you have is a joke, its all manipulated by bad actors in exchanges.

Straight on, this would be a good idea but it isn't gonna happen because of the things you mentioned.


I'm still here because the scams, hacks, loss, gain, loss, gain, loss, opinions are very entertaining to watch and laugh at. I've gone from thinking Bitcoin as a pretty cool idea to one of the dumbest shit on the Internet.


Title: What about this...
Post by: jonald_fyookball on July 07, 2014, 01:55:13 AM
I have an idea how this could possibly work.

You create an altcoin that has a kind of merge mining with Bitcoin.
In order to solve the altcoin's blocks, you would have to solve
the most recent block on the Bitcoin blockchain, albeit at a lower difficulty
level, PLUS a block on the alt chain.

By doing this, you would force mining power to be used on the Bitcoin
blockchain.  Sometimes, you would actually solve a Bitcoin block,
but overall you would be contributing hashing power to the Bitcoin
network, while participating in a secondary market (the altcoin).

Has this been tried before?




Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: coblee on July 07, 2014, 03:15:36 AM
The reason why this idea did not take off originally was because people think that there was zero benefit to Litecoin and possibly no benefit to Bitcoin either. To do this, Litecoin miners have to maintain both the Litecoin blockchain and the Bitcoin blockchain. It will also require a hard fork on Litecoin for this to work. It's basically Litecoin holding on to a lifevest for Bitcoin in the rare case that Bitcoin will need it and use it.

It's an interesting idea. I will spend some time to think about it more and see if doing this without a hard fork is possible. You basically have to somehow create incentives for Litecoin miners to also keep track of the Bitcoin blockchain. It may be as simple as checking a few bitcoin block explorers, but why would miners want to do that for no benefit... unless they are forced to by a hard fork.


Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: smoothie on July 07, 2014, 07:03:08 AM
The reason why this idea did not take off originally was because people think that there was zero benefit to Litecoin and possibly no benefit to Bitcoin either. To do this, Litecoin miners have to maintain both the Litecoin blockchain and the Bitcoin blockchain. It will also require a hard fork on Litecoin for this to work. It's basically Litecoin holding on to a lifevest for Bitcoin in the rare case that Bitcoin will need it and use it.

It's an interesting idea. I will spend some time to think about it more and see if doing this without a hard fork is possible. You basically have to somehow create incentives for Litecoin miners to also keep track of the Bitcoin blockchain. It may be as simple as checking a few bitcoin block explorers, but why would miners want to do that for no benefit... unless they are forced to by a hard fork.

Wouldn't miners running older Litecoin clients (if this was implemented in a new Litecoin release) be relaying the wrong information and not keeping a complete and correct ledger for Bitcoin?

I wonder what the implications of miners/users would be who do not upgrade their clients. Assuming a fork isn't required, if a miner doesn't upgrade are they now mining on a different chain? If not, wouldn't their blocks they create not be complete as it would not have the Bitcoin information?

I can see upgraded clients rejecting the blocks created by miners using the older clients as they would be missing the Bitcoin information that is required to be stored in the block that was created.



Title: Re: Using Litecoin To Protect Bitcoin Versus 51% Attacks - By Casascius
Post by: coblee on July 07, 2014, 08:36:42 AM
The reason why this idea did not take off originally was because people think that there was zero benefit to Litecoin and possibly no benefit to Bitcoin either. To do this, Litecoin miners have to maintain both the Litecoin blockchain and the Bitcoin blockchain. It will also require a hard fork on Litecoin for this to work. It's basically Litecoin holding on to a lifevest for Bitcoin in the rare case that Bitcoin will need it and use it.

It's an interesting idea. I will spend some time to think about it more and see if doing this without a hard fork is possible. You basically have to somehow create incentives for Litecoin miners to also keep track of the Bitcoin blockchain. It may be as simple as checking a few bitcoin block explorers, but why would miners want to do that for no benefit... unless they are forced to by a hard fork.

Wouldn't miners running older Litecoin clients (if this was implemented in a new Litecoin release) be relaying the wrong information and not keeping a complete and correct ledger for Bitcoin?

I wonder what the implications of miners/users would be who do not upgrade their clients. Assuming a fork isn't required, if a miner doesn't upgrade are they now mining on a different chain? If not, wouldn't their blocks they create not be complete as it would not have the Bitcoin information?

I can see upgraded clients rejecting the blocks created by miners using the older clients as they would be missing the Bitcoin information that is required to be stored in the block that was created.

You would do this with a miner vote. Basically implement this in the new clients. And have it in code such that when 95%+ of blocks mined in the last X blocks have this bitcoin hash data, then miners will enforce that every single block from then on must include bitcoin hash data. So this could take a long time (or never) but it will be relatively safe to do because when the fork happens, the majority of the miners are already running the latest code. And the minority would realize that they are on the wrong fork fairly quickly and would have to run the new code. Non-miners would be unaffected.

But like I've said, there's no good reason for miners to put in the extra effort to include bitcoin block data.