Bitcoin Forum

When I tell people I work on Bitcoin full-time, a somewhat common reaction is "Really?  I thought Bitcoin was finished, what do you work on?"

I spend half my development time working on new stuff (or testing new stuff that other people have submitted), but the other half I spend trying to anticipate problems or reacting to problems that are reported. That work tends to be unseen, partly because we want to keep problems quiet while we fix them and partly because quietly anticipating/fixing problems minimizes the 'lulz' that attackers might enjoy if every single-node-DoS attack caused us to run around like chickens with our heads cut off.

Anyway, good developers are hard to find, and one of the reasons I'm not thrilled by all of the AlternaCoins is because I'd rather a good developer help make Bitcoin better rather than spend their time with the busy-work of cross-porting the latest Bitcoin fixes to some other codebase. I would guess that some of the developers of the alternative chains underestimated the amount of work it takes to nurture them and keep them healthy. Maybe that will change when Bitcoin is truly mature and has dealt with another year or two or six of attacks and scaling issues...

I truly don't mean this to sound like a threat, but I think some of the blockchains that have been chugging along running on an ancient forked version of the Bitcoin codebase will be attacked; pretty soon we'll be fully disclosing the denial-of-service bugs that prompted the 0.6.2/0.6.3 releases, and it is highly likely somebody will decide to play with exploit code on a vulnerable chain.

I wish people would find more constructive things to do with their time, but I wish I could fly and never get old like Peter Pan, too.

The amount of work required to maintain the alt-coins can be easily reduced by more than an order of magnitude.

Just cease to maintain them as forks in the github sense.

They need to be rewritten to Perl or other text-processing language.

The input to said Perl program should be the Bitcoin source tree and the list of the rather trivial changes that need to be made to various constants and identifiers in the Bitcoin source.

The output will be altcoin source tree buildable in the exact same way as the Bitcoin source tree.

This is a proven methodology that was in use when the source programs were in Fortran and the text processing language was Snobol.

Well to date, no altcoin has done much other than tweak a few variables which doesn't take much in the development department. Solidcoin developers attempted a rewrite with microcash and have since disappeared before release without a word.

And then there are those that believe bitcoin has significant flaws that cannot be fixed by software updates and choose not to work on bitcoin.

How's the fix for the 'time travel exploit' in bitcoin going? That was found and fixed in alt chains a while back. I know you don't like alt chains but some of the stuff that's resulted from them have improved bitcoin - particularly edge case bugs as a result of attacks on the coins (The time travel exploit, the database log file growth bug a while back, etc).

I don't think Bitcoin requires that fix. The feedback system in Bitcoin is either asymptotically stable in the Lyapunov sense or extremely close to being asymptotically stable. By extrememly close I mean that the maximum amplitude of oscillations that could be introduced in it is on the order of LSB in the very narrow floating-point format that is used to represent the difficulty.

On the other hand the designers of alt-coins cranked up the gain in the feedback loop and applied asymmetric clipping in the feedback signal. The resultant system is probably still stable in the Lyapunov sense but no longer asymptotically stable.

Satoshi either understood the stability problem in the theory of closed-loop control systems or at least consulted somebody who understood the problems.

On the other hand the designers of alt-coins are like kids who stood up with microphone in front of the speakers and cranked up the gain on the amplifier.

http://en.wikipedia.org/wiki/Lyapunov_stability

+1

I think alternate chains are a test bed for bitcoin. But just because Gavin you probably have a high stake in bitcoin ( i suspect) that shouldn't be a reason to try to get people to develop on the original bitcoin network.

People will do what they want with their time, just as you are.

I think having an alternative to bitcoin is a good thing in that it gives the new comers a CHOICE other than just having Pepsi or just MacDonalds.

Gavin, here's an idea: generalize the official client to handle multiple coins from the same codebase, or otherwise make it less difficult to maintain patches between codebases.

People will work on whatever scratches their itch. The onus is on you, the core developers, to make the development process receptive to incoming talent.

Gavin, I think you need a coffee and bagel intern.

2112, I'm not entirely sure if you've looked at the code for GetNextWorkRequired. You keep describing it as doing integration when from what I can tell its entirely proportional. Are you making assumptions looking at the graphs on this website? http://bitcoin.sipa.be/

Here is a condensed version of the code with my comments:

//pindexLast points to the last block generated. pindexFirst points the block generated 2015 blocks ago.

if ((pindexLast->nHeight+1) % nInterval != 0)  //nInterval is 2016
return pindexLast->nBits;

//some code to get pindexFirst and limit the gain of the proportional controller to a threshold.

int64 nActualTimespan = pindexLast->GetBlockTime() - pindexFirst->GetBlockTime();

bnNew.SetCompact(pindexLast->nBits);
bnNew *= nActualTimespan;
bnNew /= nTargetTimespan;  // target is 1209600 (two weeks)

The reason this is safe is that the Bitcoin protocol enforces a rough causality for every block accepted onto the network.

My reason for posting this is I'd like to get your opinion on how safe the implementation is.

As far as the graphs on sipa's website, only the difficulty actually exists. The estimates are calculated in this way.

Gavin--

What is this post about?

Did somebody say something stupid to you?

We appreciate all the work that you do on Bitcoin.

What is version .0.6.3? The latest version available to the public is .0.6.2.

Thanks.

Don't know why but I see this as a warning to coblee and LTC abou Luke coming to attack the chain :'(

Hope it does NOT happen because that is NOT cool and anti competitive BS just like the government and status quo like ...

Same difference. There is a 2016-way decimator (or subsampler) at the output of the I or PI controller.

The decimator is there to assure that the blockchain converges after an emergence of orphans right after the difficulty retarget. Without the decimator the blockchain would either completely split or took much longer time to converge to a majority.

The I vs PI argument is somewhat hair splitting because if it is PI then the proportions are about 1/2016 P and 2015/2016 I. Additionally there is at least one off-by-one bug in the computation of the feedback value so the equations aren't optimal but about 1/2016 away from the optimal.

Incidentally (or by design) integrator is also an approximation of an average. And average happens to be maximum likelihood (or maybe minimum variance or some such) estimator for the lambda parameter in the exponential distribution governing the block-winning lottery.

I have a feeling that Satoshi had a very peculiar sense of humor, intentionally setting a traps for people who kinda but not really understand what's going on. Very similar to the choice of stochastic knapsack solver for the wallet coin selector. I now always imagine him cackling at the discussions here from a safe distance.

Hey Gavin, how about PM coblee and DoubleC about these exploits so they can begin work on the alt chains if they so choose to?

Why the secrecy?

Gavin, perhaps you should consider the good things about alternative chains--

1) Keeping other block chains in mind promotes writing "good", bottom-up code where everything is properly encapsulated, and easily extendable by the alternate chain authors. Obsession with "good" code can be taken too far, but programming with alternative chains in mind would actually help you improve the official client.

2) Additionally, the kinds of changes many have suggested to improve the official client's alternative currency support would improve Bitcoin itself. For instance, etothejpi's tree of unspent outputs is a type of alternative chain. Additionally, namecoin is another alternative chain that has some practical value to Bitcoin users.

3) As others have pointed out in this thread -- Alternative currencies help to highlight bad design decisions and why Bitcoin, at the moment, is superior. You can learn from others mistakes.

4) Alternative chains are absolutely necessary for the long term success of Bitcoin. Remember what proof of work was before Bitcoin? It was used as a type of digital notary stamp to prevent spam e-mails.  Proof of work is a digital token that says "I invested some amount of time and computational effort in solving this problem." The primary future use of Bitcoin will likely be supplemental to the actual crypto-currencies most people use. Bitcoin's role in a future economy will be much like the role of the Bureau of Engraving and Printing in the early history of the U.S. Dollar when employees of the U.S. Treasury would sign the individual bills produced by private companies for the Treasury. The role of the signature was to "monetize" the paper, much like the role of the Bitcoin will be to "monetize" alternative currencies.

Rereading my original post, I should make clear: the people I really have issues with are the people who think it is more fun to try to destroy something than to help build it.  My comment about "I wish people would find more constructive things to do with their time" was not meant to be aimed not at AlternaCoin creators.

I agree that there are some benefits to the alternate chains existing; I just wonder if the costs of all the duplicate infrastructure (exchanges and pools and faucets and...) is worth the benefits.

RE: privately disclosing exploits to AlternaCoin developers: well, to be frank, I have no idea if most AlternaCoin developers can be trusted with sensitive exploit information or even who is currently supporting which chain. The danger would be somebody emailing me claiming to be the lead developer for FooCoin, I tell them about the vulnerability, and then they turn out to NOT be the lead FooCoin developer but an attacker.  Or I tell FooCoin about the vulnerability and they decide to use it to launch an attack on their arch-enemy, BarCoin.

It is all drama and heartburn that I'd really rather not have (again, costs and benefits....)

Gavin, that's why you send it to people who are trusted in the community.

For all we know you could be a terrorist with all the exploits right? So what's the difference? You made an impression on the forum...so can others. You're not special bro...

Gavin, I misinterpreted your original posting and I apologize for the passive aggressive hostility. You do good work; keep it up.

There are probably about 7 running and 2 probably have dropped out this year (geistgeld and liquidcoin?).  Due to the numbers none have them gained any traction, the numbers weaken them.  If there were only 1 or 2 like namecoin and microcash, they would be a lot more powerful.  The secret is out cryptocurrencies work.  People are going to try to get in on the ground floor and start new coins.  It seems you are offering request for help in the main coin, bitcoin.  Maybe you can ask them directly for help.

+1

that doesnt exist lol

It will be released on the 10th! ;)

To be honest Gavin, I think it's a question of Ownership. Bitcoin hit GPU mining before it hit mainstream- and thus those who weren't early adopters feel left out. Sentimental? Yes, but not irrelevant. If the cost to entry is a serious GPU farm, many casual people who would over time get seriously committed if they had a chance, are lost. Bitcoin is great for all the reasons we all know, but for ordinary people (especially those not fond of math) selling them on bitcoin is like selling them a piece of the moon.

One could make the argument that if the wave of individuals who got involved in alternacoins like LTC (thanks to Bitcoins PR) is greater then the original Bitcoin early adopter crew, there is a chance that in the long run a Larger AlternaCoin community might make a more viable concurrent currency system.

By day I'm a reasonably well known fashion photographer- hardly the kind of guy you would expect to get involved. But here I am, and I'm mining LTC because I can. I also have an incentive to spend the summer learning to program so I can build apps that use LTC to raise the value of the LTC I've already mined. Hopefully LTC remains somewhat viable for people to mine long enough to get an even larger group of invested new-early adopters.

We all like bitcoin- no doubt about it, but for me to have to go through a still very lengthy (bank transfer to exchange) or costly (bitInstant is not cheap) process to get bitcoins just to turn around and buy things I could buy anyway with a credit card- doesn't rock my boat in quite the same way.

I understand the why/how of Bitcoin, but I think a sense of ownership that coins like LTC still offer is very powerful.

Imagine this- The United States was conquered al'la Manifest Destiny in many ways thanks to the free opportunity of ownership that the "west" offered. Gold rush or land rush, the idea was to distribute potential wealth as widely as possible so that you suddenly had a great number of people invested in the idea of "America". I lived and studied in great depth and many years in the former Communist states and a key principle in converting Communists countries to Capitalist societies was redistribution of wealth. It wasn't perfect by a long shot, but it got people invested in a sense of ownership in a free society.

Coins are quite the same. They need to be distributed as widely as possible to ensure a user base of support- the primary mechanism of this is mining. BTC is already relatively elite to mine, but I think it's questionable if it grew it's user base large enough prior to becoming relatively elite.

An alt Coin like LTC has an opportunity to build on BTC's success and gather a wider user base while (hopefully) keeping mining an option for more users, longer.

In the end, I think it's not about the coin- it's about the IDEA of bitcoin. If one succeeds more or less then another it's somewhat irrelevant- if any of them succede it's a victory for the philosophy. That's more important no?

 

BRAVO! Well said.  ;D

+1

It is a shame all of the Bitcoin developers don't agree with this.
Unfortunately I cannot legally copy and paste the freenode #litecoin IRC logs on this forum.

and when the Bitcoin devs have finished welcoming asics there will be plenty of people looking for alternaate uses for their cpus and gpus maybe a viable alternate coin would suit them.
Bitcoin is alienating many of the people that supported it for a long time by welcoming ASIC technology and driving out the small "hobby user"

my 2LTC worth

Litecoin is vulnerable to even CVE-2012-1910 (https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2012-1910) which was disclosed back in March.
I've created a pull request to fix it (https://github.com/coblee/litecoin/pull/44), mostly as a test for the Litecoin maintainer(s).

Additionally, I've confirmed that CVE-2012-2459 (fixed in Bitcoin 0.6.2) (https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2012-2459) and CVE-2012-3789 (fixed in Bitcoin 0.6.3) (https://en.bitcoin.it/wiki/Common_Vulnerabilities_and_Exposures#CVE-2012-3789) would both be trivial to port fixes to Litecoin once disclosed.

P.S. This is not an endorsement of Litecoin in any way. It is still a scamcoin, after all.

Agreed. One person in particular would be Luke-jr from what I hear he has nothing better to do than to try to destroy something.

How is it a scam coin? No one premined anything...

Translation of the Red: "I am heavily invested in bitcoins thus any other alternative to bitcoin as a digital currency is a "scam"".

https://en.bitcoin.it/wiki/Litecoin#Criticism

Perhaps you know the future better than the rest of us. You appear to know what will happen or will not happen.

So those "criticisms" could have been made when bitcoin was only 8 months old eh? What's the difference? Bitcoin was vulnerable then and who knows what may happen in the future to change the status quo of digital currencies.

I love this quote: "This is not the case for Bitcoin, since it has significant potential to become a long-term currency and continually be beneficial to adopters no matter when they begin using it."

So then when bitcoin say goes to $100 or even $1000 and then the price drops to say $20 then if someone got in at $1000....as the quote says "and continually be beneficial to adopters no matter when they begin using it."

LOL

See my statement is hypothetical and in the future which neither of us know. So same as the statement that litecoin is a scam and will fail is a future statement which has not transpired to date.

No, Bitcoin did not have a preexisting currency with all the same features to compete with. Nor does Bitcoin have the growth-paralyzing proof-of-work known as scrypt.

What basis is there to expect that will happen? (I already presented my case for why Litecoin is almost guaranteed to fail)

bro you must have missed the last rally to $32/btc and back to $2?

LOL that's why!

It's called SPECULATION. Google it.

But Luke, it doesn't really matter if Litecoin is a slightly tweaked copy of Bitcoin. No one criticizes small countries for printing their own currencies even when there are already other currencies out there. No one complains when this countries small currency isn't as counterfeit proof as the American Dollar (or what-have-you). Bitcoin and Litecoin are sovereign unto themselves as the group of people who believe/invest in them.

As for growth paralyzing, let me use an analogy that I suspect may one day come back to haunt me but I think a fair number of adults will understand:

The Penis.

A large number of men will tell you they worry about size, and by this they generally mean length. It's all about the Inches, the CM, "how long is the dong".

But a vast number of women will tell you it's about the girth- not the length. And indeed longer isn't always better- with longer sometimes just being too long if not wide enough.

How does this relate to Bitcoin/Litecoin? Well bitcoin is big as in long (hashing power), (and about to get a whole lot bigger/longer with ASIC) but it's not necessarily big as in wide (girth). If litecoin can be wide (IE: wide user base) even if it's not so long (hashing power) and this hashing power doesn't grow so fast, it still has a good chance of being a 'perfect fit'.

So, hopefully this makes a nice analogy without getting deleted as inappropriate.

Ah, the Bitcoin Penis Analogy. I was waiting for that. Finally I can print bumper stickers that say "Bitcoin: mine it til it Hertz!". Or "My blockchain is longer than yours". Or "Is that a Bitcoin Wallet USB key in your pocket, or are you just glad to see me?".

Sorry about OT. It just had to be said.

"I lived and studied in great depth and many years in the former Communist states and a key principle in converting Communists countries to Capitalist societies was redistribution of wealth. It wasn't perfect by a long shot, but it got people invested in a sense of ownership in a free society. "

That is the definition of communism or socialism.  Capitalism you get to keep your labor or returns of capital and pay taxes as a choice mainly for protection or to enforce law.

"Since the aforementioned reasons mean Litecoin has no future potential, it effectively functions as a pyramid scheme, rewarding those who get in sooner at the expense of those who adopt it just before it finally fails (and are left with nothing). This is not the case for Bitcoin, since it has significant potential to become a long-term currency and continually be beneficial to adopters no matter when they begin using it. "

Although probably a correct statement, but they think it will last forever thus not a ponzi scheme.  Same can be said about BTC regarding blockchain size.

Yes, but your forgetting that when going from a communist or socialist state to a capitalist free market society, it is the state that is initially in possession of all wealth- thus it is necessary to redistribute the wealth AWAY from the centralized state and disburse it private individuals. 

Redistribution of wealth works in many different ways depending on the situation. In capitalist societies for example, an estate tax is a form of redistribution of wealth as it takes (hopefully a large) chunk of a dead persons estate as taxes, and the government then spends that money elsewhere  (hopefully on things like education).
Rich people like to avoid the estate tax and thus frequently donate away most of their wealth prior to their death, which is also a form of redistribution. Grandkids hate it, but it's a pretty fantastic mechanism when you think about it.

Considering 4x block rate and 1mb block size limit Litecoin will be capable of handling 4x more transactions than Bitcoin before hard fork is required. With current Bitcoin blocks approaching 256kb it can only grow 4x before it would hit that limit.

It's better to spend time on scalability of Bitcoin than attacking other chains.
At some point Litecoin might serve as a backup chain while Bitcoin will be choking on 1mb 10min blocks.

EDIT: this post isn't meant to ignite Bitcoin/Litecoin flame war and is not directed at anyone personally.
Just an observation of facts about two chains that might make a difference in the future.

I prefer to compare crypto-currencies to chemical elements we discover.
We first discovered Bitcoin. We studied its properties, figured out it was stable and found a good number of ways we could use it in our lives. Some of us said "Bitcoin works for me, I will use it and I don't need anything else", while others kept searching for new elements.

As time went by, through the series of experiments (Tenebrix, GeistGeld, Fairbrix, Liquidcoin) which were all unstable isotopes and decayed quickly, we then discovered Litecoin. It turned out to be quite stable even though it wasn't obvious at a time. We now know that it has certain characteristics different from Bitcoin that might make a difference in the future. Thus some of us decided to use it as well.

I believe in the future there will still be search for new elements, there will still be experiments and I'm sure there will be new stable elements we haven't even thought of yet!

Alterna-coins are a natural outgrowth of bitcoin introducing a new idea into the ideasphere; the fact that it is open source makes cloning the idea trivial.  Alterna-coins were always inevitable.

If someone can come up with a better bitcoin than bitcoin -- that's great!  Humanity benefits from the competition.

Speaking as a developer, though, contributing patches back upstream would be nice :)

Because of the insensate network effect no AlternaCoin stands a chance against bitcoin - unless it offers valuable additional features.

hint: check out my signature  ;D

Gavin,

This problem (with out-dated bitcoin code running on alternative chains) is exactly why I have been advocating for so long to build new user currencies on top of bitcoin, much like HTTP is built on top of TCP/IP.

Over and over again we see that once a person truly grasps what bitcoin is and the magnitude of what it could be, they inevitably want to try their hand at making a "better bitcoin".

Rather than fight this instinct, I believe we should embrace it. Once we have tools which users can use to build their own alt-coins on top of bitcoin with no programming required (as I have written about extensively), we will see the explosion in adoption that has always seemed just around the corner.

I've sent a few patches upstream. Well, here's one more:

https://github.com/bitcoin/bitcoin/pull/1536

Litecoin was attacked with dust spam where the attacker would send a transaction with thousands of outputs of a satoshi each. Yet, they only get charged the base fee. This fixes it by making the fee grow linearly with number of dust spam.

Awesome. LTC clearly makes BTC strong.

Disclaimer I have healthy investments in both.

It would be handy to isolate various coin-specific constants used in the code, such as the symbol displayed, the icon(s) displayed, the word used as label to label that coin distinct from other coins, all the stuff users see, as well as the simple things that change from coin to coin such as genesis block, genesis block hash, all the things multicoin isolated into a config file.

It would be much easier to contribute patches back then because the code being patched would be much more up to date.

-MarkM-

+1