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[JorgeStolfi]

Variance would ensure that some blocks take longer or shorter to solve. Bitcoin regularly has block times of over 40 minutes.

The last 6 blocks have taken 80 minutes to solve, far from Bitcoin's regular 10 minute block time. I guess BCX is attacking Bitcoin as well.

The mean interval T between blocks depends on the current difficulty and the current hashrate.  Bitcoin's difficulty, IIUC, is adjusted at regular intervals to try to keep T at 10 minutes.  However, the adjustment is by large steps and is not instantaneous; so, if the hashrate drops for a while, or the difficulty has just been increased, T may be longer than 10 minutes for some time.  

In any case, even if the mean time T is exactly 10 minutes, the variance of the actual time between blocks is large, so the probability of having 6 or fewer blocks in an 80 minute interval is not that small.

I understand that Monero's difficulty is adjusted after every block instead of by steps, correct?  Even so, the algorithm would have to look at several past blocks in order to estimate the hashrate and compute the correct adjustment.  So, if there is an increase in the hashrate, it should take a while for the difficulty to be increased accordingly, and T would be less than a minute for a while.  And, in any case, the variance is substantial, for Monero too.

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[JorgeStolfi]

for the last 4 hrs, 240 minutes, 268 blocks were found.
How does this sound Jorge?

I understand that block finding is a Poisson process where the probability of finding a block in any small interval of time dt seconds long is dt/T where T is the mean time between blocks.  Then, the probability of n blocks being found in an interval with length t is
exp(-t/T)*(t/T)^n/n!

In your example, t/T is 240 and we want the probability of n being 268 blocks or more.  The answer is
exp(-240)*sum(k=268..oo  240^k/k!
That is not easy to compute, but for those range of values the distribution should be close to a Gaussian distribution with mean 240 and standard deviation sqrt(240).  So we can instead compute the probability of a standard Gaussian variable (mean 0, variance 1) being greater than r = (268 - 240)/sqrt(240).  I can't compute that right now, will do that later...

[psterryl]

for the last 4 hrs, 240 minutes, 268 blocks were found.
How does this sound Jorge?

I understand that block finding is a Poisson process where the probability of finding a block in any small interval of time dt seconds long is dt/T where T is the mean time between blocks.  Then, the probability of n blocks being found in an interval with length t is
exp(-t/T)*(t/T)^n/n!

In your example, t/T is 240 and we want the probability of n being 268 blocks or more.  The answer is
exp(-240)*sum(k=268..oo  240^k/k!
That is not easy to compute, but for those range of values the distribution should be close to a Gaussian distribution with mean 240 and standard deviation sqrt(240).  So we can instead compute the probability of a standard Gaussian variable (mean 0, variance 1) being greater than r = (268 - 240)/sqrt(240).  I can't compute that right now, will do that later...

Forgive me if I'm wrong but would that analysis not require the assumption of constant hashrate/difficulty over the period considered? If there is a sharp rise or fall in hashrate over the period then you will end up with some very improbable results.

[Oscilson]

for the last 4 hrs, 240 minutes, 268 blocks were found.
How does this sound Jorge?

I understand that block finding is a Poisson process where the probability of finding a block in any small interval of time dt seconds long is dt/T where T is the mean time between blocks.  Then, the probability of n blocks being found in an interval with length t is
exp(-t/T)*(t/T)^n/n!

In your example, t/T is 240 and we want the probability of n being 268 blocks or more.  The answer is
exp(-240)*sum(k=268..oo  240^k/k!
That is not easy to compute, but for those range of values the distribution should be close to a Gaussian distribution with mean 240 and standard deviation sqrt(240).  So we can instead compute the probability of a standard Gaussian variable (mean 0, variance 1) being greater than r = (268 - 240)/sqrt(240).  I can't compute that right now, will do that later...

Forgive me if I'm wrong but would that analysis not require the assumption of constant hashrate/difficulty over the period considered? If there is a sharp rise or fall in hashrate over the period then you will end up with some very improbable results.

We have an increased hash rate recently.

[JorgeStolfi]

Forgive me if I'm wrong but would that analysis not require the assumption of constant hashrate/difficulty over the period considered? If there is a sharp rise or fall in hashrate over the period then you will end up with some very improbable results.

Indeed, see my previous post.  The parameter T in those formulas is the actual mean time between blocks, defined by the current difficulty and current hashrate; not the ideal mean time.

[Febo]

But what would be point of this so called  "more blocks" attack? More Moneros daily issued? If not, that i don't really see any difference.  That is easily to check if something goes wrong.

[monero]

BCX, we'd like to formally respond to this -

So what was your reason for attacking Monero and refusing to allow devs to fix your exploit?  

They claim they've already TW proofed XMR and do not need any help.

~BCX~

In your post on September 17th you stated that you had found very specific exploits in Monero. Immediately, and in direct response to you, we asked if you could disclose the vulnerability to us privately so we could fix it. You did not respond to our request.

Subsequent to that post, in which you stated that you had no need or desire to attack Monero, you announced that you would be attacking Monero, and gave us 72 hours notice. At no point since we asked if you would disclose the exploit privately to us did we, formally or informally, claim that we had "TW proofed XMR". As it states in our ANN on Bitcointalk: "the official core team members are (in no particular order) - tacotime, eizh, smooth, fluffypony, othe, davidlatapie, NoodleDoodle". We cannot control what anyone else says of Monero, and if anyone has implied or stated that a TW-style attack is impossible that is not a view that we share. We are not naive enough to state that Monero is anything-proof, and we cannot categorically state that you do or do not have an exploit as you have not disclosed any details to us.

In addition, we have said and continue to say that Monero is alpha-level software, and is nowhere near the level of maturity Bitcoin has (and Bitcoin itself is considered beta software by its developers). We regularly have people providing assistance to the project, be it financial or direct effort or the imparting of some unique observation to us. We warmly invite and encourage assistance from everyone. We would never reject the offer of help unless we had a very specific reason to do so, and we most certainly do not reject your offer of help. We want to continue to make Monero better, and so any assistance you or anyone else can provide is deeply appreciated by us all.

Therefore, we openly and kindly invite you to disclose the details of the exploit to us privately so we may analyse and fix any exploits that may exist. You may do so by sending a private message to this account, sending a private message to any of the named core team members as listed above, or sending an email to dev@monero.cc

[vuduchyld]

this coin shall fall for months now.. bsx not attacking is bearish unless he says he cant attack.. chinese wont pump now. Never been wrong on my hunches from forex to cfds to crypto.. up to u. Check back in 6 months to c.

Wow...this guy has never been wrong on a hunch.  Impressive.

(stifles yawn)

[arielbit]

moringa and kamote leaves

Thanks for telling me about these, I love to try new foods.  You wouldn't believe what Whole Foods charges for moringa powder!

how much is your moringa powder there? i wish i could sell moringa over tcp-ip not just cryptos   ...my chat with an old friend of mine is laughing while talking about moringa, he said, what's the hype about moringa? aside from being a cheap food it is just a fence material..you stick it in between your lot and your neighbors lot and wallah you have a fence, you just have to trim it if you're gonna cook some leaves..in rural areas you can ask your neighbors that you are gonna get some from their plant and they give it away. in the market it is cheap like you just paid its transport.

[billotronic]

As someone with no skin in this game, it is very entertaining to see the demographics show themselves of people who are too new to the crypto scene to know that bcx tends to not fuck around, and those who do.

Good luck Monero, you will probably need it

[TooDumbForBitcoin]

As someone with no skin in this game, it is very entertaining to see the demographics show themselves of people who are too new to the crypto scene to know that bcx tends to not fuck around, and those who do.

Good luck Monero, you will probably need it

"...people who are too new ... and those who do."   Puzzling choice, there.

You forgot the third demographic - sychophants of BitcoinEXposed.  Good luck, Mr. President, you will probably need it.

[rangedriver]

As someone with no skin in this game, it is very entertaining to see the demographics show themselves of people who are too new to the crypto scene to know that bcx tends to not fuck around, and those who do.

Good luck Monero, you will probably need it

Since when has playing cocksucker to a risible antagonist been a virtuous pastime?

I must be getting old.

[CoinHoarder]

Time warp activated.

[TooDumbForBitcoin]

Time warp activated.

Didn't you post the same thing tomorrow?

[CoinHoarder]

Time warp activated.

Didn't you post the same thing tomorrow?

Wtffff. Yes I did. BCX is TWing Bitcointalk too. Leave now before you are taken back to 1822.

[TooDumbForBitcoin]

BitcoinEXpunged once timewarped a bottle of Stoli.  He made some of the Stoli go back in, but it was kind of chunky.

[randomlygenerated]

i just closed my eyes for a bit and then opened them up and it was 9 hours later?!?! i think i got hit by BCX time warp  is it true ?

[psterryl]

Indeed, see my previous post.  The parameter T in those formulas is the actual mean time between blocks, defined by the current difficulty and current hashrate; not the ideal mean time.

Ah yes, that's where I was getting confused. Thanks for the clarification.

[NewLiberty]

According to whom?  I think they might feel like they've uncovered some potential issues.  You demanded forced evolution.

I don't recall reading anything indicating that the dev team was ready to start licking each others' popsicles and throwing a victory party.  Certainly, that attitude exists, but, shit, trolling is everywhere.  Hard to demand forced evolution of the user/speculator base.

Try this.

~BCX~

Its over.  TW attacks will never again work against XMR.

If you read the last commit on github, you'll know the whole answer.
ANN here: https://bitcointalk.org/index.php?topic=583449.msg8961211#msg8961211


XMR Dev team rose to the challenge of forced evolution in the time available.
They have crafted a polymorphic bitmonerod+client that adds checkpoints at will and with no dev team intervention needed.  Its a decentralized self-maintainable solution that scales as needed.  Even if you DDoS github, checkpoints can still be deployed.

Thanks are due to BCX for initiating the game.  I hope it was rewarding, even though he was outplayed, this time.

If there are also some other anon-busters, but that don't rely on defanged TW, they're probably rested and ready for a rematch by now.

NewLiberty isn't part of the dev team.

True, I am definitely not a part of Monero Development team.  I'm nowhere good enough to be useful to them.  I'm just another innocent bystander enjoying the puzzles presented by BCX, and the merits of the Cryptonote technology as implemented in Monero.

So no comment at all from BCX on the merits of this evolutionary development?  Nothing at all good to say?  Not even an attaboy to those hardworking innovative developers who came up with something new to resolve an element of the TW attack vector universe within the 3 day challange?
I'll give it to them.  This innovation does resolve the classical TW attacks and defang them even when combined with DDoS.  It does this by decentralizing checkpointing.  

If BCX or one of the MUCH larger concentrations of computing power are looking to execute a new type of TW attack...  Say for example and attack designed to exceed the anomaly discards by relying on luckily matching one of a growing set of high difficulty hashes being databased with pre-computed sequential subsequent blocks... Then such an attack is 1) orders of magnitude more difficult, and 2) it requires a fortunate hash collision, and 3) it can take even a massive hashing effort a very long time to build such a block dataset to garner enough matches to hit an effect within the 720 block window of XMR and 20% anomaly discard.  

If something of that nature is contemplated, then such an attack would not be defeated by this innovation.  This innovation defeats only long chain TW attacks, which are the sort that are defeated by checkpoints.   That sort of new attack would be only defeated by actual mining, incrementally increasing over time.  This mining increase would ultimately obsolete the block dataset type of TW attack.  Its how Bitcoin did it.

The example blocks indicated in the previous posts do not present evidence of such an attack capability, at best they could show a test, but likely not even that.  So no.  Not spooked.  Not by that anyway.
===

BCX appears to have decided that more forced evolution is needed?  BCX is maybe awaiting acknowledgement, and a request to BCX for help, from the devs.

I'd ask myself, but 1) I'm definitely not on the dev team and 2) I've really nothing additional to offer.  Nothing except what I'd offer to Satoshi, that I would be helpful to his project when a time came that I could be helpful, and 3) It looks like they are in fact looking for your help here:
https://bitcointalk.org/index.php?topic=789978.msg8992099#msg8992099

ArtForz postulated novel vulnerabilities in block chain technologies years ago which were tested and executed by BCX and called Time Warp.  It works by saving up pregenerated blocks and releasing them later.  The main idea being that you can compress a lot of proof of work into a shorter period.  These Time Warp vulnerabilities present some dangers to all block chains in their infancy, including Bitcoin, typically by manipulating difficulty algorithms, and also by winning block rewards.  Bitcoin survived that period, we hope.  Every coin however, will have to struggle through this infancy period as hash rate rises.  All can be strangled in their cribs, even if they may grow up to be an improvement on the state of the art as we know it.


Bitcoin was not made for automating very high privacy transactions.   The current development direction is increasingly inconsistent with this.  That is then left to other new coins to experiment with.  And so, the fundamental innovations of Cryptonote, primarily the ring signatures, while possible to emulate in a rudimentary way with Bitcoin, is not something that is likely to ever become incorporated into Bitcoin.  Monero is the largest of these, if it falls, it clearly shows that all the others are much easier prey.  So, BCX may keep working on the game of sneaking into the nurseries and strangling babies while drinking Russian vodka, and others will keep on the game of looking for ways to be helpful for developing these technologies and saving the babies.  I'd like to see Monero grow up, so I'll keep doing what I can to protect the crib, and bring it the occasional bottle when I can.

[TooDumbForBitcoin]

You could make a lot money writing term papers.