What is it calculating/workng on?! | Bitcointalksearch.org

qbg

member

Activity: 74

Merit: 10

Quote from: Drumah on May 30, 2011, 11:42:00 AM

Not to be very blunt....

But what would stop someone from hiring a botnet of 30.000 PC's, install a shitload of modified clients and poison the network into uselessness with false transactions ?
As long as those 30.000 PC's are spitting out 'valid' packets of what they say is true, there's a lot of legitimate CPU/GPU power needed to counter that..

Just a thought though Cool

The unmodified clients won't accept the invalid blocks generated by the modified clients, and so the coins produced by the modified clients won't be accepted by the other users. In effect, the person ends up creating a new currency accepted by no one.

rebuilder

legendary

Activity: 1615

Merit: 1000

Quote from: JA37 on May 30, 2011, 12:12:16 PM

But leaving your cpu running will theoretically allow you to find a block, and as such cash in almost $500, right? Odds aren't worse than playing any regular lottery?

The odds in a regular lottery are dismal.

JA37

sr. member

Activity: 378

Merit: 250

It does if I run it on someone elses power (like a client) and it's a company laptop. Wink

It's not like they can tell what I'm running on the machine I bring to the office.

rezin777

full member

Activity: 154

Merit: 100

Quote from: JA37 on May 30, 2011, 12:12:16 PM

But leaving your cpu running will theoretically allow you to find a block, and as such cash in almost $500, right? Odds aren't worse than playing any regular lottery?

Well, does your CPU run for free?

JA37

sr. member

Activity: 378

Merit: 250

But leaving your cpu running will theoretically allow you to find a block, and as such cash in almost $500, right? Odds aren't worse than playing any regular lottery?

gigitrix

hero member

Activity: 630

Merit: 500

Quote from: Drumah on May 30, 2011, 11:42:00 AM

Not to be very blunt....

But what would stop someone from hiring a botnet of 30.000 PC's, install a shitload of modified clients and poison the network into uselessness with false transactions ?
As long as those 30.000 PC's are spitting out 'valid' packets of what they say is true, there's a lot of legitimate CPU/GPU power needed to counter that..

Just a thought though Cool

30,000 PCs probably wouldn't leave much of a dent on the infrastructure we have now. Also, botnets are quite expensive, and more money can be made doing other stuff with them.

Drumah

newbie

Activity: 2

Merit: 0

Quote from: rezin777 on May 30, 2011, 11:47:30 AM

Quote from: Drumah on May 30, 2011, 11:42:00 AM

But what would stop someone from hiring a botnet of 30.000 PC's, install a shitload of modified clients and poison the network into uselessness with false transactions ?

Math.

That contradicts:

Quote

THe fact that the network has more CPU power than me - and can generate more "proof of work" than me - makes that impossible. I could make 1 fake block at best, but it would be overwhelmed by everyone else's blocks and my money would quickly be recorded as spent.

If criminals would utilize one of the bigger botnets to do some heavy duty poisoning by sending out fake transactions and re-spending their coins over and over again. It's all a matter of who has the most CPU power then, that makes Bitcoin very attractive to attempt and exploit this for owners of large botnets, wouldn't it ?

rezin777

full member

Activity: 154

Merit: 100

Quote from: Drumah on May 30, 2011, 11:42:00 AM

But what would stop someone from hiring a botnet of 30.000 PC's, install a shitload of modified clients and poison the network into uselessness with false transactions ?

Math.

Drumah

newbie

Activity: 2

Merit: 0

Not to be very blunt....

But what would stop someone from hiring a botnet of 30.000 PC's, install a shitload of modified clients and poison the network into uselessness with false transactions ?
As long as those 30.000 PC's are spitting out 'valid' packets of what they say is true, there's a lot of legitimate CPU/GPU power needed to counter that..

Just a thought though Cool

casascius

vip

Activity: 1386

Merit: 1140

The Casascius 1oz 10BTC Silver Round (w/ Gold B)

Quote from: TiagoTiago on February 23, 2011, 04:01:08 PM

A modified client? Would that modified client be able to insert artificially created money (versus "naturally" occurring money that is found with mining) into the network, the illusion ends at the modified client?

What if the bad block include the emergence of mined money (currently 50BTC) ? How does the network prunes false births of bitcoins?

Correct, illusion ends at modified client.

If a block is thrown out, the mined coins are thrown out with it. That is why you have to wait a certain period before you can spend mined coins, to make sure they aren't void. (example, if 2 people solve the same block at the same time, one of them will be completely rejected by the longest proof of work rule within two or three blocks).

TiagoTiago

hero member

Activity: 616

Merit: 500

Firstbits.com/1fg4i :)

A modified client? Would that modified client be able to insert artificially created money (versus "naturally" occurring money that is found with mining) into the network, the illusion ends at the modified client?

What if the bad block include the emergence of mined money (currently 50BTC) ? How does the network prunes false births of bitcoins?

casascius

vip

Activity: 1386

Merit: 1140

The Casascius 1oz 10BTC Silver Round (w/ Gold B)

Quote from: theGECK on February 23, 2011, 03:18:47 PM

I'm assuming all CPUs because the OP here was talking about what the bitcoin program was working on, and because of the discussion in another thread talking about adding a 10% "CPU donation" to the bitcoin program, which most people who aren't interested in mining would be running.

Where did you find the stats about total hash power, users, etc? Also, would slush's pool count as one "user", or were you referencing the average of slush's pool?

Bitcoincharts.com shows the estimated total hash power on the network.

It is impossible to tell how many users there are, since 10 computers hashing at 50MHash/sec look exactly the same as 1 computer hashing at 500MHash/sec. The hash power is estimated simply by multiplying the number of blocks that are appearing in the block chain, by their presumed difficulty in creating them per unit of time.

Since users aren't countable, it doesn't matter whether mining happens in Slush's pool or out of it. It's strictly a function of how many solved blocks are appearing, a block made in a pool calculates the same as one made solo. The only difference with a pool is that the booty is divided up afterward.

casascius

vip

Activity: 1386

Merit: 1140

The Casascius 1oz 10BTC Silver Round (w/ Gold B)

Quote from: TiagoTiago on February 23, 2011, 03:49:51 PM

I'm sorry, i'm not seeing it clearlly, how exactly does other people finding blocks of transactions after the fake transaction results in them indentifying that the fake transaction was fake? Or the other people are actually calculating the same block several times till their blocks agree with the blocks their neighbours calculated?

First there is no such thing as a "fake" transaction... the fraud would be the omission of a real transaction. A transaction that is fake on its face (i.e. sends bitcoins that don't exist) won't be accepted by any unmodified client, whether in a block or otherwise. (If it were in a block, the block would be rejected).

If I am a fraudster, what I am trying to do is generate blocks that omit registering money i have spent, so I can try to spend it again. But once someone else successfully generates a block that includes the missing transaction, I'm hosed. If I own more CPU power than the rest of the network, I can continue to generate blocks that override the blocks I don't like (and have mine overrule by the longest-proof-of-work rule), but since I don't have the majority of CPU power, I can't create the longest proof of work, and I'm stopped from the attack.

TiagoTiago

hero member

Activity: 616

Merit: 500

Firstbits.com/1fg4i :)

I'm sorry, i'm not seeing it clearlly, how exactly does other people finding blocks of transactions after the fake transaction results in them indentifying that the fake transaction was fake? Or the other people are actually calculating the same block several times till their blocks agree with the blocks their neighbours calculated?

theGECK

sr. member

Activity: 411

Merit: 250

I'm assuming all CPUs because the OP here was talking about what the bitcoin program was working on, and because of the discussion in another thread talking about adding a 10% "CPU donation" to the bitcoin program, which most people who aren't interested in mining would be running.

Where did you find the stats about total hash power, users, etc? Also, would slush's pool count as one "user", or were you referencing the average of slush's pool?

BitterTea

sr. member

Activity: 294

Merit: 252

Quote from: theGECK on February 23, 2011, 02:54:25 PM

Essentially, since you have so many people buying raffle tickets, the person who wanted to do it would need to buy more and more. For every 100 of my CPUs that donate 100% of their available power to the network, an attacker has to buy 2 5970s to equal it.

I'll be honest, that doesn't seem like much of a hurdle to climb. Right now slush's pool has 900 workers. Assuming that each of them is a separate computer (not likely), if each of their CPUs were mining, that would mean that an attacker would need to have 18 5970s to equal their power. That's not a large investment for the ability to manipulate an entire currency, but perhaps I'm missing something. I'm sure that there are more than 900 people mining, right?

Is there a way to find out how many people are actually mining? Is "mining" the only way to strengthen the network?

A lot of people using Slush's pool are GPU mining. I'm not sure why you're assuming all CPUs.

From the stats, Slush's pool currently has a hashrate of 114.518 Ghash/s, with the total network hashrate is 366.33 Ghash/s. That means that Slush's pool has around a third of the total computing power of the Bitcoin network, the "average" pool user has a hashrate of 128 Mhash/s (much higher than a CPU), and an attacker wishing to equal Slush's pool in power would have to bring ~190 5970s online.

theGECK

sr. member

Activity: 411

Merit: 250

Quote from: casascius on February 23, 2011, 02:31:40 PM

That's what we mean when we say people mining "strengthens" the network - it raises the hurdle for an attacker higher and higher to the point it's hardly worth their while.

Essentially, since you have so many people buying raffle tickets, the person who wanted to do it would need to buy more and more. For every 100 of my CPUs that donate 100% of their available power to the network, an attacker has to buy 2 5970s to equal it.

I'll be honest, that doesn't seem like much of a hurdle to climb. Right now slush's pool has 900 workers. Assuming that each of them is a separate computer (not likely), if each of their CPUs were mining, that would mean that an attacker would need to have 18 5970s to equal their power. That's not a large investment for the ability to manipulate an entire currency, but perhaps I'm missing something. I'm sure that there are more than 900 people mining, right?

Is there a way to find out how many people are actually mining? Is "mining" the only way to strengthen the network?

casascius

vip

Activity: 1386

Merit: 1140

The Casascius 1oz 10BTC Silver Round (w/ Gold B)

Quote from: TiagoTiago on February 23, 2011, 02:08:31 PM

So, if a single person finds a good hash for a faked block they can get away with it? I thought there was somthing with the network evaluating the job done to confirm if somthing makes sense...

More like this: if I spend money, but keep generating blocks that lack the transaction, I could in theory get away with spending the same money over and over again, because nobody will recognize the money is already spent.

THe fact that the network has more CPU power than me - and can generate more "proof of work" than me - makes that impossible. I could make 1 fake block at best, but it would be overwhelmed by everyone else's blocks and my money would quickly be recorded as spent.

The ability to manipulate the block chain doesn't confer the ability to counterfeit or forge transactions, it would at best simply let someone get away with "kiting" their bitcoins and take back money they already spent. Someone would have to control more than 50% of the total hashing power across the whole network to pull that off. That's what we mean when we say people mining "strengthens" the network - it raises the hurdle for an attacker higher and higher to the point it's hardly worth their while.

TiagoTiago

hero member

Activity: 616

Merit: 500

Firstbits.com/1fg4i :)

So, if a single person finds a good hash for a faked block they can get away with it? I thought there was somthing with the network evaluating the job done to confirm if somthing makes sense...

Gavin Andresen

legendary

Activity: 1652

Merit: 2301

Chief Scientist

Bitcoin is confusing at first glance because so many problems are solved using just a few ideas. If you think about it long enough, it is quite elegant.

The busy-work of finding a block hash that is "small enough" solves a couple of problems:

First, by making it hard to create coins so they are artificially scarce. That is really important; if it was easy to create gazillions of bitcoins we'd all have gazillions of bitcoins that were worth nothing.

Second, it solves the double-spending problem-- the computer that solves the busy-work problem first gets to decide which transactions are "THE" transactions, and which ones are invalid (because you're trying to spend coins you've already spent).

Topic: What is it calculating/workng on?! (Read 10805 times)