Yes the 51% miner could attack with two alternating chains as you describe but I am not sure what the advantage is from the attacker's perspective.

Given 51% or greater mining power, the attacker can simply mine it's own chain with whatever transactions it wants to use and it will as a matter of statistics get ahead of any other chain that the remainder of the mining community can produce. 

It is this ability to get ahead on the chain with valid proof of work that allows that attacker to always get long term control of the chain and fork it in the direction the attacker wants to go.

The attacker could choose to include all other transactions (good behavior), double spend (fraud), filter out particular transactions or transactions from particular address(s) (targeted denial of service),  reject all transactions (complete denial of service), long term reject block solutions from any subset of miners  (monopoly)

So the question back to OP is, "What extra advantage does the dual chain attack he describes give to the 51% attacker?" 

My refund is now 19 blocks deep in the Blockchain.    I call that confirmed and done.   

If the BTC is confirmed back to your address in the blockchain that is a much more permanent and sure record that the transaction is a done deal than a flaky wallet app.  Just check it at blockchain.info.

When ever I create any new address in a wallet, the next thing I do immediately is a wallet backup, encrypt and archive.  That way any transactions to the new addresses are now independent of the wallet since I have a fresh backup that includes all public and private keys for the new addresses and all my old addresses.  

Sent request to support@minersource.net

Original request on Feb 10 via PM to bobsag3

Contents of minersource e-mail just sent will match exactly the details in followup PMs on Feb 13 and March 5 to bobsag3

Still waiting on my refund request from Feb. 10 as well.    Only 12 shares.   3rd PM sent today

Hopefully BobSag3 is picking up some Bitcoin at the current prices to pay us back so the hit on DZ is less.

When I bought most of my DZ shares, Bitcoin was over $800 I think.

I have been picking some up today and almost all of it in the 400's.

Lowest price I bought at was $408.

Have to celebrate something on this thread.

A post on the main R17 thread, plus 2 PMs with full details of share purchase numbers, e-mail, Hashed signature message and "please contact if you need any further information."  Nothing.

2 weeks have transpired since I requested my refund of 12 shares on Feb. 10.    No response at all on my request.

After running over 24 hours on Eligius with its own payout address, the Eligius reported performance matches the local performance, about 1.62 TH.

I am still running into the problem where one of the "cores" will sometimes stop hashing and total hash rate will drops by about 100 GH both locally and on Eligus.  Manifests like this in the stats.

http://i.imgur.com/npJNrBn.png

ASIC1Core1 obviously the one not hashing.

http://i.imgur.com/N3jbVyC.png

A reset of the machine gets that downed core running again and the hash rate up above 1.6 TH again.

You can see in the Eligius plot the rate drop down about 100 GH about 4 hours before Feb 19th.  Not sure what causes this intermittent outage of a core for a long duration.  And it has always been this same core and similar symptoms.

http://i.imgur.com/5M4ac1f.png

... sent inquiry on this to Cointerra

From the Cointerra user guide.

"To boot up the TerraMiner IV connect the power cords within 3 seconds of each other. If they are not both powered up within this time it is possible that the BeagleBone controller card will not recognize both GoldStrike boards inside the TerraMiner."

There is a ton of detailed status information that can be seen in the Advanced/Stats page.  You can see the performance of each of the 8 cores on each ASIC including, hardware errors,  voltage and temp.    I have seen issues with one core on each ASIC that have shown as low voltages and hardware errors.   Right now seeing no issues on any cores.  Not sure if these were intermittent issues or perhaps some temp related issues on the first day of operations.

I am managing a Cointerra for the first month of its life.  I have the two plugs running off of two separate 110v circuits, which they recommend as well.   You can try unplugging and replugging as a restart. (I have done a few of those type of restarts) You also have have the small hardware reset button on the front panel that you can press with the end of a paperclip.  (I have done a couple of those restarts)

Due to Eligius stats collection and reporting issues, I couldn't get a new payout address on Friday.  So for the first 3 days I had the Cointerra paired up with an Antminer to the same payout address on Eligus so I could get at least some reporting from Eligius.  The actual hash rate gain from the Cointerra was about 100 to 200 GH less on Eligius than the 1.6 TH what I was getting reported locally.  I finally switched the Cointerra over to a separate address on Eligius a few hours ago and the Eligius stats are now looking better.  1.56 TH reported on Eligius and 1.62 TH locally.  Need to build up more long term stats on Eligius of the unit by itself before I can say anything conclusive. 

Hi Babilonian -

For last 2 months,  the best price on a new rig delivered to your door has been that Antminers from Sushi or directly from Bitmain.  See group buy page.  Last price was 1.45 BTC for a unit that you can overclock to 200 Ghash an they run faithfully.

https://bitcointalk.org/index.php?topic=448425.0

http://sushi-review.com/

Sushi is a proven seller and delivers the goods.

Even at these low BTC price of 1.45 BTC for 200 GHash, it is difficult to get an ROI but that is about as good as it gets right now.  Look for Sushi to return next round with even lower prices.  Perhaps 1.2 BTC or lower per unit.

You can pick up used equipment, but I would not buy it unless you can meet or beat the Antminer value. 

Exception is maybe if you can find someone willing to part with their newer technology KNC or Cointerra machine for a good price, since they are more power efficient.  But those rigs are going to be more expensive.

Happy Hashing

Bobsag3

I would like to request a refund for my 12 shares

Order: #975   1 Unit  0.09920161 BTC
Order: #1302 4 Units 0.64326776 BTC
Order: #1393 5 Units 1.01236830 BTC
Order: #1427 2 Units 0.37142857 BTC

Total: 2.12626624 BTC

Thanks for all your hard work but I may be done with pre-orders.

PM will be sent shortly.

Refund to: 17nynX93snLu1HAwAuzjady6LCMNFcbSe3

If one of the 3 or 4 big pools was bringing some BTC out of cold storage they would not need to have a fee to get it to complete in a reasonable time.  They just need to keep putting the transaction in the next block they were solving until they solve a block.  If you are one of the big 4 pools, that is going to happen pretty soon.

You have PM, please read it.

What you are describing sounds like it efficiently detects partial collisions with your rendezvous points and then from there you may be close enough to crack it in matter of days.    You have not reduced the overall search space for cracking any random address but you have greatly increased your chances and efficiency of cracking an address mathematically close to one of your Rendezvous points.

So by definition, a so called "weak" address is one that is close to a Rendezvous point


If the entire address space is 2^N,
Let A = Log2(#Rendezvous points)
Let B = Log2(#of Addresses you can brute force in few days around any one Rendezvous point)

Then within this few day time limit, you can crack any address that falls in the "weak" space of size 2^(A+B) and cannot crack any address that falls in the "hard" space of size 2^(N-A-B)

Is that about right?  If not can you describe sizes of the weak space that you can attack.

According to other experts at the link found in my post, the correct statement is, "An amount less than the full amount of the sum of all inputs can be spent," and this nuance is very important.  According to the discussion in the link, you most often transfer less than the sum of the inputs to all of the outputs, including "change" as an output.... the remainder, (Sum inputs) - (Sum Outputs) by default becomes the transaction fee.  That was how it was explained and what I was trying to show for a single input transaction with other simplifications in the graphic.  If this interpretation of the transaction fee mechanism is incorrect I would like to know.  If if is true, where is the transaction fee in your graphical explanation?

Also, "Change addresses are not shown to the user" may be too broad a statement.  The change address may not be obvious to all but in many simple transactions both the sender and receiver can figure out the change address.

Adam Back, Inventor of  the Hash-Cash Proof-of-Work used in Bitcoin, referenced article author in the original Satoshi paper, effectively endorses Eligius as he describes its low fees.   

Let’s Talk Bitcoin Interview  http://letstalkbitcoin.com/e77-the-adam-back-interview/#.UuK0zWTTnrk

Start at minute 38:00

“….Get Block Template which is offered by the Eligius pool, which has about ten percent of hashing power and actually much lower fees than other (pools),  I always wonder why Eligius does not have a much higher portion of the network”

Adam Back, Inventor of  the Hash-Cash Proof-of-Work used in Bitcoin, referenced article author in the original Satoshi paper, effectively endorses Eligius as he describes its low fees.   

Let’s Talk Bitcoin Interview  http://letstalkbitcoin.com/e77-the-adam-back-interview/#.UuK0zWTTnrk

Start at minute 38:00

“….Get Block Template which is offered by the Eligius pool, which has about ten percent of hashing power and actually much lower fees than other (pools),  I always wonder why Eligius does not have a much higher portion of the network”

See https://bitcointalk.org/index.php?topic=422021.0 for more detail and more technically correct description.  A simplified version of the transaction looks something like this.

http://i.imgur.com/jDvoJVr.png

I know of at least one case where someone did not understand that change could go back to a different address in their own wallet, they later trashed the wallet with out a recent backup and lost access to that address and many bitcoins of change.  Understand how things work and use backups.

Solving a block = Finding a Block

Something like this

http://i.imgur.com/lrIIgZD.png