Maand: september 2011

How would I go about making the simplest form of a CPU bitcoin miner? I have not been able to find documentation on the whole process…

Why is 6 is the number of confirmations that is considered secure? I haven’t found any mathematical explanation or otherwise that explains why it is 6 and not 5 or 7. Is there a historical reason for 6? Is there a specific way to calculate it so 6 is just a number that was chosen?

I’m trying to implement my own Markle Tree, currently I’m working on getting the hashing done correctly.

I’ve used some hashes from http://blockexplorer.com/rawblock/000000000000a85d42610b292d2baebe54ff0c854847fe3d2ca37ac7d6e46b99

Example inputs (first two hashes from blockexplorer):

Ina: 3a459eab5f0cf8394a21e04d2ed3b2beeaa59795912e20b9c680e9db74dfb18c

Inb: be38f46f0eccba72416aed715851fd07b881ffb7928b7622847314588e06a6b7

Concatenated string (H1+H2): 3a459eab5f0cf8394a21e04d2ed3b2beeaa59795912e20b9c680e9db74dfb18cbe38f46f0eccba72416aed715851fd07b881ffb7928b7622847314588e06a6b7

Hash of concatenated string:
Ans v1: b5916d6bc34bd4157aa73c3d799a6cfcef85e0659465734362d0cebb8901e93d

Final hash of concatenated string:
Ans v2: 215f8397a3090a0bc8f4a2e98609a10d55fc7b939fa1ecf9803df20b1ee089a2

Result I got:
215f8397a3090a0bc8f4a2e98609a10d55fc7b939fa1ecf9803df20b1ee089a2

Expected result:
13a3595f2610c8e4d727130daade66c772fdec4bd2463d773fd0f85c20ced32d

Checked my calculations “manually” using http://www.fileformat.info/tool/hash.htm?hex=b5916d6bc34bd4157aa73c3d799a6cfcef85e0659465734362d0cebb8901e93d
and got the same results.

Am I doing someting wrong following this example: https://en.bitcoin.it/wiki/Protocol_specification#Merkle_Trees .
I take my input hashes, concatenate them together, and double SHA256 that string. I also tried treating the input strings as a and b, that is, first double SHA256 them, and only then join them together, but the result was also wrong. Does anyone have a step-by-step example of proper hashing of the Merkle Tree?

On that date, some erratic out-of-spread trades appeared on MtGox.

The explanation given says that accounts may have been compromised by the CosbyCoin attack on bitcointalk.org. I do not understand how this can lead to out-of-spread orders being executed.

He says the issue is resolved and proceeds to give us a speech about password security and says that we should keep trading “in confidence”.

That does not satisfy me at all.

I am curious about how to acquire a lot of bitcoins (or similarly move a lot of bitcoins) without hitting the bid/ask

I don’t care about blockexplorer, I am just curious about price discovery

are there any darkpools? could I just use an illiquid exchange and personally contact the counterparty and have them take the trade

options would be good too, this would make acquiring bitcoins at a certain strike easier as this is already a negotiation between the person on the other side of the contract

The concept of bitcoin days destroyed has been proposed as a measure of bitcoin volume. However, I don’t think the bitcoin wiki really explains the idea very well.

What is the purpose or advantage of knowing this statistical value?

Which websites have active bitcoin communities with discussion that is going on?

Every time I turn on the Bitcoin client it takes days to catch up with the block chain.

Are there alternatives to getting it trickling through the peer-to-peer network? Can I just download it somewhere? Wouldn’t this be ideal for distribution via BitTorrent?

If so, how do I import it into the Bitcoin client?

My client would still be validating this data (can it?), and it is all signed and proof-of-worked, so there is no real security problem here, is there?

Bitcoin’s genesis block contains this text published in The Times on January 3rd, 2009:

The Times 03/Jan/2009 Chancellor on brink of second bailout for banks

According to the Bitcoin Wiki, this guarantees that the block was only created after this date.

What would be the problem of using any other random quote?

It seems that when you send a bitcoin transaction, all the coins in the sending address are spent in that transaction, divided into the amount that you intended to send, and “change”, which goes back to you, but at another (newly created) receiving address.

That makes it a bit difficult to track your balance on block explorer (especially since the new receiving address does not seem to be displayed in the Bitcoin client anywhere).

Does it have it have to work like this, or is this a specific implementation detail of the client software?

Also, do you have to wait for change to be confirmed before you can spend it again?