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This has been brought up hundreds of times (literally almost the first thing that everyone says after reading about bitcoin is this very thing).
The problem with this is that the inputs to the calculation have to intimately rely on the current state of the network: The previous block, the transactions waiting to be performed, etc. If we used the travelling salesman problem in some contrived situation where the "solution" of the previous block was the starting position, the transactions were each a point to be visited, etc. we'd essentially still be wasting CPU cycles, as the chances of this data corresponding to otherwise useful data is very very low. Likewise, the solution has to be extremely sensitive to the initial conditions, in that a slight variation produces a vastly different solution. This is required to detect people attempting to forge blocks. The difficulty isn't solely to limit the inflow into the system, but ALSO to cryptographically provide proof that a majority of people on the network agree that THIS set of data is the truth, and not the fallicious block that someone is trying to pass off on you.
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I can't [...] make love to my Bitcoins.
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Absolutely free PSD logos for your enjoyment! Source included. http://www.shaboopie.comAll designed by me! Donations accepted  1FRN3JPH99T9vfzqFvSCtbMUhATjpHr6YH Hey, wanna throw one together for my game development company, "Spin Works"? =) I was thinking it'd be awesome to have an ambigram, but see what you can come up with. That'd be awesome! |
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Why not just use Bitcoin Block Explorer's RSS feeds? Every address has a unique RSS feed.  TIL |
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I've lost 6 pounds and all my friends.
Every single person I know is waiting for bitcoin to dip so they can say "I told you so." i was literally begging them to get in at 7$/BTC. They all hate me now. WTF?? I am going to buy new friends when BTC=$1,535.00 (parity with gold)
If bitcoins hits that, I will die. |
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Youre reporting bitcoin to the cyber police and the consequences will never be the sane ?
DON'T WORRY GUYS, THE BLOCKCHAIN. WE CAN BACKTRACE IT! |
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I have created an algorithm that counts by one and hidden it in the block chain. As 4+4 = 8 and 2 + 2 + 2 + 2 = 8 as well, you can see that my algorithm is merely a compression technique equal to all potential numbers. As child pornography and copyright protected data are merely numbers, if you run Bitcoin you have accessed not only all known child porn ever created up to this date, but you have also accessed child porn that has not yet been created making you a futuristic time traveling pedophile as well as a serious pirate. As you also have compressed child porn that will never be created in this universe, you are a wanted pedophile through out the multiverse!!!
You're also responsible for plagarism, identity theft, credit card fraud, access to state secrets such as nuclear launch codes, reading your neighbors mail, Conspiracy and treasonous plans for mass murder, expressed intent and detailed plans to produce nuclear devices, etc. |
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Can I write it on my arm every day for a certain period of time? (A month might be unhealthy, but it's better publicity because people see it and think "... wtf is that written big and black with a sharpie on his arm?". I'll provide pictures. Haha.
lol... Sure... Post pictures Of-course you don't need to do that for a full month.  =P And you're in luck, Tomorrow is Graduation for MIT students, and so it's going to be the busiest day of the year at my work. |
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Can I write it on my arm every day for a certain period of time? (A month might be unhealthy, but it's better publicity because people see it and think "... wtf is that written big and black with a sharpie on his arm?". I'll provide pictures. Haha.
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I don't understand exactly what we mean by anonymous transaction.
If Alice and Bob want to trade some stuffs, what prevent them from using GnuPG to do both negociation and bitcoin address communication in an encrypted manner??
I know that Bob could be a police officer pretending he's just a customer, but still...
The problem is in the transfer of funds. Also, what you've described is a SECURE transaction, not an ANONYMOUS transaction. With bitcoin, you can transfer money to someone whom you have NO idea who they are (plausible deniability) etc. |
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Quote
32 merkle_root char[32] The reference to a Merkle tree collection which is a hash of all transactions related to this block
~~~~~~~~~~~~~~~~~~~~~~~What's this? where does it come from?
That ones a bit confusing and has to do with verifying all the transactions in the block more efficiently. google "merkle tree".
When mining, how to fill this field? Okay, how do we fill the tree leaves? Transactions. I don't understand the concept, we will have transactions after the block is found, right? block is used for transactions. What transaction do we have before the block found (while mining)? Blocks contain transactions. The fact that a block contains them "verifies" them. A transaction is generated by someone saying "I want to send coins." Have a look at http://blockexplorer.com/, gives some pretty useful block data. |
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Quote
32 merkle_root char[32] The reference to a Merkle tree collection which is a hash of all transactions related to this block
~~~~~~~~~~~~~~~~~~~~~~~What's this? where does it come from?
That ones a bit confusing and has to do with verifying all the transactions in the block more efficiently. google "merkle tree".
When mining, how to fill this field? Okay, how do we fill the tree leaves? Transactions. |
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Quote
32 merkle_root char[32] The reference to a Merkle tree collection which is a hash of all transactions related to this block
~~~~~~~~~~~~~~~~~~~~~~~What's this? where does it come from?
That ones a bit confusing and has to do with verifying all the transactions in the block more efficiently. google "merkle tree".
When mining, how to fill this field? |
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Heh, I wonder if it's possible to create a block without the generate transaction?
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With in a block, there are following:
what is to be hashed in the bolck and where does they come from?
4 version uint32_t Block version information, based upon the software version creating this block
~~~~~~~~~~~~~~~~~~~~~~~I think it's self generated of come from a hardcode value.
It's so that, if the code changes down the line, we don't automatically reject this one because it's slightly different and thus don't recognize it. The code can look back and say "Oh yes, for version 1, this is how blocks were done, so it's valid." 32 prev_block char[32] The hash value of the previous block this particular block references
~~~~~~~~~~~~~~~~~~~~~~~I think it's come from the Bitcoin network
This comes from your local copy of the block chain, which you in turn got from someone else on the network solving the block. 32 merkle_root char[32] The reference to a Merkle tree collection which is a hash of all transactions related to this block
~~~~~~~~~~~~~~~~~~~~~~~What's this? where does it come from?
That ones a bit confusing and has to do with verifying all the transactions in the block more efficiently. google "merkle tree". 4 timestamp uint32_t A timestamp recording when this block was created (Limited to 2106!)
~~~~~~~~~~~~~~~~~~~~~~~Is there a NTP server or come from local CMOS clock ?
It's a weird hybrid "agreed upon" time that is calculated based on what other nodes on the network are saying the time is, so everyone arrives at kind of an "average" time. 4 bits uint32_t The calculated difficulty target being used for this block
~~~~~~~~~~~~~~~~~~~~~~~I think it's come from the Bitcoin network
This comes from everyone agreeing (essentially) on what the difficulty should be because of the rate that blocks are being solved at. 4 nonce uint32_t The nonce used to generate this block… to allow variations of the header and compute different hashes
~~~~~~~~~~~~~~~~~~~~~~~What is this? where does it come from?
This is the magic number that you change in order to try and make the hash of the whole thing less than the difficulty. Essentially, you start at 0, change it to 1, 2, 3, 4, etc. until you find a valid block. 1 txn_count uint8_t Number of transaction entries, this value is always 0
~~~~~~~~~~~~~~~~~~~~~~~0
What else to be hashed when mining? and where are they come from?
How do we identify the block creator ?
Thanks
You identify the block "creator" by whoever was awarded the 50 bitcoins in the first "generation" transaction. |
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Nah, they're saying that there's no more bitcoins in the bitcoin economy. That's it folks, shows over.
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(My time is precious, if you want to make it up to me, you can point your miner at 1Mgpvj55TK6t8bSzgUabSBjUTZb6ohNVXD for half an hour or simply donate a bit and I will <3 you forever and ever ) Seeing as my miner hasn't generated any coins in the last half hour, I went back in time half an hour and changed the target address. I just changed it back right now. Happy?  =( |
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The block chain must still be downloading, or you have a different wallet in the client than contains that address. |
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If I'm not mistaken, most effort has gone into "single" SHA256, and though the composition of SHA256 operations would seem harder to crack, one never knows.
SHA256 allows an attacker to create a hash that corresponds to [your message w/padding] + [his own message] without having to know what [your message] was. This could be a serious vulnerability for some (incorrect) applications of SHA256. Double hashing prevents this attack. Really? I thought that was only on SHA1 or MD5... |
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There's ALSO always this point to consider: The reason people want to see physical bitcoin is to enable BTC payments without being online. This does not do that. If, for some reason, I bought BTC on a CD or USB stick, the first thing I'd do is load the wallet.dat in there onto a computer somewhere and transfer the coins to another address. As long as I haven't done this, the original seller is able to spend the coins at will.
Well it all depends on the emitter's intent. If you traded a private key from an individual, you should redeem asap. If you got such a thing as a bitbill, you should consider the emitter has a very low incentive in destroying a sustainable business model forever to get a 1 day lotto like hit. Yea, bitbills are good. The "put a wallet on a USB stick" is not. |
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