The blockchain is a list of all transactions that have occurred using the bitcoin currency. Please don't use this tag for the service named 'blockchain.info'
31
votes
5answers
11k views
Can I download the whole block chain from somewhere?
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 ...
26
votes
8answers
6k views
How anonymous are Bitcoin transactions?
I read some sources that say Bitcoin transactions are anonymous, some that say they are semi-anonymous, and some that say they are not anonymous at all. In what ways are the transactions anonymous ...
26
votes
5answers
2k views
How do I reduce the size of the block chain data on my machine?
The block chain file is getting rather large, ~500MB. Is there a way to trim it or clean up, or maybe configure it to be limited in the future? I am using the stock Bitcoin client on Ubuntu.
21
votes
1answer
1k views
What do the different .dat files contain?
What data do different Bitcoin .dat files contain? How about the other files in the same folder?
The wallet.dat file is somewhat documented and there are some ways to convert it to human-readable ...
19
votes
4answers
2k views
How do I see the IP address of a bitcoin transaction?
How do I see the IP address that someone used to send or receive bitcoins with? Is it stored in the blockchain?
18
votes
7answers
5k views
How is it possible to launder bitcoins?
Some services, such as bitcoinlaundry.com, claim that they can launder your bitcoins.
Since all bitcoin transactions are publicly logged, how is this done? Wouldn't it be possible to trace back the ...
18
votes
2answers
2k views
What is the longest blockchain fork that has been orphaned to date?
The orphaned blocks view from BlockChain.info shows a recent fork of the blockchain (starting with block 173,928) that went four blocks long before being orphaned.
Other than the controlled rewind ...
16
votes
2answers
976 views
When and how did Bitcoin start?
Exactly when was the first block mined and the first bitcoins generated? How many people knew about the project at this point? Had the project been publicly announced before the first block was mined ...
16
votes
2answers
580 views
What would happen if a portion of the Bitcoin network was separated from the rest of the network?
Yesterday I asked a question over at SuperUser, so that I could have my facts straight before asking this question. The scenario sets the basis for this question.
Regarding bitcoin, what would ...
16
votes
1answer
772 views
When was block 210000 generated and who solved it?
When was block 210000, the first block to feature halved 25BTC reward, generated and who solved it?
16
votes
1answer
341 views
What are checkpoints?
I often read that checkpoints protect the network from a 51% attack because an attacker cannot reverse transactions made before the last checkpoint.
How exactly does this checkpoint mechanism work? ...
15
votes
2answers
2k views
How many Bitcoin addresses are/have been carrying a balance?
Bitcoin addresses can be generated at will, and the theoretical limit to their number is high. Addresses are constantly being generated to receive funds or balance transactions, but they are also ...
14
votes
3answers
706 views
Bitcoin usage charts
There is a lot of data out there about BTC prices, but are there any simple charts which show how much is Bitcoin really used? Something like number of Bitcoin transactions per day/week, or daily ...
14
votes
3answers
469 views
What encourages Bitcoin miners to relay blocks?
Lets say I'm mining bitcoins, and I've just received a new block that someone else has mined. What encourages me to send that block to anyone else.
I can understand how the original miner wants to ...
13
votes
4answers
345 views
Why don't the timestamps in the block chain always increase?
The timestamps starting at block 145044 are:
145044: 2011-09-12 15:46:39
145045: 2011-09-12 16:05:07
145046: 2011-09-12 16:00:05 // ~5 minutes before prior block
145047: 2011-09-12 15:53:36 // ...
12
votes
2answers
336 views
What was the most recent change to the official client that broke block validity?
There have been suggestions that various bitcoin protocol rules (max block size, mining reward policy, etc) could be changed in the future by everybody "agreeing to update their client". The ...
12
votes
3answers
413 views
How would the Bitcoin protocol be impacted if nodes only stored the blocks they cared about?
Right now, full clients of the Bitcoin network store every block ever generated (while "thin" clients instead rely on a node which does so). This greatly increases first-time initialisation for the ...
11
votes
2answers
261 views
How does a client decide which is the longest block chain if there is a fork?
Is it only the block height or is it the effort that went into the forks? In other words: does this decision account for different difficulties?
11
votes
1answer
468 views
Is the timestamp in the genesis block relevant?
Bitcoin's genesis block contains this text published at the New York Times on January 3rd, 2009:
The Times 03/Jan/2009 Chancellor on brink of second bailout for banks
According to the Bitcoin Wiki, ...
11
votes
2answers
467 views
What happens if hash rate decreases rapidly?
Since difficulty is only adjusted every 2016 blocks, what would happen if hash rate was to decrease rapidly? Wouldn't this cause blocks to be created less frequently and also making the time until ...
11
votes
2answers
455 views
What should I do about the March 12th 2013 blockchain fork?
Reddit/r/bitcoin is flooding with news that the Bitcoin blockchain has forked, in that versions 0.7 and 0.8 are accepting different blockchains. What does this mean for the users?
11
votes
1answer
298 views
How can a non-miner store data in the block?
If I am not a miner and would like to put arbitrary data in the block chain, is there currently any method or protocol to get a miner to add it for me?
11
votes
4answers
564 views
Does the bitcoin block contain minimal transaction detail? (Is it as private as possible given the proof-of-work design?)
From http://crypto.stackexchange.com/questions/508/could-one-prevent-double-spending-in-decentralized-digital-currencies-like-bitc
"Now, the only information about the transaction that needs to be ...
10
votes
4answers
788 views
How do I safely accept bitcoins without waiting for confirmations?
Are there any arbitrators that would guarantee the bitcoin transaction such that no one has to wait ten minutes to confirm the transfer of the said bitcoins?
10
votes
2answers
179 views
Is there a limit to how much extra data can be put into blocks via scripts?
According to this answer, miners can include extra data in blocks.
Is there an upper bound to how much a miner can add? How much?
9
votes
5answers
1k views
Where are the user's bitcoins actually stored?
On the person's computer ?
On bitcoin.org ? :)
Where does that information that tells others and me how much bitcoins do I have reside (the wallet) ?
I assume it can't be on my PC because I could ...
9
votes
2answers
268 views
Does block validation get more difficult as the blockchain grows?
I just downloaded Bitcoin 0.5 and started downloading the blockchain from scratch. The process was rather fast early on but slowed down noticeably later. That could of course be related to network ...
9
votes
3answers
276 views
what happens if there are no transactions in a block?
What happens if there are no transactions in a block? Suppose there is a 10 minute time frame in the middle of the night, maybe on a holiday, and there are no transactions made. Do the miners get ...
9
votes
2answers
448 views
How do you make a Genesis block?
What is involved in creating a genesis block? What makes it different from the other blocks in the chain.
9
votes
1answer
260 views
Does the official Bitcoin version 0.8. client still download the whole blockchain?
The release notes for version 0.8 of the "Satoshi" client say
"Bloom filter" support in the network protocol for sending only relevant transactions to lightweight clients.
Is this an optional ...
9
votes
2answers
327 views
How often forks occur?
How often do forks occur in the block chain? I'm interested in the small, one block forks that happen when two miners create a block at the similar time.
9
votes
1answer
349 views
Strange transaction (block 71036)
What happened to this transaction?
Can someone explain it?
http://blockexplorer.com/t/9eHTFRi3Qq
9
votes
2answers
653 views
Is “Reclaiming Disk Space” already implemented? How effective will it be?
Some people are concerned about the scalability of Bitcoin. The blockchain already has reached nearly 1 GB to download and store, which is not exactly in the spirit of a modern thin client, especially ...
9
votes
2answers
308 views
What is the “blockchain”?
What is the blockchain? I keep hearing about other "blockchain technologies", does this mean other cryptocurrencies or what?
9
votes
1answer
101 views
What are the privacy implications of filtered blockchain downloads?
There is now "Bloom filter" support in the network protocol for sending only relevant transactions to lightweight clients.
What are the privacy implications of the bloom filter? Does it leak any ...
9
votes
3answers
1k views
Knowing a single transaction can you track down a Bitcoin user?
I have used this transaction to donate to Wikileaks. I have applied no special techniques to obsure my identity. How much information can find out about me on the blockchain. What tools would you use?
...
9
votes
1answer
121 views
One dataset for many wallets… how?
It takes a while to download and process the transaction log.
Doing that for dozens of wallets would be a big waste.
I want to run just one client full time as a log processor.
Then for each wallet, ...
9
votes
1answer
271 views
Is EFF's proposed Sovereign Key system similar to how Namecoin/Bitcoin works?
To avoid the problems caused by the current SSL certificate infrastructure, the Electronic Frontier Foundation has proposed Sovereign Keys, which appears to be backed by a distributed, append-only ...
9
votes
2answers
322 views
Have there been attempts at a Bitcoin-powered general purpose database?
https://en.bitcoin.it/wiki/Bitcoin-Powered_Database
As far I know, the Bitcoin blockchain is pretty much the only data structure that is both global and tamper-proof.
global - There is one global ...
8
votes
2answers
248 views
What is the block maturation time?
I was reading the wiki article about the blockchain and I didn't understand the part in bold:
When a block becomes an orphan block, all of its valid transactions
are re-added to the pool of ...
8
votes
2answers
398 views
why isn't there a fast block chain update inside a LAN behind a router between two bitcoin clients?
This is the scenario:
2 computers on a LAN with non real-IPs (192.168.X.X)
router forwards port 8333 only to one of them (the 2nd one).
1 computer has the full blockchain updated in its bitcoin ...
8
votes
2answers
309 views
What prevents bitcoin from breaking down in case of a “transaction attack”
Let's say that I want to kill Bitcoin by means of a transaction attack. What in the bitcoin system prevents the following approach:
I buy a limited number of bitcoin in the market.
Using a small ...
8
votes
1answer
330 views
What happens when a miner does not claim all fees/generated coins?
Suppose that a miner for some reason has the generation transaction of their blocks not take all the possible coins. This can happen for a variety of reasons, almost all of which are bugs:
An ...
8
votes
2answers
207 views
Are private keys published to the blockchain after spending coins from a wallet?
Always I spend coins the final balance of the address that is used for transaction will go to zero. The remaining coins comes back as a change to a new address. Will this indicate that the private key ...
8
votes
2answers
203 views
How can you find out what is the latest block number?
When running a fresh client, or after not being connected for a while, the client takes some time downloading new blocks. How can you find out what is the target block number (the id of the newest ...
8
votes
2answers
718 views
How can I view the current blockchain size?
How can I view the current size, preferably in bytes, of the blockchain? Is there a CLI command for bitcoind? Or a website that displays the size?
8
votes
2answers
659 views
What will happen when SHA 256 needs to be replaced?
MD5 used to be the hash algorithm. Everyone loved it, but now, not so much.
What will happen to bitcoin if flaws are found in SHA256 in the future?
7
votes
6answers
670 views
Can more than 1 block be solved per 10 mins on average (LONG TERM)?
I am wondering whether it is possible for a supercomputer to find the next 1000 blocks in a very short amount of time. Hypothetically, if a government agency concentrated a supercomputer on hashing, ...
7
votes
2answers
671 views
Are there any studies into the size of the blockchain scaling over time?
After watching some of one of the 28c3 talks, It got me thinking about just how scalable Bitcoin really is.
With the size of the blockchain currently, given the number of transactions/users, will the ...
7
votes
1answer
1k views
Has any illegal data been saved in the Block Chain?
Has any illegal data been saved in the Block Chain, such as an illegal number, or illegal prime?
