text:
How to run bitcoin atom daemon?
I set up the bitcoin atom daemon on an Ubuntu server and I want to run it.
How can I do that?

Is simply passing the -daemon flag not working?

No it's not working am running Ubuntu 16.04

Can you provide some more detail? What happens instead, is there an error in the debug log?

I just followed the steps of installing btc atom and build it on Ubuntu . but i couldn't find any other steps related to how to configure rpc and how to run btc atom

You may miss rpcport number in configuration file.
Run nano ~/.bitcoinatom/atom.conf
Add new line rpcport=7332 for mainet or rpcport=17332 for testnet
Kill the process and restart server
Ref: https://github.com/bitcoin-atom/bitcoin-atom/wiki/Mining-Instructions

How to run it again?

And what's the other information of RPC and from where i get it? like the ip address , the rpc user, rpc password ... etc

Sometimes  stop command may not work after configuration change. Then you have to kill the process using  pkill -9 -f [process name] command. Here process name is daemon server name.

Their wiki doesn't provide much informations. You can utilize the bitcoin core wiki as reference. https://bitcoin.org/en/developer-reference#rpc-quick-reference . For rpc password and username, use any arbitrary string.

Does the configuration of btc atom goes same for BTC?
Like same RPC port ?

I checked the server and i found bitcoin.conf for bitcoin daemon which previous dev did . these are the lines in that file
server=1
rpcuser=btcuserpass
rpcpassword=btcpassworhuzehfsk
rpcallowip=127.0.0.1
rpcallowip=192.250.230.216
port=40443
server=1
deamon=1
txindex=1
prune=550
walletnotify=/usr/local/sbin/rabbitmqadmin publish routing_key=peatio.deposit.coin payload='{txid:%s, channel_key:satoshi}'

On other side the board is asking for URL+Port , RPC user and RPC password . so does it mean the information which i need is for URL and port will be like http://192.250.230.216:40443
Or something else because the ip address which is motioned on the config file is not the same ip address of the server which is running the bitcoin daemon

rpcallowip is to accept incoming rpc connections from outside the localhost. This is what u really wants?

yes i want to connect this daemon with a board on another server via rpc


text:
Generate QR code for multiple cryptocurrency addresses
I want to generate my own QR code with my main cryptocurrency addresses without using an online solution, is there maybe a command prompt way or particular piece of software I cam download for this, many thanks.
Also please move to correct section if this is in the wrong place

You could use offline JS libraries either with your browser or in your console.
Command Prompt
Requires NodeJS & NPM to be installed
npm install -g qrcode-terminal
qrcode-terminal '1SomeCryptoCurrencyAddressOrPK'
Offline in Browser
Or in your browser with an offline library
Save a copy of the raw qrcode.js file to your computer as a javascript file. https://raw.githubusercontent.com/davidshimjs/qrcodejs/master/qrcode.js
Then simply use it within an html file

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sort: votes


text:
Can one wallet support many descriptors?
Say I wanted to handle many different complex spending scripts in my wallet using descriptors, is that be possible?

What wallet software are you using? It depends on whether your wallet software supports multiple descriptors.

Goddamit, I meant support.
No wallet software at the moment, just hypothetical.
The idea is I want a one wallet with 3-5 descriptor and same wallet to have complex spending condition to for say inheritance and also another condition to stake my btc in these new staking chains (coreDao)

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text:
How can I determine the reason for a failed routing on c-lightning
I am running a c-lightning node (v0.8.2). I am routing a payment every few days. However, I realized that dozens of payments every day fail, many of them fail locally (I see the status 'local_failed' on RTL). Apparently, this is due to insufficient funds in the channel that was tried to route out. I tried to figure out how I can become a better hub and accommodate more of those of those payments.
My investigations where not really prosperous, as I could not determine the next channel that caused the payment to fail. I tried to inspect the logs with lightning-cli listforwards. But it does not list the out_channel.
Any ideas or recommendations how I can improve my job as a router, i.e. finding out which channels to improve / balance?
Kind regards

I believe if you c-lightning implementation does not tell you the out_channel it means that onion was sent to you. The local failure can be explained by you not knowing the payment hash. Most likely people send out onions with random payment hashes so that they can probe other peoples channels. You can set log level debug and check your logfile to confirm if it was missing preimages.
In general you cannot expect to successfully settle every forwarding. Even if you have been able to forward it there might be remote errors. In order to increase your reliability as a routing node you can do two thinks.

make sure that your channels have enough balance on either side so that they can support incoming or outgoing payments
activate JIT routing. In case your node cannot forward a payment along a channel it will not send an error back but try to rebalance your channels to provide yourself liquidity on the requested channel

Both options will probably cost you money to begin with and remember: even if - with these measures - you have been able to forward the payment it does not mean that you get paid because the next hops could yield local errors


text:
Checking external bitcoin address balances via JSON-RPC API
I'm using bitcoin core json-rpc api in python and am wondering why...
getreceivedbyaddress()

...doesn't allow me to specify an address that isn't in my local wallet?
The whole blockchain is open, I can search anyone's address/balance via a web browser, so why would the API prevent me checking?
Is there another method for doing this that I'm missing?

Bitcoin Core does not track each individual address, only the addresses associated with your wallet.
There are other clients, such as bitcore-insight and btcd, which maintain a separate address index.
Alternatively, you can implement an index yourself, or run an existing one such as ElectrumX.


text:
Security advise on setting up a gambling Bitcoin site
I have written a Bitcoin gambling site and am planning on the best approach to host it/manage it securely.
The site is implemented in Java using the BitcoinJ API and servlets etc are handled via the Play framework.
Here is an overview of what the site does at high level:

Communicates to a datastore where "receive/return addresses" inputed by user are stored.
Creates a unique receive address for the user (also stores this).
Stores the answers chosen by user.
Checks for verified transactions and updates datastore with this info.

Finally, when the app has a return address to send winnings to and confirmed verified and confirmed winner, the winnings are sent out.
I am thinking about how to best host this application. Would the best way be to proceed to purchase a dedicated server and run the whole app on there? Are there better/more secure ways that this can be done (also cheaper methods i.e. shared hosting?).
Thanks for your help!
EDIT
Potential alternative option:

Lightweight app on web which communicates directly to a database.
Database holds a big list of readily created "receive addresses" by a wallet held off server.
Off server process runs on my PC continuously checking the database for "work".

This approach is probably a lot safer and would also remove the need for a dedicated server. The downsides would be having to run a PC 24-7 at home which constantly checks for work.
The off server process would create more addresses when needed and add them to the database (remotely). It would also send out bitcoins to winners and transfer the bulk of BTC to an offline wallet.

Using Bitcoin means using maximum security
You can cut corners but you need to understand that by doing so you are introducing risk into your business model. These risks include, but are not limited to:

private key theft by malicious administrators
cracks through known vulnerabilities in virtual machine implementations
cracks through weak operating systems (use a secure Linux distro)
theft or confiscation of hardware (data centers may take your stuff)
domain name seizure (ICANN can and will)

To reduce the risk involved you need to isolate your Bitcoin code from your public-facing web code as much as possible. This usually means having your own dedicated hardware under your physical control. Often this means a machine in your basement with a dedicated VPN and static IP address.
Make sure that only the "float" part of your balance is accessible to the server in a hot wallet. The rest should be in an offline cold wallet requiring manual access to free up the funds.
Remember: Bitcoin is money. Take the same precautions that you think a casino would take then go the extra mile.

Hi Gary, thank you for your answer! I have added an alternative approach to the original post that could be better. What do you think?

That alternative (work queue scanner) is a better approach. Your main worries are protecting the private keys and detecting false transactions (compromised server sending/receiving false instructions). Having a supply of pre-generated addresses is a good solution to avoid private keys on the server. When rendering the public addresses ensure no third-party JavaScript is running that could overwrite the values in the DOM. Be paranoid.

To protect your webapp/bitcoin in first place think like an attacker.
Then do what if scenarios, what happens if an attacker gains access to the webserver, database, or whatever??
Don’t put all eggs in one basket.
Guess the most vulnerable parts of the whole venture might be webapps/frontends, userfail and finally exploitation on outdated software.
Maybe you want to have a look into IDS solutions.

For example have a SNORT instance in-between (maybe through a VPN construction). (running heavy IDS on the main server is a bad idea, maybe).

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text:
Are there projects visualizing and analyzing historical transaction data?
I know blockchain.info etc, but I'm looking for things beyond simple timelines of transaction volume and the like. I was thinking towards scientific projects that aim at discovering patterns in the historical data, for instance:

are there addresses that accumulate large amounts of btc?
are there interesting transaction pattern, e. g. prolonged transaction "ping pong" between address pairs, "star patterns" where a single address sends out transactions to a large group of others, etc
are there amounts that seem to get passed on along a long chain of addresses?

Note that those are just examples I made up to illustrate what kind of angle I'm looking for: a more open-ended, scientific analysis rather than trading advice. That same notion makes it hard to search for projects, so I'm hoping that someone might happen to know something.

I rewrote the question in the hope to make it more answerable.

Check this website. It has summary of the tools available http://block-chain-analysis.com/

Your problem is the "things like that".  There are lots of different things that might be of interest to some people and not to others, and so each site has a few reports or charts but none are comprehensive.
Two examples: blockchain.info has a number of reports in the bottom right of their main page under the 'Other Bitcoin links' that has some reports that some might find interesting.  Bconomy has a number of charts that provide information about blocks and transactions.

I understand. I rewrote the question hoping to be more specific this time.

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text:
(How) can I run standard clients on a "toy" block chain?
Say I build some software around the Bitcoin system and I would like to try stuff without having to earn real BTC first, and without having to employ a lot of hashing power to grow the block chain.
As I understand it, the bitcoin clients connect to the network to get the authoritative block chain, so it seems I can't set up a toy network easily. Or can I? I would assume developers of the clients would need some way of testing their software.
While I am a software developer, and familiar with stuff like modifying source and rebuilding the client, the point of this exercise would be to run unaltered clients in a dummy environment.

This seemed to be a newbie question. There is what is called a "testnet", and there is more info on the Wiki at: https://en.bitcoin.it/wiki/Testnet
This site has a specific tag for it, as well: https://bitcoin.stackexchange.com/questions/tagged/testnet


text:
Bitcoin-QT wallet.dat prior to adding passphrase
On almost any Bitcoin-QT tutorial I notice people recommending to:
(step 1) back up your wallet.dat before adding a passphrase.
(step 2) Add a passphrase and copy your new wallet.dat to a USB ....
(step 3) Write down on a piece of paper the used passphrase .
Isn't (step 1) problematic?
Say I copied wallet.dat prior to adding a passphrase and just dumped it somewhere on my computer or god forbid on a USB and the USB gets lost or computer is hacked,  wouldn't an obtained wallet.dat prior to adding a passphrase, will grant access to the new (and thought to be passphrase secured) wallet?

Where did you read this?


text:
What does "peer sent transaction already received" mean?
This is  my output from p2pool.
2013-07-10 16:06:29.543000 P2Pool: 17383 shares in chain (17388 verified/17388 total) Peers: 11 (5 incoming)
2013-07-10 16:06:29.544000  Local: 0H/s in last 0.0 seconds Local dead on arrival: ??? Expected time to share: ???
2013-07-10 16:06:29.544000  Shares: 0 (0 orphan, 0 dead) Stale rate: ??? Efficiency: ??? Current payout: 0.0000 BTC
2013-07-10 16:06:29.544000  Pool: 1074GH/s Stale rate: 17.1% Expected time to block: 23.7 hours

Problem - Why are there '???'s replacing all the values?
Question 1 - What does the 'Peers: 11 (5 incoming)' mean
Question 2 - What does the following line mean? It shows up a lot with different strings of numbers and letters:
2013-07-10 16:10:01.362000 Peer sent entire transaction 59900f72264267f0fbff2041ea50d9b72ba44448aa2244429e855f5372ba2bca that was already received

Thank you for your time.

The "???"s mean that P2Pool has no estimate because nobody is mining on this node. "Peer sent entire transaction ..." is printed when a little bandwidth is wasted because peers are forwarding transactions needlessly.


text:
why multibit doesn't show my BTC
version is newest 0.5.12, 0 . I'v send to my multibit some BTC, then I waited for a very long time and it still shows unconfirmed, on blockchain.info shows transaction was finished, so I pressed the button "reset blockchain and transaction", then balance became zero, I waited 6 houres and it's still zero, how long will the sync take?!
in the message said"Synchronised with network." , means sync finished? but balance is still zero?!

Please man, follow up your question.

You seem to know your stuff about Multibit and I have posted this http://bitcoin.stackexchange.com/questions/18059/my-multibit-wallet-ver-0-5-15-shows-nothing-after-being-sent-part-of-a-coin if you could take a quick look at it please? From the link I posted within my question, should my Multibit wallet show the amout sent to it? Thanks a million!!!

It sounds like you are trying the right approach.
There is a support note here:
https://multibit.org/en/help/v0.5/help_support_sentBitcoinToMultibitButTheyNeverArrived.html
You can try it again safely.
Check all the details like the address is what you expect etc.
edit: And if that fails, you might want to try:
1) Exporting the private key (unencrypted)
2) Importing it into a blockchain.info wallet you create. You should then gain access your bitcoin.
If you do have to resort to exporting the private key please post that that is what you have done. (I am the lead dev for MultiBit so would want to follow up on it with you).


text:
Why is 'p2pkh:' prepended at the beginning of private key addresses in electrum?
I recently started a Blockchain course and came across the electrum software. While going through the list of wallet addresses and associated private keys I found that  'p2pkh' is placed at the start of every private key, why is that?

A single private key can lead to different addresses, depending on the script it is used in - These include p2pkh, p2wpkh, p2sh-p2wpkh.
Electrum prepends the script type to the private key during export and import so that it knows which address to derive and check for outputs on.


text:
Can bitcoind and btcd share a datadir?
I've already fully synced the blockchain with btcd, can I point bitcoind at the same datadir and use its contents?

No, they’re completely incompatible.

You can't use the same datadir, but you can tell btcd to connect to your locally-running bitcoind instance in order to do the initial blockchain sync. This means that you'll end up with two copies of the blockchain (one for bitcoind and one for btcd) but the sync will happen much faster than starting btcd with default settings.
In your btcd.conf file:
; only connect to locally-running node
connect=127.0.0.1

; no need to query for other nodes
nodnsseed=1

; listen on a port other than the default (if bitcoind is already running on the default)
listen=127.0.0.1:8336

; secure the RPC API so that you can interface with your sycing node by using btcctl
rpcuser=<rpcusername>
rpcpassword=<rpcuserpassword>

; sync with indexes enabled
txindex=1
addrindex=1

Now start btcd. It should start, but no peers will be connected - you can verify this by running btcctl getpeerinfo and you'll get [].
With btcd running, force your bitcoind node to connect to it by using the command bitcoin-cli --rpcuser=<bitcoindrpcusername> --rpcpassword=<bitcoindrpcuserpassword> addnode 127.0.0.1:8336 'onetry'
Now run btcctl getpeerinfo again, and you should see that your local bitcoind node is connected. btcd has started to sync and it should only take a few hours to sync from the local node. This is much faster than the days it would take to sync over the internet.


text:
Bitcoincore listrecievedbyaddress doesn’t work
I am trying to run bitcoin full node on testnet. I have downloaded ant started bitcoind with such config:
testnet=1
regtest=0
server=1
listen=0

I'v generated new address tb1qklst9t8rk97zmwqdq4t8s3dazk3h6rps20y32d
with "getnewaddress" command.
I`v made the transaction from Electrum testnet wallet to this address (transaction id: cefe1ca9048f2fcd42c40b1060cdf4183f98f24eca95a9c499006ee39a033d54).
I can see this transaction in Electrum testnet wallet or on tbtc.bitaps.com.
But results of commands "listreceivedbyaddress 0 true true" and "gettransaction cefe1ca9048f2fcd42c40b1060cdf4183f98f24eca95a9c499006ee39a033d54" are:
[
  {
    "address": "tb1qklst9t8rk97zmwqdq4t8s3dazk3h6rps20y32d",
    "amount": 0.00000000,
    "confirmations": 0,
    "label": "",
    "txids": [
    ]
  }
]

and
error code: -5
error message:
Invalid or non-wallet transaction id

The result of "getblockchaininfo" is:
{
  "chain": "test",
  "blocks": 626786,
  "headers": 1774117,
  "bestblockhash": "0000000000007d5ba9c09c8ddfa2cc31195aea3fc6e351969bc6fe454d2c29b8",
  "difficulty": 65536,
  "mediantime": 1450388529,
  "verificationprogress": 0.4003797270985711,
  "initialblockdownload": true,
  "chainwork": "000000000000000000000000000000000000000000000007049211b48a78f895",
  "size_on_disk": 4446006159,
  "pruned": false,
  "softforks": {
    "bip34": {
      "type": "buried",
      "active": true,
      "height": 21111
    },
    "bip66": {
      "type": "buried",
      "active": true,
      "height": 330776
    },
    "bip65": {
      "type": "buried",
      "active": true,
      "height": 581885
    },
    "csv": {
      "type": "buried",
      "active": false,
      "height": 770112
    },
    "segwit": {
      "type": "buried",
      "active": false,
      "height": 834624
    }
  },
  "warnings": ""
}

Bitcoin core version is 0.20.0.
What is wrong?

Your transaction was mined in block 1773944.
Your node has only synced up to block 626786.
Once your node has synced block 1773944, you should be able to see the transaction.


text:
How to Avoid Wallets Compromised by Android Vulnerability
I'm interested in understanding Bitcoin better, and developing good habits with regard to cryptocurrency, even though I'm not using Bitcoin very much at the moment.
But based on my very limited activity with Bitcoin, I think I've found myself in a vulnerable position through mechanisms that I don't understand. Here's what I've done:

Months ago, I set up Bitcoin Wallet on my Android phone. And it, of course, assigned me a Bitcoin address (1L...).
I visited a couple of those sites where you view an advertisement and get a trivial amount of Bitcoin, just to see how the transactions flowed. This worked, and I then had Bitcoin holdings that were too small to spend. I left it all alone for a while.
I installed Multibit on my desktop and imported my private keys from Bitcoin Wallet.
Bitcoin Wallet posted a notice of an Android vulnerability that affected Bitcoin wallets, and suggested moving funds to a new address. The app created a new address for me (1M...). I imported the new private keys to Multibit, but my holdings were of course too small to be moveable.
Recently I saw that an app developer who makes a free app that I find highly useful was taking tips in Bitcoin. I thought this would be a nice chance to go a little deeper into the Bitcoin ecosystem. So I purchased enough to cover my tip (with a little left over) from Coinbase, and then transferred them to my new, presumably uncompromised, address: 1M...
I initiated my tip to the app developer in Multibit. That transfer went successfully, but when I examine the blockchain, I see that the transaction has emptied my new address (1M...) and put it all in the old address (1L...) that Bitcoin Wallet warned me not to use any more.

The amounts I'm dealing with are quite small, so I'm not in a panic about it -- but I don't understand what happened here. Specifically,

Why did the transaction clear out the funding address rather than just take what it needed from it?
Did I do something wrong? Or, alternately, is there something I could/should have done to manage the transactions with more detail?

As this bug has been fixed the best idea is to archive those addresses which have been generated before the update (not all wallet applications support this feature). The other is to completely remove the wallet and replace with a new updated version.
As far as im aware no wallet supports deletion of addresses (for obvious reasons).
As for creating transactions, on specific wallets some have more detailed sending abilities than others, its all about a balance of userfriendly vs features. If you look at blockchain.info wallet it has advanced features allowing specific send from and change addresses to be set, most mobile apps will probabaly lack such sophistcation due to being made for mobile.


text:
How do I validate the correctness of a bitcoin multisig address?
Normally when validating a bitcoin address I Base58 decode the string, validate the checksum, throw away the checksum, and end up with 21 bytes. Then I verify that the address is fr the correct network:
If the first byte is 0x00 I have an address for the production network
If the first byte is 0x6F I have an address for the test network
For this multisig address 2N5vbPQB7pMqyVa8JRcpZdCQLQCwDZCMyfo I get 0xC4 as the first byte.
Does this mean that 0xC4 is the prefix for all multisig addresses on the production network?
In that case, what is the prefix for the test network?

Multisig addresses are defined as follows:
base58(0x05 + [20-byte scripthash] + [4-byte checksum])
For testnet, it's 0xC4 instead of 0x05, indeed.


text:
What does message "Server is lagging (9 blocks)" mean in Electrum?
When opening Electrum, the bottom of the window showed message "Server is lagging (9 blocks)".
What does this mean? Is the Electrum server not up to date with the blockchain? Can I expect the problem to resolve itself quickly?

The message informs you that the Electrum server your wallet client is connected to is not in sync (not up-to-date) with the blockchain. In the message you quote it is 9 blocks behind.
This can happen when a server has been rebooted after maintenance or, in some cases, if the server is malfunctioning. Hence, there is no guarantee that the problem will resolve quickly.
While the server is lagging the blockchain, it is unable to provide your connected wallet with an accurate transaction history.
By default, Electrum connects to a random Electrum server on the network. To connect to another server simply exit and restart your wallet, or you can go to Tools > Network and manually specify a preferred server.


text:
Are change addresses visible from the GUI in the Bitcoin-QT client?
I've seen this question pop up on reddit multiple times, and I don't know the answer.
However, I do know that in my own wallet, several unlabelled addresses have appeared over time without me requesting for them to be created. Are these be the change addresses used when I spend bitcoins, or are the change addresses invisible from the GUI?

Change addresses should be invisible from the wallet GUI.

However, there is a pull request which would enable that feature: https://github.com/bitcoin/bitcoin/pull/2343

However, I do know that in my own wallet, several unlabelled addresses
  have appeared over time without me requesting for them to be created.

Could you provide a bit more clarity on where these addresses have appeared? In Wallet.dat after using PyWallet or in the receive coins gui?
Bitcoin-Qt uses a regenerating key pool of a 100 pregenerated keys mechanism to handle change
https://en.bitcoin.it/wiki/Key_pool
and to read Satoshi's words:
https://bitcointalk.org/index.php?topic=1414.0

Are these be the change addresses used when I spend bitcoins, or are
  the change addresses invisible from the GUI?

My understanding is that all change addresses should be invisible in the normal GUI. The only way you should be able to see them is if you open wallet.dat.
I hope this helps.
Edit:
I spoke with Wladimir here is his reponse:

That indeed sounds weird.
The old UI (wxbitcoin) used to generate new, unlabaled addresses in
  some circumstances. With Bitcoin-Qt this should not be happening.
The wallet starts with one receiving address, and all receiving
  addresses after that should be manually created. If receiving
  addresses still appear out of the blue with 0.8.x this is a (minor)
  bug. To be able to fix it I need a way to reproduce it.

Could you take some screenshots and also forward me your hardware configuration. I'll send it to him and hopefully we can try to reproduce it on his end.

The addresses appeared in the GUI list of receiving address, with no description against them. I've run several versions of the client over time starting from something like 0.3, and as far as I'm aware new addresses have continued to appear in the list occasionally up to at least version 0.7 There's about 10 there now that I didn't create, and I've re-labelled several more for use too. Thanks for your answer!

You know I've been working with Wladimir J. van der Laan on my course. I will forward your question to him. If he can't answer it, then no one can. https://bitcointalk.org/index.php?topic=185185.0


text:
Is the cryptocurrency Bitcoin a good idea?
http://www.quora.com/Bitcoin/Is-the-cryptocurrency-Bitcoin-a-good-idea/answer/Adam-Cohen-2
As someone who studied Economics before Computer Science, to me this answer raises some very valid points. In order to be widely adopted, Bitcoin needs to have the unconditional trust of the people. Is Adam Cohen right?

This will likely get closed because it is too broad to answer. Maybe you should try to make a more specific question? This is Q&A, not a discussion site.

Perhaps rephrase this as "Does Bitcoin have a chance to succeed? How exactly?"

Adam Cohen is wrong.
Seeding Initial Wealth: If you're jealous of the early adopters, become one. If we assume Bitcoins fail, who cares who adopts when? If they succeed, then it's still early. As for mining being random or useless, no, miners are paid for securing transactions. The way Bitcoins work, seeding initial wealth is a side-effect of the distributed transaction resolution system.
Built In Deflation: He repeats the idea that the set of early adopters is fixed. If Bitcoins last long enough for the deflation to happen, you can still be an early adopter since it's still very early. (And they actually won't deflate because the money supply will be inflated by things like fractional reserves, mortgages, and the like just like other currencies are.)
Lack of Convertibility: I don't think a currency has to be able to act as a store of value. In fact, use as a store of value to some extent conflicts with use as a means of exchange. But in any event, Bitcoins are already reasonably convertible and as they become more popular, exchanges will increase as well.
When Something Goes Wrong, It Will Die: Serious things have gone wrong with Bitcoins, including an exploited bug that let people create Bitcoins out of thin air. What happened? Everyone who cared about Bitcoins pulled together to fix the problem. But if you're really worried about this, the fix is simple -- don't use Bitcoins as a store of value, just use them as a means of exchange.


text:
Unstuck a unconfirmed transaction with Coinomi
I sent a Bitcoin transaction with Coinomi android wallet. I selected the default recommended fee option. However, later I saw that it set only 0.01 USD transaction fee. My transaction is stuck in an unconfirmed state. I need the transaction to go through, it's lot of Bitcoins and I need them now. What is a step by step guide to either cancel the transaction or make it through? The address I'm using is BIP 84 Native Segwit. I tried uninstalling and reinstalling Coinomi, but that doesn't change anything after I re-enter the master seed. I didn't have luck with other wallets either. I read about double spending, but I'm not sure how to execute it. Any help?

Does this answer your question? Why is my transaction not getting confirmed and what can I do about it?

It's generally not possible to cancel BTC transactions after they are broadcast to the network. If the transaction is valid, it can be held by miners until it's economically interesting for them to confirm the transaction (until there are no other transactions paying higher fees).
When you say "double spending", you are probably referring to a technique called "Child pays for parent" (CPFP). This involves making a new transaction spending the leftover change of the original transaction, but using a high fee. Miners can only confirm the child transaction after confirming the parent. By using high fees for the former, miners will be more incentivized into confirming the latter.
To do this in Coinomi, first check the original transaction on the block explorer. Unless you sent your full balance, you should see 2 destination addresses. One is the real destination, the other is your change. Take note of the change address (if there is no change, you can't do CPFP). Second, open your BTC wallet in Coinomi and at the top right corner of the screen select "... / Show unspent outputs". From the outputs list, select all addresses that are not your change address from the transaction and set them as "do not spend". Back to the BTC wallet in Coinomi, copy your own receive address, and make a transaction sending your full balance to it. Set "high" priority fees, or custom set a fee even higher than that if the transaction is urgent. After the new transaction confirms, reset your outputs back to spendable.
PS: Replace by fee (RBF) is a feature that allows increasing the fees of unconfirmed transactions without making a completely new transaction, and will be available in a future update.
PS2: you can contact support directly via support.coinomi.com


text:
How should centralized wallets handle user accounts?
I tried to generalize this question from one I asked on the BitcoinJ development list.
I'm working on a project that requires a centralized wallet. From what I gather, these types of services generally rely upon simple balance checks to ensure that an individual user doesn't spend more than is in their wallet. That is, all users share a pool of keys, and the only thing tracking each user's balance is the service's database.
The Bitcoin daemon exposes functionality not in the GUI, namely that of accounts. An account is a string that groups keys. You can send from an account, and it will only gather coins owned by the keys in that account. This is beneficial, but is fairly limited. Using this however, you could have each account be a unique identifier for a user, and then that user "owns" the associated keys. One seeming drawback to this is that there is one centralized location to change ownership of an account.
I came up with a potentially better solution. Each account "owns" one or more public key hashes (the meat of a Bitcoin address). When creating a transaction, the service will transmit these hashes, letting the wallet know that when scanning unspent outputs, only use those with a public key hash owned by the user. In this way, without associating a user account with the private key itself, we are able to allow the user to have exclusive access to any number of keys.
Does this seem like a good solution to the problem? Is there something better that I'm missing?

Your question contains a false assumption. When you send from an account, that just sets which account's balance is debited. The client does not think of specific coins as being owned by accounts.

In this way, without associating a user account with the private key itself, we are able to allow the user to have exclusive access to any number of keys.

A very significant benefit that wallet services can offer is immediate and invisible transfer of coins between their accounts, by just updating their internal databases, without going through the block chain. This is how you can facilitate trades on MtGox for example, and it also provides increased anonymity, because you can now make transactions that are not visible on the block chain (and the transactions that are visible are withdrawal and deposits into the service as a whole, and those addresses are shared between many users, so also effectively anonymized). Obviously, this will not work unless the service can "redistribute" all the coins in all its addresses at will internally. (And obviously this also only works if every account holder trusts the wallet service to not take all the coins and make a run for it).

Each account "owns" one or more public key hashes (the meat of a Bitcoin address).

Actually, for making deposits, this is how it already works with wallet services. There is a (or many) receiving address (sometimes for one-time use, sometimes stable and fit for publication) that is associated with every account holder. You deposit to the account using that address. However, the private key remains with the wallet service, and can be used by it for all kinds of unrelated payments.

Exactly.  If one is going to implement a central wallet then use a central wallet and manage client balances "out of band".  The system explained in the question seems to have all of the disadvantages of a central wallet and none of the advantages.


text:
What are the perceived advantages that bitcoin has over other currencies or other ways of sending money?

Possible Duplicate:
What are the perceived advantages of bitcoin as a means of exchange?

Suppose that the value of Bitcoin in USD magically remained constant from this day forward. What unique advantages does Bitcoin has other its alternatives (e.g. USD, Paypal)


text:
Where is the post where the original Bitcoin Whitepaper was first released?

Possible Duplicate:
When and how did Bitcoin start?

I understand Satoshi release the original whitepaper to some cryptography mailing list, in 2009 I believe. Can anyone point me to that thread?
It would be interesting to see the first responses the whitepaper received.

That's covered in this question: When and how did Bitcoin start? so I'll close this one. The link is in the accepted answer.

@D.H. - actually, the correct link wasn't in the accepted answer, but I managed to find it nonetheless via by digging from there - updated the accepted answer with the link.

Oh, sorry about that, I confused the announcement of the design paper with the announcement of the first release. Thanks for updating the answer.


text:
Are there statistics on how Bitcoin holdings are spread among addresses?
I'm aware an address can belong to multiple people, and one person can have multiple addresses. Still, I'd like to assume the number of accounts per person is O(1) on average.
Are there statistics on how much the bitcoin holdings are spread between different addresses - in other words, on whether a few addresses hold a large portion of the bitcoins, or rather is it spreading out slowly?
Ideally I'd like to see a graph of this "measure of spread" over time.
Related Questions
Is it possible to estimate the Gini coefficient for Bitcoins and if the trend is increasing or decreasing?

Assuming the number of accounts per person is 1 on average is not enough. If there's one guy who holds 10 Bitcoins but has 100 accounts and 100 rich guys who consolidate all their Bitcoins into one Mt. Gox account, that's one account per person on average. But it still renders looking at Bitcoin account holdings to determine spread/concentration meaningless. You need a lot more assumptions and many of those are much more questionable.

What do you mean by accounts? Are you only talking about exchanges?

@David - Even if this is questionable, I'd like to see where it leads.

@nmat - accounts = wallets?

I don't know if any of this data is of any use or significance, but...
I calculated the Gini coefficient at the end of each month of Bitcoin's history.  I did it in two different ways:

The vast majority of Bitcoin addresses that have ever been used are now empty.  They don't represent the "have nots", they're just addresses that have been used and discarded, and so shouldn't be included in the calculation.  Similarly there will be lots of addresses which are holding change from transactions.  I arbitrarily decided to throw away all addresses with a balance of less than 1 BTC for this first calculation.
Then I calculated the Gini coefficient for just the 100 richest accounts at the end of each month.

The results are shown below, with the columns in order:

the date.  "Jan 09" means "the end of Jan 09"
the total number of addresses in existence at that date, including empty ones
the number of addresses with 1 BTC or more in them
the amount in the richest account
the amount in the 100th richest account (notice how this stayed at 50.00 for over a year)
the Gini coefficient of the >= 1BTC addresses
the Gini coefficient of the top 100 addresses

-date-   addresses    >1 BTC   1st - 100th richest   Gini >1   Gini100
Jan 09       2,569     2,439     2775.00 -   50.00   0.04571   0.50862
Feb 09       5,975     5,642     9075.00 -   50.00   0.05064   0.71354
Mar 09       9,444     8,864    16675.33 -   50.00   0.05794   0.82048
Apr 09      12,893    12,120    21175.33 -   50.00   0.05715   0.85527
May 09      16,288    15,380    26675.33 -   50.00   0.05306   0.87075
Jun 09      18,528    17,534    30675.33 -   50.00   0.05118   0.87980
Jul 09      20,456    19,338    36675.33 -   50.00   0.05248   0.89165
Aug 09      22,021    20,741    44473.86 -   50.00   0.05617   0.90351
Sep 09      24,180    22,639    53974.86 -   50.00   0.06188   0.91664
Oct 09      26,311    24,366    61424.62 -   50.00   0.07208   0.92725
Nov 09      28,533    26,403    61424.62 -   50.00   0.07279   0.93164
Dec 09      32,611    29,818    61424.62 -   50.00   0.08352   0.92241

-date-   addresses    >1 BTC   1st - 100th richest   Gini >1   Gini100
Jan 10      37,647    34,333    72374.36 -   50.00   0.08571   0.92339
Feb 10      43,329    37,262    72374.36 -   50.00   0.13683   0.88570
Mar 10      48,615    40,316    72374.36 -   50.10   0.16674   0.82492
Apr 10      57,806    42,661    72374.36 -  500.00   0.21059   0.71037
May 10      63,368    44,583    72374.36 -  630.00   0.24448   0.65747
Jun 10      69,540    46,963    72374.36 -  750.00   0.26638   0.62843
Jul 10      94,992    51,628    72374.36 - 1757.14   0.32583   0.56689
Aug 10     107,172    53,578    72374.36 - 2100.02   0.35365   0.52483
Sep 10     120,562    53,492    72374.36 - 3000.00   0.39915   0.46956
Oct 10     135,952    54,637    85000.00 - 3333.33   0.42841   0.46050
Nov 10     155,639    55,756    90000.00 - 4150.00   0.45464   0.43790
Dec 10     176,326    57,247    90000.00 - 5000.00   0.47592   0.38625

-date-   addresses    >1 BTC   1st - 100th richest   Gini >1   Gini100
Jan 11     210,243    58,073   250000.00 - 5350.00   0.49987   0.47440
Feb 11     267,542    59,699   250000.00 - 5650.51   0.52439   0.47584
Mar 11     353,093    61,984   250000.01 - 5613.86   0.54646   0.45504
Apr 11     443,112    64,254   200000.00 - 6002.81   0.57161   0.46808
May 11     631,480    70,883   297000.00 - 6309.40   0.62830   0.49247
Jun 11   1,061,590    90,159   424242.42 - 6308.24   0.70803   0.52602
Jul 11   1,548,806   101,895   384587.42 - 6450.00   0.73473   0.50905
Aug 11   1,930,979   105,572   104895.01 - 7495.92   0.74448   0.41533
Sep 11   2,205,926   106,973   105000.00 - 6926.85   0.74847   0.45014
Oct 11   2,411,298   110,463   105000.00 - 7345.73   0.75422   0.44981
Nov 11   2,601,999   111,386   455501.30 - 6926.85   0.76065   0.51328
Dec 11   2,768,500   118,263   105555.00 - 6705.00   0.76137   0.41685

-date-   addresses    >1 BTC   1st - 100th richest   Gini >1   Gini100
Jan 12   2,956,869   123,003   105555.00 - 7000.00   0.76883   0.42408

There is TOP 100 rich list, but you have to take it with a grain of salt because:

many holders have their money spread over multiple addresses
I believe many of TOP 100 belong to MtGox account holders

If you want extended list, you could probably contact the author of that list or ask a programmer to build it. Should't be too hard to do.

Those are top 100 addresses however any individual can have anywhere from 1 to n addresses. 1 person =/= 1 address, 1 wallet =/= 1 address.  Bitcoin has no concept of an "account".

Agree, I also said something similar in my answer, probably didn't emphasize it enough.

MTGox account holders? Hmm... did you mean "accounts used by MtGox"? It has sense if MTGox stores the large amounts of coins they handle in a few addresses (and keep accountability of users in a database), because it's known they handle LOTS of coins. Not necessarily a Bitcoin-rich person stores his money in MtGox. So I believe the top-100 accounts hold money that belong to exchange users, whichever the exchange is

There is no such concept as an "account" or "wallet" in the Bitcoin network.  The Bitcoin network only records addresses.  Some clients organize one or more addresses into an account and one or more accounts into a wallet however this structure is "client side" and the network/protocol is unaware of it.  Not all clients use this type of organization.
If you are talking about addresses.  Sure you can see which addresses have the most value and how many addresses exist with some value but that isn't easily correlated to a specific entity.  As an example, my wallet currently has >200 unspent outputs in >100 addresses.  There are also about 400 used addresses which contain no unspent outputs (0 value).  An individual's coins are unlikely to be all stored in a single address even if they are stored in a single wallet unless they make a conscious decision to do so (i.e. offline paper wallet).


text:
Bitcoin Client API-RPC: Efficient way to list transactions from a list of addresses
In the API CallList:
https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list
You can pass an address as a parameter to "listtransactions" to get the latest list of transactions from an address. What if I would like to get the most recent 25 transactions from a list of 20 addresses. Does this mean I have to make the "listtransactions" call 20 times and then sort the end results?
Calling the API endpoint 20 times is fine, my problem is that if we needed to do pagination that will become very unmanageable very quickly, because it is really hard to determine what is transactions 26-50 from 20 different addresses
Thank you
EDIT:
I found that BlockchainInfo offers a very convenient endpoint for this:
https://blockchain.info/api/blockchain_api
Endpoint: http://blockchain.info/multiaddr?active=$address|$address (Multiple addresses divided by |)
However, this only returns "txs":[--Latest 50 Transactions--]
and, this does not allow you to do an offset (for example, to get transaction 51-100)

If you found an answer to your question please post it as an answer. Only use edits to clarify your question.

@StéphaneGimenez, thanks for the notice. Although, I didn't find an answer to my question. I found a partial solution that does not address my needs.

The most efficient way to get a list of transactions from multiple addresses is to store every wallet transaction in a database locally, something like MySQL or MongoDB, and then run your queries on that database.
You can sync your local database with the Bitcoin wallet via RPC by periodically calling listsinceblock() and keeping track of the last block or by running the client with the optional -walletnotify parameter to run a script to notify your database of new transactions.
Be careful with -walletnotify however. It will be called twice for every transaction and if you have a lot of transactions, it can happen a lot. So make sure the command -walletnotify calls doesn't use a lot of CPU/RAM.

Hey, this is exactly what I am trying to do, store deposit transactions for each unique user address from the output received from listsinceblock. I would like to ask, when computing the sum of deposits for each unique user address, does one consider transactions only of category receive and generate and ignore all other transactions categories?


text:
What is the strategy behind a sell wall?
I understand the idea behind 'bid walls', but on Kraken, prices are being kept low through the use of 'sell walls'.  The volume on this exchange is too low to have a chance of getting through these walls, even when prices on other exchanges are skyrocketing. Every so often, when the price falls a bit, up comes a new 'buy wall' keeping it there. The price on Kraken falls when other markets fall, but gets stopped at the wall on the way back up.  I am curious to know what the strategy behind this tactic could be.

Added 21 Nov for elucidation
On this small volume exchange, a 30 BTC ask equals 10% of the 24hr. volume.  It is the equivalent of a 4500 BTC ask on Bitstamp.  It alters the way bidders approach the market.  When you see such a wall sitting just above the current price, you can be sure the price will not be rising beyond it for at least the next few hours.
I watched this person re-position this block four times over the course of the day.  Each time, lowering it to sit just above the current bid price.  It was altering the dynamics of this small volume exchange.
I am not asking for you to read anyone’s mind.  I was baffled by this behavior.  I had not seen this strategy before.  I thought that there must be some method to this madness, but I could not see what I might be.  I thought that somewhere in the collective experiences of Stack Exchange there might be someone who was familiar with this strategy and might be able to provide some insight, not necessarily on this person’s behavior, but on the theory behind the strategy being employed.  Assuming, of course, that there is one.

I think you're missing something fundamental here. These walls don't come from the exchange or from an individual person or source, they're the cumulative result of the actions of everyone trading (speculating) on that exchange. There's no one strategy that leads to or explains bid and ask walls. You're thinking micro when the problem is macro.

Thank you for taking the time to write a reply, but you seem to have missed the point entirely.
I am not asking about the origin of the wall.  I am asking if there is a known strategy that involves keeping the price from climbing by placing an ask order at more than 60 times the mean trade volume at the just above current bid price.  Such a disproportionate ask order that suddenly appears, then vanishes and reappears moments later at a new price is not the work of spontaneous generation or the natural result of cumulative actions as you seem to be suggesting.

@DavidPerry: It could be the work of an individual person: a single large investor who decides, for whatever reason, that she wants to unload a bunch of coins all at once.  If she changes her mind a few times about what price she wants, you'll see the wall move around.  I don't see why this should suggest that she's trying to affect the larger market in some way; she might just want to make a big trade.  But there could be something I'm missing.

@NateEldredge: True, but it still remains that at worst this question misunderstands fundamental concepts and at best it's asking us to be mind-readers.

related: http://bitcoin.stackexchange.com/questions/2944/what-is-a-bid-wall

Further investigation leads me to believe that this wall could have been providing insurance to support a short position.  A risky strategy, but do-able considering the unique opportunities possible due to the dynamics of this low-volume exchange.  Of course, since the volume is so low the ROI would also be pretty low.  Thanks for your help.

A large investor might be trying to move the market.
Sell walls create an impression of a strong supply. This makes some people, unwilling to wait for the wall to break down, pitch their sales offers below the wall. By moving the wall closer to the current bid again, a large investor might be able to move the market to a small extent and then buy at a lower price. The investor's goal is to move the market, not to actually sell his supply at that price, so when the price gets too close, such walls often disappear or move to a higher price. Especially, if you see the same amount popping up at different prices, there is probably someone trying to move the market without actually fulfilling orders or bids.
Another type of sell wall is composed of many combined sales offers at certain landmark prices, e.g. $600. These usually don't move around.

I use this type of trading to accumulate buys at a cheaper price. Ex: if I spend 2 hours buying small amounts of coins so nobody notices the large buys, then I put up a large sell wall ($30k-$45k) to encourage sells. After that pushes down the market from panic sellers trying to under sell my wall, I instantly buy those sells up and remove my wall and then put in a buy order for enough tokens to raise it 3%-7%. That gets traders attention and I let them take the rest over and pump the price 10%-15% more. Then I drop my accumulated coins on them. Usually, I buy up the orders down to my original 3%-7% I purchased to build the trade tension and that gets written off as me just paying trading fees and the rest of the coins are all profit. This is 1 reason you may see some decent sell walls on random coins that are used just to push the price down.

http://www.dancingbots.com [1] is visualizing the chronological sequence of limit orders on popular exchanges. You can see how those walls are repositioned if the price moves.
Those big positions are an exception. More often those walls consists out of multiple positions spread over a price range. They show up as parallel horizontal lines. If you look at a the usual orderbook graph those spread out positions give an impression of an authentic orderbook imbalance.
Another variation are lots of smaller positions which are canceled after a few seconds reopened gain at a similar price level. I guess they also try to give the impression of a oderbook imbalance, but at the same time try to pretend that the slope is getting steeper. Maybe they try to trigger buy decisions of other bots.
[1] I am the creator of dancingbots.com.

I understand both lines and dots represent limit orders. Are dots those limit orders that get posted and then get removed quickly? And the lines are those limit orders which stay persistent for as long as the length of the line?

Amazing website! Is there any chance you are open sourcing it? Cause I would love to look at the code.

@Tanmay Yes, your understanding is correct. But a line doesn't necessary represent a single limit order. It shows the summarized amout of limit orders at this price. Those lines at round numbers are usually the result of many smaller limit orders. Hint: Don't use round numbers like 500 for your limit orders, subtract or add a penny (eg 499.99 for a sell order) to ensure your limit order will be executed.

The point of sell walls is to encourage people who are in need or urge to sell their coins at a lower price,thus keeping or moving the market in the direction needed by the owner or owners of the stack.
Hope that makes sense.

I thought they existed because without them you could simply leave a trail of 0.001 btc or something all the way up the prices to much higher price in an order book without spending much money. The value shoudl be the market cap / coins distributed. If there is not that much in the currency then it can't achieve that price level there needs to be enough money invested to meet the market cap required for that level of price..  But that was only what made sense to me when analysing the same situation on exchanges. I could be wrong.

An explanation that nobody has touched on is arbitrage. As stated in the original question:

The volume on this exchange is too low to have a chance of getting
through these walls, even when prices on other exchanges are
skyrocketing.

Whales can use this technique to effectively cap the price on one exchange allowing them a reservoir of cheaper BTC to buy from and sell for an immediate profit on other exchanges.
Here's an example using two exchanges:

Whale puts 100 BTC for sale at $20k on an Exchange A where the daily volume is 30 BTC, effectively creating a sell wall and preventing the price from moving up on Exchange A.
The price of BTC on Exchange B moves up to $21k. The whale goes to Exchange A, buys 50 BTC, bringing the price down to $19.5k.
The whale sells the 50 BTC on exchange B for a profit of $62k.

Using this strategy on two or more exchanges of sufficiently different liquidity, the whale can repeat this strategy to create larger and more arbitrage opportunities, for example:

With the price on Exchange A now lower, the whale moves the sell wall of 100 BTC down to $19.5.
The price on Exchange B continues to increase, allowing the whale to rinse and repeat.
Once sufficient profits are made, the whale can move the 100 BTC on Exchange A to the same price as Exchange B and profit off market forces bringing the exchanges into equilibrium, or simply take their BTC off the market once they've made a profit, keeping the BTC used for the sell wall in the process.

Note that other traders seeking arbitrage opportunities will be competing with the whale in this example, but as long as the whale is able to keep a wall up that is larger than the average volume on that exchange, they're effectively in control of the maximum price BTC can sell for on that exchange.

Sell walls are whales trying to suppress the price of a currency, usually in order to buy up more of it themselves.


text:
Multibit: Connecting
I am not able to connect to my wallet using Multibit ("Connecting..." on the bottom left corner). Im using the TAILS OS (Multibit and my wallet are located in the "Persistent" folder). After reading the log, the problem probably has to do with the port 8333 (Peer dies), which I forwarded via my router settings though. I also checked netstat to see if the port is listening and its not. I googled and found a few threads with people having similar problems, some recommended forwarding the port (which I did), some recommended configuring a proxy in the Tor settings (SOCKS5, 127.0.0.1:9063), but nothing seems to solve the problem. I'm wondering if it's a common one and I seem to be pretty incompetent when it comes to trying to solve it, so  please, help me. ;)
Edit: Quick update. I now tried switching to Electrum, which doesn't connect either. Then I tried out Bitcoin-Qt, which synchronizes forever until my laptop crashes (3 attempts so far)..Is this so hard ?? ..

Possible duplicate of Running Multibit on Tails - connecting error


text:
Can I send btc to a totally offline wallet?
I want to setup a totally offline armory wallet. is it possible to send btc to a totally offline pc? Is it also safe, I guess it must be synchronized with the whole network, right? And there is something else, armory gives a paper wallet with a long code, can I use this code with any other software, in case something happens to armory?

Yes to both questions.
You only need a wallet connected to the internet to remove coins from your account, not to add new ones to it.
A paper wallet can be used with any bitcoin wallet application.

Adding to the other answer...
Not all wallets have support for offline/paper wallets.
Mycelium has the best support for offline wallets because it allows you to spend directly from the private key of an offline wallet. Mycelium likely recognizes all the private key forms that Armory can produce.
The version of Armory you have would continue working even if updates were to end. Armory appears to be open-source on github.com; therefore, updates will not end as long as there is a need for an update.

Its true that not all wallets have direct support for paper wallets, but with every wallet there exists some way to import a paper wallet, even if that method is hand rolling a wallet.dat file and placing it in the source.


text:
How can get Bitcoin client API account(<account>) name
I have setup the BIK_php API of  http://bitcoindevkit.com/  in PHP.
Now, I am able to connect and generate new addresses, but when I am going to call some functions like getaddressesbyaccount, sendfrom etc as given in Bitcoin API call list at https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_Calls_list , these functions requires "account" parameter as , but I could not understand where from I can get the account value?
So, Please let me know what will be the value of , and how can I get the   value from?

Does BIK_api (I don't know it) even use the accounts feature of bitcoind?

Thanks to comment! Is the Bitcoin Address Label is known as account name here? If we use External Bitcoin address then How can get the account name?

Addresses are not accounts. Accounts is for when for example you want to implement several users' wallets shared in one real wallet. They're just virtual balances, and have nothing to do with coin selection. There are few use cases for it, and few systems use it.

Thanks! Yes addresses are not accounts but when I call getaccount() of BIK_api API by passing bitcoinaddress then it returns bitcoinaddress Label. So, I just want to confirm that the bitcoinaddress Label is the account name?

If a receive address R has label L, then payments sent to R will credit the account with label L. So yes, they coincide, but are not the same thing.

Ok, But if not same thing then what is the account name? and  in your case if we run getaccount(R) then it will return account L, so very confuse here between Label and Account?

From the API page that you linked:
getaccount <bitcoinaddress> Returns the account associated with the given address.


text:
How do I use walletnotify?
I have bitcoin daemon and I want to use the walletnotify option with a json-rpc call. Some of the examples use a "transaction.sh" file for walletnotify. What is it for?
What do I have to write in that sh file, to make walletnotify work for more than 6 confirmations.

Just put a ruby CLI command in the .sh file to run your ruby script. A .sh file is basically a command line.

Found this thread helpful: https://bitcointalk.org/index.php?topic=203438.0

First you must configure your bitcoin.conf file for JSON-RPC
rpcallowip=127.0.0.1
rpcuser=yourusername
rpcpassword=reallystrongpasswordthatsnothis
rpcport=7788
walletnotify=/home/scripts/transaction.sh %s

Where transaction.sh is some bash program. One approach is to have it make an http request to some process to notify you of the deposit. An example:
#!/bin/sh
curl -d "txid=$1" http://127.0.0.1/some/route

walletnotify will execute transaction.sh every time you either

receive bitcoin
send bitcoin
when a bitcoin gets its first confirmation

%s is the transaction ID or txid which gets passed to transaction.sh.

What if I receive more than 1 transaction in a block? Does it spawn a new process/thread using the bash program for each transaction?

@pferg it spaws for each transaction and for each block. the only question is: what if you receive multiple inputs from multiple outputs within 1 transaction. ist that even a thng? (i send you 10x 5 BTC within 1 transaction. i think you receive 1 OP with 50BTC)

to complement Loourr's answer, %w can also be passed to your script, informing you of the wallet in the node that received the funds, since you may have > 1 wallet


text:
How to use Bitcoin Wallet with MtGox?
I downloaded the Bitcoin Wallet from bitcoin.org; it's on my PC with a $0 balance. I want to purchase some bitcoins with dollars on MtGox, but how do I make it such that my purchase shows up in my wallet?
I have an account on MtGox, but I don't see anything under Funding Options where I can link my wallet with the MtGox transaction, then again, I've never purchased Bitcoins so maybe I'm misunderstanding something.

You need to buy bitcoins on MtGox using another currency. These bitcoins will show up on your MtGox account.
You can then withdraw these bitcoins from your MtGox account to your own wallet. You can find this under Funding options > Withdraw funds > Bitcoin. Enter the address your wallet gives you and MtGox will send your coins to that address so that they show up in your wallet.

So in my Wallet there's a Receive Coins tab with a default address; I use that address in MtGox to withdraw into my wallet?

Yes, that's the way it works. Compare the address with your bank account number that you have to enter when you want to withdraw other currencies from MtGox or similar trading sites.

I see, and if I want to deposit bitcoins from my wallet into my MtGox account, I use the random address MtGox provides under the Add Funds tab?

Yes. But don't save the address, it will probably change over time so only use it immediately after you got it from MtGox.

I live in the uk and am trying to purchase bitcoins from mt.gox. I dont know what option to use for this, it says there is a bank transfer option and OKPAY option(which seem to be the only available options for citezens). |Can anyone help???
Thanks

Please ask your own question.


text:
Will my bitcoin wallet take prohibitively long to sync as daily transaction volumes grow?
I'm using Bitcoin-qt on Mac and it's been a few weeks since I last fired it up, so it's doing a sync. I've waited a few hours now, despite being on powerful hardware and a fibre connection to the web.
If I understand it correctly, the sync involves some processing for every Bitcoin transaction performed globally. In the bright future of Bitcoin, when people are buying Mars bars with them, won't the sync be prohibitively slow due to sheer volume?
Or are we hoping Moore's law will offset this growth?

The points mentioned in this answer apply here. The key points are:

End users won't be expected to run full nodes such as bitcoin-qt, but rather lightweight clients such as Multibit or Electrum.
Not all Bitcoin payments need to take the form of Bitcoin transactions; most will probably take some form of trustless, instant, off-the-chain Bitcoin payments


text:
What does "proof of reserves" and "proof of liabilities" mean?
What is a brief way of describing what proof of reserves and proof of liabilities mean?
What is their difference?
I have searched and read but I haven't got it yet.
Is it done by an auditor? Is it an audit?

What do you mean by "in 2-lines"?  Are you looking for an answer that is only 2 lines long?

Yes! I am sorry. I was trying to say that I wanted a brief explanation

I updated your question for clarity.  Keep in mind that not all answers can be kept short, especially if you want them to be correct :)

Ok! Then I dont mind having a no-brief exaplanation :)

Proof of reserves: This is proof that you actually control at least a particular amount of particular assets.
Proof of liabilities: The is proof that you do not owe more than a particular amount of particular assets.
So, for example, if an exchange can prove that it has reserves of 15,000 Bitcoins and that its owes its customers no more than 14,500 Bitcoins, then it has proven that its Bitcoin holdings are solvent.

Does "proof of reserve"s mean the same as "proof of assets" ? Thank you

@elenaa They can have slightly different implications, but their meanings overlap. For example, if you wanted to borrow my car and I wanted to be sure you could pay for any damage you might do to my car, I might demand a proof of assets. But that wouldn't be a proof of reserves because no obligation currently exists to reserve funds to meet. Reserves are assets reserved to cover specific liabilities.


text:
Sending Bitcoins from a Mastercoin Address
Is there any danger in sending any remaining bitcoin funds that are still sitting in a Mastercoin address, i.e. the bitcoin address from which one sent funds to the Exodus address?

No, it's completely safe.
To send mastercoins you have to use one of the mastercoin clients - you can't accidentally send mastercoins by working with a Bitcoin wallet.


text:
Can the Bitcoin protocol support very small transactions effectively?
Say in a few years Bitcoin is where we hope it is, like $1000 or even $10000. In such a scenario one cent is about 1-10 microBitcoins (1 millionth or 0.000001 BTC).
In my experience, attempting to use bitcoins for small transactions (even of order 0.001 BTC) usually either takes a very long time, or just doesn't get processed at all. It thus worries me that BitCoins cannot be used for small transactions which correspond to a big and important part of the economy (e.g. a kid buying a Popsicle, or giving a $1 tip, or buying bigger stuff in third world countries, etc.)
Does anyone has a useful perspective on this issue?

You must be rich now

The answer is multifaceted.

Microtransactions were not a design goal of Bitcoin. Even if they're not well supported, that's ok.
Off-chain transactions might be used if on-chain microtransactions are too expensive.
There are a few possibilities to implement microtransactions on the blockchain. One such implementation was recently added to bitcionj. Also see this interesting proposal for nondeterministic nanopayments.
Alt chains for microtransactions are a viable solution as well.

TL;DR - it's not a problem.

Currently bitcoin protocol does not suit very well for microtransactions
http://simondlr.com/post/46590540723/unfeasible-micro-transactions-in-bitcoin
https://bitcointalk.org/index.php?topic=196138.0
However, there is some work going on which tries to work around limitations
http://thegenesisblock.com/off-chain-micropayments-implemented-in-bitcoinj/

This is only my view and kind of skirts the question (but not really).
microtransactions between individuals may use the blockchain, but as bitcoin (and others) grow, the services surrounding them will also and the transactions will move off of the blockchain.  Look at the current exchanges.  There are hundreds of transactions going on at any time.  None of them are in the block chain and they shouldn't be.  I see it moving this way commercially.


text:
BTG wallet or exchange with BIP39 seed import
Can anyone recommend a Bitcoin Gold exchange or SPV wallet for Linux that supports importing wallets from a BIP39 seed? The best I’ve found so far is a fork of Electrum that supports BTG for Windows or exchanges with no wallet import.

Take a look at the Ecosystem section on the Bitcoin Gold website for a list of wallets and exchanges that support BTG

Thanks: I did have a quick look through there already. The wallets all seem to be for mobile (and, e.g., Freewallet hides away the technicalities) and of the exchanges I checked, many were no longer supporting BTG and none (that I saw) allowed wallet import :(

This doesn't answer the question directly, but Coinomi running in Genymotion works and allows restoration from a BIP39 seed, per the instructions given here:
https://medium.com/@coinomi/collecting-your-free-bitcoin-gold-btg-coins-da937d4255d1
Genymotion can run under Linux, so while it's a bit of work, one can achieve the desired outcome using this method.

Annoyingly, when I managed to reclaim my BTG address, it appears that the contents had been stolen! Fortunately, I had moved my BTC already, to avoid just this scenario, but let this be a warning to others. The only other place I tried the seed was an online wallet -- admittedly a stupid move, on my part -- which, judging by my history, was mybtgwallet.com. That site is now down and giving a certificate error, so I think there's quite a high probability it was a phishing expedition :(

Live and learn, I suppose... https://bitcoingold.org/wp-content/uploads/2017/11/Statement-on-MYBTGWALLET.pdf


text:
Tax deduction for US-based employer paying in Bitcoin to overseas contractor
My employer can write off business expenses (my salary) if he pays me via wire transfer, PayPal, Payoneer and some other international payment systems. Is there a tax-deductible method for him to buy Bitcoin and send it to my wallet (or to my account from where I can withdraw to my wallet)?
I'm no good in legal terms, so feel free to edit the question if you understand what I'm talking about.

I don't at all see why he couldn't purchase bitcoin through Coinbase or similar and deduct it. That should be entirely deductible, even the fees paid to buy the bitcoin (bank fees plus whatever Coinbase is charging these days).

Thanks. I guess it's better if he sends it to my account (with my real name) rather than to my (anonymous) bitcoin wallet. Anyway it needs accountant consultation.

Yes. I would think it would be treated just like a bank transfer, except that he's purchasing the foreign currency himself and transferring it. Don't forget to accept!


text:
Is there data on the geographic distribution of bitcoin users?
If you are a company wanting to adopt bitcoin as a payment method or an academic wanting to study the bitcoin market it is important to know as much as possible about the bitcoin users. Since bitcoin is pseudonomous it is hard to gather direct information on the users. However, if users want to make transactions then they need to broadcast to the network. Although the IPs are not stored in the block-chain, there are ways to learn them. With the IP addresses, it is possible to use IP Geolocation to get an idea of where the user is. Hence the question:

Is there data available on the geographic location of users of bitcoin? Especially on volume of bitcoin transactions from given geographic areas?

Or is it impossible or unlikely that such data can be gathered? If the majority of users use Tor for instance, then it would not be possible to get a good location data. Are there other technical constraints that make it impossible to use this or other approaches to learn the geographic locations of a large number of users?

Meta note
Since bitcoin is new, it is possible that such data is unavailable yet just due to the novelty. Please don't provide such answers, we can just wait until such a study is done and given as an answer. A 'no' answer is interesting only if it explains a technical constraint that would stop such studies from ever happening.
Also, it is possible for a committed user to invest effort in order to hide their location. However, unless there is reason to believe that most users use such efforts, this is also not a very relevant answer.
This question is an attempt to turn our lowest voted question into a legitimate specific question.

*quality meta note!

Related: http://www.businessinsider.com/927-people-own-half-of-the-bitcoins-2013-12

This shows bitcoin nodes based on IP address location.
http://www.weusecoins.com/globe-bitcoin/  (UPDATE: link is broken)

You say "(miners)" but also "bitcoin nodes". Is this just miners or everyone running a client?

It is bitcoin nodes. This actually won't include many miners as they tend to use mining pools and don't necessarily run Bitcoin nodes.

Here is a map showing where bitcoin meetup groups have formed around the world.  http://bitcoin.meetup.com/

Your link is not working anymore. I found two others, although I dont really know if they tell the same: http://blockchain.info/nodes-globe and http://bitcoinglobe.com

This is why we typically prefer explanations rather than just pasting in a link.

Quote from question:

Also, it is possible for a committed user to invest effort in order to
  hide their location. However, unless there is reason to believe that
  most users use such efforts, this is also not a very relevant answer.

It's not likely that most people will try to hide their location but it's still pretty likely that the location of nodes won't reflect the location of users. Computer usage today is more and more about web applications and less about downloading programs so it's not a wild guess that online wallets will be the choice of most "regular users".
The best source for location data about bitcoin users in the future might prove to be visitor statistics from Bitcoin web sites (merchants, e-wallets, exchanges etc.).

Check this out - the Country of Host charts shows a geo distribution of p2p clients over time. The site has loads of other interesting stats.

interesting link, but bad answer since it provides zero-context for the link. I think you should give a little summary of what we find on the other side of that link.

@Artem - right you are. Corrected.

Your link is broken...

BitNodes.co shows a global map of Bitcoin nodes.

I looked at this back in 2011. It was easier then as Bitcoin clients used to all connect to an IRC channel:
http://41j.com/blog/2011/09/the-distribution-of-bitcoin-users/
Overall the majority of clients were in the US and Germany at that point.

Interesting blog post! However, you could perhaps extend your post here a bit. By the way, if you consider population size, the US isn't that "far ahead to everyone else": Your numbers divided by population sizes give e.g. 8,68 clients per one million inhabitants in the US and 10,77 clients per million inhabitants in Germany.

There are a number of sources for geographic distribution data, depending on your specific needs. There is an extra-fancy WebCL globe with sort of a 3D bar graph showing node density, a simpler Google maps mashup for those who don't have (or don't need) WebCL and of course neither of those could exist without raw data (KML format).
All data is based on IP address geolocation of individual nodes.

nice answer, but it refers to the same data as osmosis' answer from 9 hours before your answer. Why not just edit his answer to add these relevant links?


text:
What economics/finance methods and tools can be used to analyze and predict the Bitcoin market?
Bitcoin differs from standard markets in many ways. Some standard market analysis tools are inapplicable due to unique features of Bitcoin. Hence the question

What methods/tools can used to analyze and predict the Bitcoin market?

It is better if the tools have a proven trackrecord of actually working for predicting the Bitcoin market, but it is unlikely that such examples exist. Therefore, I am perfectly happy with references to the literature on econ/finance tools that should work for the bitcoin market but maybe haven't been applied yet.
Related questions
Is there a correlation between Technical Analysis predictions and actual prices?
Can bitcoin transaction data be used to study markets?

This smells like investing advice to me--I doubt you'll find an expert on that here.

@eMansipater not really financial advice (or at least that was not my intent) as more of a technical question (since my interest is mostly academic) of the sort one might ask at quant.SE. Unfortunately, I can't ask that question there, since it requires much more knowledge about bitcoin and its users than it does about quantitative finance to answer... however, if I don't receive an answer here and find a good way to rephrase the question for a more general audience, then I will cross-post to quant.SE.

@eMansipater if you have specific comments on why it sounds like investing advice, then you are welcome to edit my question or make suggestions and I will try to edit the question into better form.

I guess I'm inclined to just take "Bitcoin differs from standard markets in many ways" as an unsupported assertion, and then the ensuing "How can I predict?" sounds like any investor wanting to predict the performance of a stock/commodity/etc.  It seems like being able to prove that first claim in any particular respect would itself yield your answer.

See my similar question on Personal Finance and Money - Stack Exchange from last June: What technical indicators might be appropriate for analyzing Bitcoin currency trading

Technical analysis is important, but right now I think that one should not rely exclusively on chart analysis and indicators to predict Bitcoin's price movement. For example, at the end of July and mid-August some indicators, such as MACD or RSI, clearly showed a trend inversion that did not happen.
One of Bitcoin's unique features is the mining system and I think that, right now, this plays an important role in price analysis. After Bitcoin hit $30 in July, many people invested in mining rigs and difficulty rose a lot. Those people are looking forward to get their investment back and, since Bitcoin is extremely infalctionary right now (50 new coins every 10 minutes), there is a big selling force at the markets.
If miners sell 30 coins out of each block, we need around 1 million dollars per month to keep the price at $5.
I also believe that the $30 spike was caused by media exposure. Such a small market can be easily manipulated by a few serious investors.
Main points:

Use Technical Analysis carefully.
Consider the number of coins per block and the money invested by miners
Keep an eye for important news that may attract new investors to the market

To finish, here is one stock behaviour that I could identify: the dead cat bounce.

A dead cat bounce is a trading term used to define when a stock in a
  severe decline has a sharp bounce off the lows.

http://bitcoincharts.com/markets/  and http://bitcoinwatch.com/ are both good resources
I also heard about a SierraChart Technical Analysis tool over at campbx dot com

both of those links are just market data. The technical analysis tool reference you provide is specifically addressed in one of the related questions I list, and the link I give already argues for why it might not be such a good predictive tool. can you edit your answer to explain how it answers the question?

I would beg to differ that the charts on bitcoin charts are a far distance from raw data. They are quite configurable. I don't see any reference to the SierraChart tool that I mentioned in those questions. Perhaps you could include some information about it in your question. My answer refers to some tools, but I can not cvouch for their performance. If you want information about their performance then I suggest you edit the question title as such

I hazard that you might be better off manipulating the market than trying to predict its direction. The BTC market is not that large, and seems to be subject to fluctuations when big "events" happen such as a hacking attempt. Perhaps hacking MtGox or defacing bitcointalk.org is a better way to manipulate the price than Bollinger bands?

Hacking websites is not a way to analyze the market.

I'm not advocating manipulating the market; however, the thing with technical analysis of markets is that as soon as someone finds a good strategy, others copy it and that strategy's profitability is quickly erased. If you haven't read "A Random Walk Down Wall Street," I can heartily recommend it if you are interested in an easy to read analysis of the efficient market theorem -- essentially why trying to predict the future direction of free markets is not profitable for most investors.


text:
bitcoind replies 500 error
I'm trying to setup pushpool + bitcoind.  However, when I connect to pushpool with cpuminer I receive this error:
[2013-04-21 12:47:47] json_rpc_call failed, retry after 30 seconds
[2013-04-21 12:48:17] JSON-RPC call failed: {
   "code": -2,
   "message": "upstream RPC error"
}
[2013-04-21 12:48:17] json_rpc_call failed, retry after 30 seconds

I see this error in the pushpool server log:
root@ip-10-28-79-184:/usr/local/sbin# ./pushpoold --debug=2 --stderr --  foreground --config=/usr/local/sbin/server.json
[2013-04-21 13:26:28.319949] Debug output enabled
[2013-04-21 13:26:28.333064] Forcing local hostname to localhost
[2013-04-21 13:26:28.456350] Listening on host :: port 8336
[2013-04-21 13:26:28.456477] Listening on host 10.28.79.184 port 8334
[2013-04-21 13:26:28.485367] initialized
JSON protocol request:
{"method": "getwork", "params": [], "id":1}

About to connect() to 127.0.0.1 port 8332 (#0)
   Trying 127.0.0.1... * TCP_NODELAY set
 connected
 Connected to 127.0.0.1 (127.0.0.1) port 8332 (#0)
 Server auth using Basic with user 'username'
 POST / HTTP/1.1
Authorization: Basic dXNlcm5hbWV2YXN5YTpwYXNzd29yZHZhc3lhMTQ=
Host: 127.0.0.1:8332
Accept: */*
Accept-Encoding: deflate, gzip
Content-type: application/json
Content-Length: 45

 The requested URL returned error: 500
 Closing connection #0
[2013-04-21 13:26:31.743119] HTTP request failed: The requested URL returned error: 500

bitcoind config:
testnet=0
server=1
rpcuser=username
rpcpassword=password
rpctimeout=30
rpcallowip=*
rpcport=8332
rpcconnect=127.0.0.1
gen=0
keypool=256
paytxfee=0.00

pushpool config:
{
    "listen": [
        {
            "port": 8336
        },
        {
            "host" : "server_ip",
            "port" : 8334,
            "protocol" : "http-json"
        }
    ],
    "database": {
        "engine": "mysql",
        "host": "localhost",
        "port": 3306,
        "name": "bitcoin",
        "username": "mysql_username",
        "password": "mysql_password",
        "sharelog": true,
        "stmt.pwdb": "SELECT `password` FROM `pool_worker` WHERE `username` = ?",
        "stmt.sharelog" :  "INSERT INTO shares (rem_host, username, our_result, upstream_result, reason, solution) VALUES (?, ?, ?, ?, ?, ?)"
    },

"pid": "/tmp/pushpool/pushpoold.pid",
"forcehost": "localhost",
    "log.requests": "/tmp/pushpool/request.log",
    "log.shares": "/tmp/pushpool/shares.log",
    "auth.cred_cache.expire": 75,
    "rpc.url": "http:// 127.0.0.1:8332/",
    "rpc.user": "username",
    "rpc.pass": "password",
    "rpc.target.rewrite": true
}

I have tried to change ports, and even rebooted the server,  nothing helps.

It's due to miss-sync of bitcoind in my case.
Just wait the bitcoind sync with the bitcoin network (9GB actually), and after you can use it.
du -ksh ~/.bitcoin/ will give the size.


text:
Bitcoin-qt, OS X Mountain Lion, blockchains, and bootstrap.dat
Edit:  Rewording this question to be more clear and concise.
Background Info:

Was running bitcoin-qt .0.8.1 on osx mountain lion.
experienced a kernel panic, likely from some conflict between mac ports and homebrew. Hardware was tested and does not seem to be the culprit.
upon next restart of bitcoin client I have a corrupted database and eventually the entire blockchain needs reloading.
only had a small amount of coins in wallet but was hoping to use them sooner than an entire blockchain download would take using the client (x days where x >= 2).

Things I tried

Restoring the relevant files in the data directory from the last
backup before the crash. Actually had one from that morning.  Did not
really work -- client would trying to verify the db and eventually
would crash.
Got the latest bootstrap.dat from torrent, and tried placing  in data
directory. This eventually sort-of worked after next two steps.
Eventually imported wallet.dat at blockchain.info as a stop-gap, but it turned up a few bitcents short. I think because I had sent something to a wallet address before this happened and it hadn't synced yet.  I'll figure that one out once I'm fully synced, and if I ended up losing $5-10 worth of btc into the ether somewhere, I'll get over it.
Fixed the probable cause of kernel panic and reinstalled/upgraded to
latest 0.8.3 client and retried the above steps.
Also had to pretty much nuke the data directory in order to get bootstrap working.  (renamed/moved actually just in case) Saved wallet.dat (encrypted) elsewhere.

At this point the bootstrap method seems to be working.  The client reports importing block from disk.  However, it soon becomes apparent that this method does not really make things any faster.  It seems to load the blockchain from my HDD at about the same rate it downloads from the network.  Also, latest update was apparently 13 weeks old, and those last 13 weeks make-up most of the payload...
So for now I've got my old wallet imported onto electrum, and bitcoin-qt is back home chugging away finishing the download so hopefully I can find that change when it's done and be done with it.
OK, so what are my question(s)?

Wy does it seem to take just as long for the client to import from the local HDD as it does from the p2p network?  If I were smart I would have put the bootstrap file on my SDD, but it appears that's not the case. But still, I'd assume it would be faster than from the cloud.  Any ideas? I don't remember if I have the 5200 or 7200RPM hdd; I probably just got a 52 since I was buying an SDD along with it.
Any blockchain-scalability plans in order for future releases of bitcoin-qt?  Evidently this is growing faster than they expected.
Anybody have a full working procedure for restoring data directory files when you have backups available?  Found a few ideas elsewhere on the net but nothing that worked.  My backup software keeps old versions of files so it's not too difficult to assemble a snapshot with the /chainstate and /block directory contents from some specific date.  But the client was barfing on this method.

Thanks, hope that is somewhat improved.

This question is too long, and there is too much noise to even know what you are asking. Cut it down to 1 paragraph.

Ugh, you're right.   I'll edit it down within the next hour or two.

The "Did I get hacked" in the title doesn't seem to relate to anything in the question.

Bitcoin-qt verifies the entire blockchain the first time it starts, to be sure that all the transactions are properly signed, and all the blocks certify an appropriate amount of computation (proof-of-work).  This ensures, for instance, that nobody is feeding you a fraudulent bootstrap.dat.  Depending on the speed of your computer and network, this verification might be the bottleneck, instead of the download.
There is not really any way around this if you want total confidence in your copy of the blockchain.  The bitcoin-qt client generally is designed for greater security at the cost of performance.  There are other "thin" clients that are less paranoid, and are willing to trust the blockchain they get to a greater extent, but there is a security tradeoff.  Whether you think the tradeoff is acceptable is up to you; many people do.


text:
How get address from pk_script?
We have example in the wiki:
[...]
Output 1:
 40 4B 4C 00 00 00 00 00                           - 0.05 BTC (5000000)
 19                                                - pk_script is 25 bytes long

 76 A9 14 1A A0 CD 1C BE  A6 E7 45 8A 7A BA D5 12  - pk_script
 A9 D9 EA 1A FB 22 5E 88  AC
[...]

What is the pk_script? Is it possible to translate it to bitcoin address being offline (not synced with network)? How to do this?
EDIT:
OK, I understand more right now:
 pk_script
 76 (OP_DUP)
 A9 (OP_HASH160)
 14 (Bytes to push)
 1A A0 CD 1C BE  A6 E7 45 8A 7A BA D5 12 A9 D9 EA 1A FB 22 5E (Data to push)
 88 (OP_EQUALVERIFY)
 AC (OP_CHECKSIG)

A I understand I should use b58encode_check on "data to push" to get bitcoin address. I have found python library which implements b58encode_check (https://pypi.python.org/pypi/base58) and did try with it:
for byte in (0x1A, 0xA0, 0xCD, 0x1C, 0xBE,  0xA6, 0xE7, 0x45, 0x8A, 0x7A, 0xBA, 0xD5, 0x12, 0xA9, 0xD9, 0xEA, 0x1A, 0xFB, 0x22, 0x5E):
    buffer += chr(byte)
print b58encode_check(buffer)

But I got 3RoCeq4K8ddPW6ugcheFoXK4GC2Ajo7ZF which don't look like bitcoin address. What I'm doing wrong?

did you find any answer to translate the script to the address?

See the wiki. Basically you have to extract the 20 byte pubKeyHash (shown as bytes to push) from the scriptPubKey and convert it to Base58 (which is also described in the wiki.  There is no need to be online to perform this operation.

Are you sure that after doing Base58Check on "bytes to push" I will get bitcoin address? I have found this https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses and it looks like they do Base58Check on 25-byte binary bitcoin address to get bitcoin address. And bytes to push are only 20 bytes long. I'm missing something?

On https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses the 20 bytes number after step 3 is the pubKeyHash you will find in the blockchain.  You need to do steps 4 to 9 to get the address.


text:
What is a brief summary of the ECB's report on virtual currency?
On 29th Oct 2012, the European Central Bank released this report on virtual currency.
What is a summary of its comments on Bitcoin?

In the ECB's view,  (Bitcoin) can be used by business (criminals), customers (fraudsters) and savers (money launderers) to perform legal (illegal) activities, but lets ignore it until volume reaches a level where comparison with sovereign currencies reflects negatively on our reputation. The public will then expect us to regulate such digital (rogue) systems (schemes).

Best answer in this stack exchange!

The ECB is a monopolistic institution: it holds a monopoly over the issuing of money on Europe. As a byproduct, any possible competitor is going to A) Be detained and its activity stopped B) Be criminalized or C) Be condemned. Since technology makes impossible to Government to take over Bitcoin, you can expect (C) for a long, long time.
If Bitcoin gets popular in the near future, because of the utter destruction of fiat currency governments are doing, you can even expect to be criminalized or highly taxed for being a bitcoin user.
Free and competitive money/currency is the nightmare of regulators (looters)


text:
What are the consequences of donating bitcoins to WikiLeaks?
The WikiLeaks website provides a bitcoin donation address 1HB5XMLmzFVj8ALj6mfBsbifRoD4miY36v
According to this article from the Sydney Morning Herald, Julian Assange of WikiLeaks has been declared an "enemy of the state" by the US.

Declassified US Air Force counter-intelligence documents, released under US freedom-of-information laws, reveal that military personnel who contact WikiLeaks or WikiLeaks supporters may be at risk of being charged with "communicating with the enemy", a military crime that carries a maximum sentence of death.

Has there been any clarification or further analysis by US govt (or anyone) as to what the consequences would be of sending bitcoins to WikiLeaks?

They would probably be the same as sending other money to them, just a bit harder to trace. I don't think there is much of a Bitcoin-specific problem here.

It's an interesting point, but would it be better addressed on Reddit or the forums rather than here?

@ThePiachu, if you arrange a trade with someone and they provide that address for payment, you wouldn't want police turning up at your doorstep! I believe that makes it Bitcoin specific.

@HighlyIrregular Hmm, good point. I think I'll make some new question about that issue.

http://bitcoin.stackexchange.com/q/5152/323

Bitcoin's anonymity is usually over-estimated by its users. Researchers were able to associate certain donations to Wikileaks with certain bitcointalk users even though the said users probably thought it was anonymous.

I would gladly donate to any enemy of the state.

Having been in the Army and understanding the stance that the US government has taken, I'm sure t will be up to the commanders.  Many of whom will not look kindly on the gesture.  The official stance will be known when they take action.
As you know the transactions are public and there are a number of efforts to build visualization and data mining tool sets.  This article address the anonymity of transactions and describes nicely why there is no real anonymity if someone wants to dig.
http://anonymity-in-bitcoin.blogspot.com/2011/07/bitcoin-is-not-anonymous.html
You'll also notice two other important things about the article.  One is that it focuses on WikiLeaks and that they are using Visualization tool sets.  this tells me someone is already looking to make connections.


text:
How to index the UTXO set efficiently?
I haven't been able to find information on how to efficiently index UTXOs. Can you explain or point me to some resources?
Update: Btw, I understand completely that the notion of address balance is awkward at best, and that it can never really be known with 100% confidence, especially as P2SH transactions gain popularity.

Index for what type of querying?

haven't tried anything as I'm not an expert on indices, but have browsed a ton of bitcointalk and couldn't find anything.
@PieterWuille to query balances for addresses.

So after doing more digging, here's is what I'm thinking: read the chainstate db from bitcoin core, either directly or via rpc, and then flip the index. I was thinking of putting it in a redis hash, with addresses as keys and transactions as values. This way I can use HSCAN to iterate over the transactions that point to an address and get its balance. The reason I want to use Redis is because this datastructure will be updated quite often, and having everything in RAM is good for that use case. What do you think?

Does this answer your question? http://bitcoin.stackexchange.com/questions/5518/how-do-i-access-information-on-blockexplorer-com-or-blockchain-info-without-issu

@NickODell not at all

I believe what you are looking for is and address based index for txout. Have a look here https://bitcointalk.org/index.php?topic=1395749.msg14194272#msg14194272
Your basic idea of keeping a map of address -> txout is ok. You might want to rethink about storing in memory. Current bitcoind chainstate is around 1.2G (compressed state).

how can I know the size of the chain state today?

Currently its around 3.2 GB . You need to run  a bitcoin node and see size of .bitcoin/chainstate directory


text:
Bitcoins didn't arrive to new wallet
I use Bitcoin-Qt. Decided to make another wallet and transfer some bitcoins there. Wanted to give that wallet to my friend as a gift. What I did was:

renamed wallet.dat file to 1_wallet.dat
started Bitcoin-Qt it created new wallet.dat file
copied address of new wallet
renamed wallet.dat to 2_wallet.dat and 1_wallet.dat back to wallet.dat
transferred some bitcoins to new wallet address

finally after transaction was confirmed I still didn't see bitcoins in a new wallet. What I did wrong? Is it possible to get back these bitcoins?

Have you tried starting bitcoin with the -rescan command line option?

cdecker should probably post that as an answer, that's my best guess too. If it was confirmed, it is irrevocably in that second address.

And just to make sure, ... your client is in sync as well?

Removing all block chain and retrieving it again solved this problem. I guess -rescan should help too.