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Questions tagged [bitcoin-core]

This tag should be used for questions pertaining to Bitcoin Core. Bitcoin Core is an MIT-licensed Qt 5 GUI application for the original Bitcoin codebase. Additional/previous names include "Bitcoin-Qt", "Satoshi-Client", and "Standard Client". This tag should be used when referring to the Bitcoin Core software.

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43
votes
4answers
149k views

Import wallet.dat into a new Bitcoin-Qt client

I had Bitcoin-Qt on my computer with several bitcoins in my wallet, using Vista. Then my computer crashed. Finally I was able to get my computer fixed and download a new version of Bitcoin-Qt. Now I ...
39
votes
2answers
60k views

How can I export the private key for an address from the satoshi client?

If I want to transfer an address from the satoshi client into a different client, how can I find its private key to do so?
39
votes
4answers
56k views

Where is the data folder for Bitcoin-Qt?

Where can I find the blockchain, wallet.dat, etc. on each of the operating systems Bitcoin-Qt supports?
35
votes
2answers
43k views

How do I import a private key into Bitcoin-Core?

How do I import a private key into Bitcoin-Qt? bitcoind is nowhere to be found, and pywallet says it requires "bsddb" when I run it, which is also nowhere to be found. I generated some vanity ...
32
votes
1answer
51k views

How can I restore my wallet?

I just purchased a new laptop and I want to decommission my old one. I have a back-up of my wallet.dat file copied to my new PC. What do I need to do to restore it to my Bitcoin (Windows) client? ...
27
votes
2answers
12k views

How can I combine all the tiny amounts I've received to minimise transaction fees, and do I need to?

Important parts in bold, for those who don't want to read the detail! I've received lots of tiny transactions, in amounts sometimes as low as 0.000003BTC. Even though I've also received (relatively) ...
25
votes
2answers
24k views

How exactly does -rescan work?

-rescan is a command line argument that is passed to the bitcoin client after restoring wallet.dat from backup. Which files get recalculated? Which files does the rescan command read? Why is it a ...
24
votes
2answers
12k views

Bitcoin-Qt command line control on Mac

I'm trying to communicate with the new Bitcoin-Qt -server via a command line on Mac. I run ./Bitcoin-Qt -server, the application starts, but my terminal window is stuck on an empty line (no matter ...
23
votes
4answers
34k views

How do I import private keys from Bitcoin-qt to Multibit client?

Question says it. I spent 20 mins Googling. Saw several links on bitcointalk.com but amazingly found no solution to this. Am I the first one trying to do this? Note the following are not the ...
22
votes
5answers
36k views

Bitcoin-Qt setup: Change block-chain file location, settings? documentation?

I am installing Bitcoin-Qt and have been reading about Bitcoin basics, but I found very little information on the client. I have a few questions about the Bitcoin-Qt program (v0.8.1-beta under Windows ...
21
votes
3answers
18k views

How to send bitcoin with a message attached

Is it possible to send bitcoins with an attached message with the transaction? If yes how to do it?
21
votes
1answer
19k views

What's the difference between bitcoind and bitcoin-qt? Different commands?

This is a multi-part question, mainly do to contradictory information from different articles. It's got me all confused. From my understanding, bitcoin-qt is just a GUI version of bitcoind - which ...
20
votes
2answers
45k views

How to use the “Bootstrap.dat” file with bitcoin-qt?

I have searched around, and nothing I find works for me. Downloaded the approx. 10 GB Bootstrap.dat file. Now stuck on trying to link it with Bitcoin-QT. Tried the following command in the console ...
19
votes
1answer
8k views

When should I use -reindex-chainstate and when -reindex

What is the difference between the options -reindex and -reindex-chainstate? Is one of the options faster? When should each option be used?
19
votes
1answer
13k views

Get non-wallet transactions using bitcoin rpc (gettransaction)

I am playing around with Bitcoin-qt. I want to iterate all blocks and all their transactions. So far I've been able to get a list of all tx's in the blocks I want to. Now I want to get information ...
19
votes
1answer
9k views

Bitcoin URL scheme

What is the URL scheme that is used by Bitcoin to copy transaction information directly into the client? Which versions of Bitcoin clients support it?
18
votes
1answer
10k views

Why the signature is always 65 (1+32+32) bytes long?

A signature created by the Bitcoin-Qt client can always be decoded (base64) to a 65-byte array. This array seems (according to https://github.com/bitcoin/bitcoin/blob/master/src/key.cpp#L217) to ...
18
votes
4answers
5k views

Why does the Bitcoin protocol use the little-endian notation?

Why does the Bitcoin use the litte-endian notation? It is less common than big-endian notation, thus when programming low-level applications working with Bitcoin protocol, one quite often has to ...
18
votes
2answers
3k views

Why was the MIT license chosen for Bitcoin?

Given that an open, transparent, distributed p2p network is a central element of Bitcoin project it seems unusual that it is licensed under the MIT license which allows proprietary closed source ...
18
votes
5answers
18k views

How to decode private key from Android Bitcoin Wallet?

I want to import my private key from the android's Bitcoin Wallet (the one created by Andreas Schildbach) but it can export it only in an encrypted way. How do I decrypt the file so I can import the ...
17
votes
2answers
13k views

Should I be running Bitcoin Core or Bitcoin-XT?

I just read about Bitcoin Core and Bitcoin-XT, and I want to know what is the difference between Bitcoin Core and Bitcoin-XT? And which is better Bitcoin Core or Bitcoin-XT?
17
votes
2answers
6k views

How does the Bitcoin client encrypt the wallet.dat file?

What is the algorithm used for encrypting the wallet.dat file?
17
votes
1answer
4k views

Migration from Berkeley DB to LevelDB

In 2013 a new bitcoin core was released and one of the supposed improvement was migrating from Berkeley DB to LevelDB. According to the release notes at bitcoin.org: LevelDB, a fast, open-source, ...
16
votes
1answer
4k views

getrawtransaction error? [Code -5]

I'm trying to read raw transactions but there is a problem; Seems like getrawtransaction only works for recent transactions, old transactions give me the next error: No information available about ...
16
votes
2answers
9k views

What are the safety guidelines for using the Sign Message feature?

bitcoin-qt's dialog box states, "Be careful not to sign anything vague, as phishing attacks may try to trick you into signing your identity over to them. Only sign fully-detailed statements you agree ...
16
votes
2answers
9k views

Warning: Unknown block versions being mined! It's possible unknown rules are in effect

Recently, my full node (Bitcoin Core 0.14.2) displays this for both HD and non-HD wallets: Warning: Unknown block versions being mined! It's possible unknown rules are in effect What does this ...
16
votes
2answers
11k views

ECDSA r, s encoding as a signature

An ECDSA algorithm when signing a given messages produces a pair of outputs, r and s. How, given a sigStr from a Tx can one extract r and s? Are they just concatenated byte arrays of a specific length,...
16
votes
1answer
5k views

What is the use case of bitcoind ZeroMQ?

What is the use case of ZeroMQ implementation for bitcoind which will be merged into Bitcoin Core v0.12.0? Block and Transaction Broadcasting With ZeroMQ https://github.com/bitcoin/bitcoin/blob/...
16
votes
3answers
477 views

What happens if the developers make a controversial change to the “standard” client?

One criticism I commonly hear of Bitcoin is that it merely transfers trust from some sort of central bank or government entity to the developers of the main project. Can anyone provide a clean ...
15
votes
3answers
9k views

Are there Bitcoin password crackers I can use to recover forgotten passwords?

I've lost the password to one of my wallets (it's a small one, don't worry). I was sure I remembered the password ... but evidently I don't. Is there a program that I can use to brute-force my ...
15
votes
1answer
11k views

How to generate SegWit address

How do I generate a SegWit address using Bitcoin Core CLI? Also will I be able to redeem those outputs and send them to a "legacy" address? If so, will this second transaction be accepted by older, ...
15
votes
1answer
18k views

How does “Sign Message” work?

How does "Sign Message" option in the Bitcoin QT client work? I can't find any description or documentation of it. Do I have to use this option to sign some message when I receive bitcoins? If so, ...
15
votes
1answer
13k views

How do I specify in which directory Bitcoin blocks and other data should be stored? [duplicate]

I am on Windows and installed the Bitcoin wallet. The block folder seems to grow bigger everyday and is stored on my C drive in the roaming directory. I would like to set this to some other folder on ...
15
votes
3answers
6k views

How can I limit bandwidth usage in Bitcoin-qt client?

I've just finished the intial blockchain download/verify in my BitcoinQt client (17 hours..) and I now see that BitcoinQt is happily eating all of my upstream bandwidth. (About 110kByte/sec on my ADSL ...
14
votes
3answers
7k views

Attacking Bitcoin with a supercomputer

The difficulty in Bitcoin is recalculated every 14 days. What if immediately after this difficulty adjustment someone targets Bitcoin nodes with a supercomputer and start creating new blocks? Such ...
14
votes
3answers
5k views

Can Bitcoin-Qt be configured to trim the blockchain?

I run Bitcoin-Qt and Bitcoin Armory on a laptop. I don't have the space to store the whole 20 GB (or however big it is now) blockchain. I understand the need to run through the entire thing for ...
14
votes
2answers
6k views

How can I setup Bitcoin to be anonymous with Tor?

Bitcoin is billed as many things, among them its anonymity is highly regarded. While it is true that a transaction does not identify a user or wallet, recent news shows that there is the potential for ...
14
votes
2answers
778 views

Why does the age of the coin in my wallet matter?

When a new transaction is made, the client seems to prefer older coins in the wallet. What is the rationale for this? Are there any cases where it doesn't make sense to strictly collect coins by ...
14
votes
5answers
651 views

Why does the standard Bitcoin client not display the balance per address?

Any Bitcoin wallet holds several bitcoin addresses. Such addresses are either generated manually from the GUI addressbook or automatically collecting the "change" of a "Send" transaction. The total ...
14
votes
1answer
12k views

How do I upgrade my Bitcoin client?

I am working with an older version of Bitcoin and want to upgrade to version .4. Is there a specific way to do this? I want to try to upgrade, but am paranoid that I could lose my wallet if I do ...
14
votes
3answers
3k views

Estate planning: how can I ensure my bitcoins are inheritable?

What are good ways to ensure my bitcoins can be inherited by my family when I die or become permanently incapacitated? I think there are probably two significantly different situations to account for,...
13
votes
1answer
9k views

What is P2PK, P2PKH, P2SH, P2WPKH - ELI5

Explain like I'm 5 years old and my other half of the brain is surgically removed :) I don't want to put a lot of stress on my brain Also what is the difference between BTC held in P2SH and Unspent ...
13
votes
2answers
293 views

What are the privacy implications of filtered blockchain downloads?

There is now "Bloom filter" support in the network protocol for sending only relevant transactions to lightweight clients. What are the privacy implications of the bloom filter? Does it leak any ...
13
votes
3answers
7k views

What is the exact formula for calculating transaction fees?

According to the Wiki: If the blocksize is more than 250 kB, transactions get increasingly more expensive as the blocksize approaches the limit of 500 kB. Sending a transaction when the blocksize ...
13
votes
2answers
6k views

How can I import a private key into the Bitcoin client? [duplicate]

I have a private key and I want to add it to the keys in the Bitcoin client. Is there an easy way to do this?
13
votes
1answer
9k views

How to get a bitcoin address's balance?

I know blockchain.info has an API: https://blockchain.info/q/addressbalance/134dV6U7gQ6wCFbfHUz2CMh6Dth72oGpgH gets the bitcoin address's balance,but it's not open source and must connect to the ...
13
votes
4answers
1k views

Is pruning transaction history implemented in Satoshi's bitcoin client?

The original bitcoin paper suggests a method to discard old transactions. One should compute the Merkle Tree of the entire transaction history, and store only part of the tree. However, I didn't ...
12
votes
2answers
888 views

How would we know the real Satoshi?

Should Satoshi decide to reveal his or her true identity, how can one know the person is the real creator of Bitcoin, rather than a person who hacked the forum login, email address or the like? In ...
12
votes
3answers
14k views

Where can I access the original, Satoshi written Bitcoin code?

The articles of https://bitcointalk.org/index.php?topic=41718.0 seem to be annotated walkthroughs, and I'd like to see the raw code, as it was originally written in the first release.
12
votes
1answer
3k views

Why doesn't the Bitcoin core team develop official Bitcoin mining software?

If I am right, the Bitcoin Core just maintains the software necessary to run a full node. Essentially it's the code for the Bitcoin wallet, which just verifies blocks, but doesn't mine. But mining is ...