texts: Segwit has been locked-in since Aug'17, has it been activated? If so, why are the communities not implementing it?

texts:
Since locked-in Segwit, why most exchanges, wallets & miners are not implementing it. Market complained BTC is slow & costly to transact now. Segwit did improved both, yet acceptance by community is LOW. Why?
BTW, is Segwit developed by Core or 3rd party? If 3rd party, how did Segwit get paid?


texts: How exactly do I run the -rescan command for bitcoin-qt from console on a Mac?

texts: I downloaded the blockchain from a torrent, but when I imported my old wallet.dat file, the balance is not showing.  I am unfamiliar with console operation, so please be as specific as possible.  Thank You!


texts: I am afraid of private key collision... What is the solution?

texts:
I know that there are a massive number of keys, but lets say that someone generate a private key that belongs to me.
I know that is nearly impossible. But I want to make that more and more impossible.

Is the Multisig Addresses is the best solution?
Because even if someone generates a private key belongs to me, he needs another private key to get my money.

Is that the best solutuon?


texts: What methods are currently used to embed additional data into the Bitcoin blockchain?

texts:
Yes, I do understand that it is inappropriate to pollute the already large blockchain with data not necessary to make the currency work. But I know people are using Bitcoin as an underlying system for certain applications, like data storage or reaching common consensus about matters not directly related to the currency itself.

What methods are mostly employed to inject the blockchain with arbitrary data (like custom scripts representing data or payouts to addresses that represent data)? Is there a need to stop this in order to prevent an undownloadable large blockchain from forming in the future? If so, how can this be accomplished?


texts: Is there a mining software that I can run on my webspace (php, ruby, python)?

texts:
Is there a miner written to be run on webspace, e.g. in ruby, php or python?

I know, it will be to slow and its not worth it, but I want to see it though :)


texts: I have a bitcoin-core full node running and I want to access my node in Python, how can I retrieve the blockchain info?


texts: Can you make a water heater by mining Bitcoin?

texts: I read somewhere that you can actually cut down your heating bills by using bitcoin mining based water heaters or air heaters . Is that possible? Can someone give detailed economics on this ?


texts: Using GPU mining with the Bitcoin Wallet

texts:
After asking this question about using the Bitcoin wallet to mine, I am wondering how I can get my GPU involved with the mining work?

Is this possible? or this there other, non-pooling software that I can use to get the GPU of a macbook to perform blockchain validation (aka mining)?


texts: Does my money still grow if I have it in Coinbase Vault?

texts: I just created a Vault account on my Coinbase account. When the money is deposited into the Vault does it stop growing or will it continue to grow based on the coin?


texts: Does Bitcoin Core validate signatures by default?

texts: There have been claims recently of Bitcoin Core not validating the signatures in a block by default. If this is true, can Bitcoin Core even claim to be a full node?


texts: If a currency price is showing ABC per coin and its price % is +X% or -X% then this reference is taken from which last price i.e. which point of time the price is taken


texts: Recovering ECDSA public key from the signature

texts:
How to recover ECDSA public key from the signature?

I know that all is need is a hash of the unsigned message and signature.

But may be there is some detailed method for to calculate ECDSA public key?


texts: What is the most common way for one to announce new Bitcoin-related bounties in the community? Is there some website that mediates in the process, or is everything done through the Bitcoin forum?


texts: Which exchange is better for average users?

texts:
How do bitstamp, btc-e, bitfinex, lakebtc, btcchina, compare on trading fee, deposit way, and withdrawal speed?

Which is the most comfortable for us?


texts: Identifying the type of wallet that's being used?

texts:
Is there any way to identify what type of a wallet a Bitcoin address is associated with?

For example, if you created an address via Blockchain.info, would anyone know it was created through them or know that you're wallet was located there?


texts: What are some resources for non-tea-leaf cryptocurrency trading strategies?

texts:
I've heard of some bizarre cryptocurrency trading strategies that basically amount to reading tea leaves:

patterns of five, referencing that we have 5 senses, 5 fingers on each hand, and thus one can assume 5 patterns in a day for trading, lol
fibonacci analysis

Can you point me in the direction of some resources for somewhat scientific trading strategies that work to reduce trading risk? For instance, here are two that I've heard:

Market Cap Distribution Analysis
Cross-Exchange Arbitrage. Buy cheaper on one exchange, sell higher on another exchange, pocket the difference.


texts: How do I create a shopping cart that accepts Bitcoin?

texts: I need to start a website to sell and buy goods with Bitcoin. Then I need to know how to add an shopping cart system for it. Are there any CMS plugins or modules for Joomla, Drupal, or another? Or can you tell me how to add a shopping cart system for a PHP based website without any modules?


texts: What do the different .dat files contain?

texts:
What data do different Bitcoin .dat files contain? How about the other files in the same folder?

The wallet.dat file is somewhat documented and there are some ways to convert it to human-readable form, but I don't think the same can be said about the other files. What data do they store and how is it encoded?


texts: how to get the whole balance of a privatekey or publickey BTC

texts: As there are some bitcoin address types of one privatekey or publickey. I can get the balance of one address, but how can I get the whole balance of the privatekey or publickey. How can list all the address from one privatekey or publickey. What's more how to process multisig address which generated from not the same privatekey of publickey.


texts:
I want to understand the defense mechanism of the Bitcoin price control.

A rich company can buy a large portion of Bitcoins from different people in different exchanges. Then they can hold on to those Bitcoins, essentially becoming a controller of the Bitcoin economy. A large number of companies can start doing that.

If that becomes the case, then will Bitcoin still be decentralized? Those companies with their fare share of the Bitcoins, can control the price or any other aspect of the economy.


texts:
I think I understand Merkle verification, but I just want to make sure. Consider this following picture where all the blue nodes were sent to me

My question : if the document that I want to verify is the one that hashes to HL, I still need to have HK in my storage right ? Because otherwise I can't compute the Root, to compare it with the real root.


texts: Can someone explain double spending to me?

texts:
I am restoring a backup of my Bitcoin Core wallet on a new PC. I downloaded the complete bootstrap.dat and placed it in ~/.bitcoin. I thought using the bootstrap would make things faster, but importing from disk seems just as slow. Oh well.

Anyway, currently Bitcoin Core has imported blocks through Jan 2014. I made bitcoin transactions after Jan 2014 that aren't reflected in my wallet. That is to say, I have a higher balance available in my wallet than I really should.

Could I double spend these coins by sending them to another bitcoin address that I own?


texts: Getting statistics on bitcoin >transactions< - breakdown by size

texts:
Now that bitcoin is going more mainstream, particularly with the futures listings and so on,

https://www.cnbc.com/quotes/?symbol=%40XBT.1&tab=news

it's quite easy to get statistics on price performance for bitcoin.

However what I want to see is this - quite simply, stats on bitcoin "spends" and that trend over the last weeks, months.

So, ideally you'd really want this broken down as a histogram.

Imagine yourself trying to sell investors on bitcoin: what they want to know is transaction flow:

how many transactions in the last 24 hrs
a graph of that for a few months
breakdown by size .. under a buck's worth, 1-10, over 10

This straightforward information is in my experience the first thing investors look for, when I try to pitch old money on investing in one Bitcoin scheme or another.

How do I get this information? Maybe I'm missing something obvious - it seems to be the first sort of site one would set up to promote bitcoin.

How many transactions in the last 24 hrs ?


texts: I have identified a potential market for a bitcoin exchange. What is the average price for a white label bitcoin exchange having a reasonable amount of features which will allow me to go on production?


texts:
I have an issue that's probably happened lots of people already, so I'm really sorry for asking the same question. My transaction is stuck since 28.12.2017 already. I've accidentally paid not enough fee to ever get it confirmed. I wanted to pay 0.0001BTC but I've paid a total fee of 0.00001BTC. So not even a transaction accelerator can help me out with this problem anymore. My question is now, what can I do to get my bitcoins back or even get it ever confiormed?

Best regards,

Sazer


texts: Projections for reductions in price of hardware wallets

texts:
The components of hardware wallets are not very expensive (at least when purchased as scale). I understand the need to recover R&D costs and that higher sales volume will increase negotiating power with component and manufacturing providers.

Are there projections for the future prices of existing hardware wallets (such as KeepKey, Trezor and Ledger) over the next 12-24 months based on projected sales data?

When hardware wallet costs near the cost of flash drives, then usage and security for new bitcoin users (and minimal funds) should increase dramatically.


texts: How was Ethereum hard fork's replay attack was handled?

texts:
On etherum, there was a hard fork which resulted in ETH and ETC.  My reading indicates that it suffered problem of replay-attack.

Question:

How was this problem resolved for Ethereum?  In my understanding, replay-attack protection requires another hard fork, because replay-protection inherently requires making transaction incompatible among the 2 chains.  Was such fork operated?  Or does Ethereum still have possibility of replay-attack if transaction is to be made from the very old wallet (the wallet which have no associated transaction after the fork)?


texts: Do you know any download site for full blockchain header data (6) in CSV ASCII format?

texts:
do you know any download site for full blockchain header data (6 variables) in CSV ASCII format ?

I would like to enter block header data for every block from No.0 to latest into mining simulator to let students see, every nonce calculated works and any other nonce, random selected fails.

thank you


texts: Error message still returned after transaction was indeed broadcast

texts:
I use bitcoinj to create the following method to broadcast a raw transacion in testnet, and I did see on bitcoin explorer that it has been broadcast. But even the transaction has been already broadcast, it always return false message, please help me to solve this issue, I don't know if there is a problem when sync with the peer or if my broadcast method is wrong.

//sync with the peer
static WalletAppKit kit = new WalletAppKit(params, new File("."), "sendrequest-example");
kit.startAsync();
kit.awaitRunning();

//transaction broadcast method
public static boolean broadcastTransaction (Transaction tx) {
        System.out.println("Broadcast transaction: ");
        System.out.println(tx);
        try {
            TransactionBroadcast broadcast = kit.peerGroup().broadcastTransaction(tx);
            broadcast.future().get(20,TimeUnit.SECONDS);
            System.out.println(tx.getHash() + "broadcasted successfully!");
            return true;
        } catch (Exception e) {
            System.out.println("e.getMessage() = " + e.getMessage());
        }
        return false;
    }

The false message is always as following, although the transaction has been indeed broadcast.

e.getMessage() = Waited 20 seconds (plus 1985971 nanoseconds delay) for com.google.common.util.concurrent.SettableFuture@20d525[status=PENDING]

e.getMessage() = Waited 20 seconds (plus 4214583 nanoseconds delay) for com.google.common.util.concurrent.SettableFuture@38afe297[status=PENDING]


texts: How to extract maximum value from a 51% attack

texts:
If an attacker were to gain 51% of the network, they can essentially forge arbitrary transactions double spend. But that would quickly lead to a completely loss of trust in bitcoin. In fact, that would probably happen as soon as someone was suspected of having a majority.

What strategies could a majority-attacker use to extract maximum value? What could they do without detection?


texts: How do I resolve an accidental double spend?

texts:
I made a double payment to the same address mistakenly since my internet was a bit slow, and one payment has 8 confirmations. The recipient says he hasn't received it. I got this message from the transaction:

  A conflicting transaction has been detected in our memory pool. The transaction hash displayed below may change.

What can I do to resolve this?


texts: Why does Bitcoin Core, on the message verification tab, say that verifying messages signed by Bitcoin addresses "only proves the signing party receives with the address, it cannot prove sendership of any transaction." Why? And is there a method of proving sendership in Bitcoin?


texts: What is the fraction of the Bitcoin mining power that might be engaged in Selfish-Mining?

texts:
Is there an estimate for the fraction of miners engaged in Selfish Mining within the BTC network? In light of the publication The Impact of Selfish Mining on Bitcoin Network Performance (2021), selfish miners not only gain an extra (unfair) share of the block rewards but also increase the chance of forking the network and implementing double-spending attacks. To accomplish that, a group of mining pools holding ~25% of the mining power would be enough to attack the network.
I believe this should get more attention from the community since it represents a significant cut in threshold-security from the famous 51% to about ~25% of the mining power.
It seems that extra elements could cut the threshold-security even further: e.g. If the miner engaged in selfish mining spread 0-power nodes around, they could use those nodes to communicate their selfish-mined blockchain (whenever it is convenient for himself) and leverage advantage on network visibility; meaning: the selfish-minted blockchain would have more visibility then a competing & fairly-minted blockchain.
Searching around the web, I could not find an estimate for the current fraction of the BTC mining power that might be engaged in selfish mining.
Is there any strategy we could use to investigate about that?


texts: Convert an lower-cased address to a properly capitalized address?

texts:
Is it possible to take a lower-cased address like 1dice8emzmqkvrge4qc9buff9px3xaydp and convert it to the properly capitalized address of 1dice8EMZmqKvrGE4Qc9bUFf9PX3xaYDp ?

I've looked around and everything can simply tell me whether it is valid or not.  And without the correct capitalization, the address is of course not valid.


texts: How to 'attach' metadata to a bitcoin receive address

texts:
I need to generate a receive address that is directly associated with some metadata, M, that forms part of a verifiable contract.

I require that customers can verify that an address really was generated from a specific contract message, but I do not want them to have the private key to the address.

I obviously don't want to bloat the blockchain nor do I wish to use non-standard transactions. P2SH is also not possible as it is still largely unsupported by many online wallet providers.

So here is my first attempt, based on (https://bitcointalk.org/index.php?topic=108423.0) ...

# generate an EC key pair for the company
issuer_public_key = issuer_private_key * G

# create a contract message string, M
M = 'Terms of contract bla bla and also includes issuer_public_key for safety'

# generate a hash of the message
e = SHA256(M)

# create an EC point that is known to both parties
contract_point =  (e * issuer_public_key)

# generate a public key for this contract to form our receive address. Customer agrees to contract when they send BTC to receive address.
receive_public_key = contract_point + issuer_public_key

# the private key for the receive address is thus
receive_private_key = contract_point + issuer_private_key

Feedback much appreciated


texts:
Is it possible to invest in a bitcoin startup/company without being an accredited investor?
Say for example I would like to invest in coinbase.com, is this possible?


texts: BitCoin Linux Application / Proper method to set up

texts:
1 - Can I run the BitCoin daemon (before KDM is even started)?

2 - Once I've started KDM, can I then run the GUI which will attach to the daemon, so only one BitCoin 'app' actually working?

3 - Can you get a status report from bitcoin-cli, similar to the qt-app (status of catching/caught up with blocks etc...)

Following the BitCoin Install Guide , I ran the qt-app after installtion, it worked fine. I tried the daemon after and got issues with 'no cookies' / problem with rpc authorisation.  I've also stopped the qt-app, then tried the daemon, it worked fine, then tried the qt-app and it complained something was already connected to the default port.

What is the correct order of running it, note the machine is on 24/7 (minus the desktop).


texts: Electrum multisig 2of2 on separate machines and both offline(cold storage)

texts:
I am lost sending coins from these Electrum 2of2 multisig wallets. Call them mutisig1 and multisig2. Both wallets have the 2of2 heading, presumably that means they are correctly setup, they were created with their own seeds and then each used the other's seed for multisig.

I use an online watch wallet(using xpub of multisig1 wallet) to create an unsigned send txn, save it to a usb drive.
load unsigned txn into multisig1  , sign it , save and export to usb drive.  (what is the difference between save and export ?)
load signed txn into multisig2. There is no sign option(greyed out) then what ?

I tried 3 methods to send the coins , all 3 different, all 3 worked(confirmed sent), at least 1 was certainly wrong(only 1 sig). Now I'm worried ! I conclude that this does not achieve 2of2 in electrum or I have screwed something up. You can pretty much do anything as long as you have at least 1 sig, it will confirm.

Test1

Online watch wallet-send txn , export to usb
Offline multisig1 wallet-load unsigned txn,  sign, save, export
Offline multisig2 wallet- load unsigned txn, sign, save, export(this overwrites the prev signed txn file from multisig1 wallet )
Load signed txn file from step 3 onto watch wallet and broadcast

Test 2
l
Only signed on 1 multisig wallet and then broadcast from watch wallet. (sent and confirmed only 1 signature !)

Test3

and 2. are the same, but 3. I just loaded the signed txn on multisig2 and then saved and exported it back. Sign button was greyed out.


texts: See the balance without load the transaction history

texts:
Let's say I have a wallet.dat with several transactions, is there a way to see only my current balance without load all transactions in the wallet.dat?
I would like to achieve something like this because that would be lighter to load on my computer.


texts: Can I use same bitcoin address for Mt.Gox deposit multiple times?

texts: They say they will generate new address for each deposit. If I want to split my bitcoin transaction in multiple parts but send one after another, can I use the same address more often?


texts: In BitcoinJ, do I need to run downloadBlockChain() again after adding a new key?

texts: I added a Wallet instance to PeerGroup instance and executed downloadBlockChain() method. Now if I add a key(s) to that wallet, do I have to execute downloadBlockChain() again to get a current balance including a new key or will it show a right balance automatically, assuming the new key has some balance?


texts: How big is the Bitcoin network in terms of total number of computers (peers, clients) that are connected together? Are there any network statistics or historical size data available?


texts:
The Ethereum ERC20 token is also the contract. The token can never live without the contract. The name of the contract is the name of the token. In the code, the keyword is contract and not token.

I may hold 4 ETH but does that mean I'm holding 4 ETH contracts? If that is the case, why call them tokens at all?

Is everyone exchanging tokens or contracts?

For an ICO, there is an ICO contract created to limit supply and issue tokens. If the contract is the token and the ICO contract goes away after the ICO, how do the tokens exist?


texts:
In my Bitcoin Folder I found on my old computer,theres also files of  aprox. 130 Mb .dat files. I have now, like I was told dumped the wallet.dat into my new installation of Bitcoin Core, and its running.

Will I need those blk000xx.dat files for any reason ? Are there any cions in them, or information of any value ?


texts: Making Bitcoin Core 0.12.0 maximize by bandwidth

texts:
Bitcoin Core 0.12.0 added many bandwidth (e.g., maxuploadtarget) and rate limiting (e.g., with maxmempool) features.

I have maxuploadtarget set to 0 (default; unlimited), yet I used to get several gigabytes of traffic each day. Now I only get a few hundred. Why?

What must I do to make Bitcoin core maximize my bandwidth?


texts: How do bitcoin verifies block hash after new hash have been submitted by Miners?

texts:
I want to know how at the end of Bitcoin server block hashes are verified after it has been submitted by a miner.  Do they already have a previously calculated block hash DB or something else?
I m new to Bitcoin. Pardon my little  knowledge
Thanks


texts: Given only a private key, is it possible to see if it has unspent bitcoin?

texts: I understand a "wallet" to be a private key and a collection of associated public keys. But if I was to be given only a private key, would I be able to determine if it had any associated addresses/public keys that had unspent bitcoin in them? If so, how?


texts: Does kraken.com charge fees when an order is cancelled?

texts:
Do you pay the fees if you order a transaction then cancel/replace it?
What if the order has been partially fulfilled before cancelling?

In other words, do you pay fees for orders or for transactions?

See the same question for e-BTC


texts: Find message attached to Bitcoin transaction?

texts: Given a txid, can I find out the message/comment the transaction was attached with by the sender?


texts: BitcoinCore walletnotify before blocknotify?

texts:
I want to use bitcoind's walletnotify and blocknotify features. The question is:

Is blocknotify script always triggered after walletnotify script?

Imagine, I have an unconfirmed transaction in my wallet and I wait for a new block to arrive. When bitcoin node gets a new block, it has to fire both walletnotify for the first confirmation of my transaction and blocknotify for the block. Are all walletnotify events always fired before a blocknotify event?


texts: Creating An Altcoin: How to Lower or Increase Confirmation Times?

texts:
When Creating an Altcoin for fun, what variable/attribute do I change in main.cpp file to increase/lower the time it takes for confirmations to take place?

Also can the confirmation times be changed again after coin is re-compiled/re-built?

Thanks.


texts:
I've some utxos with a address. I use CreateRawTransaction to make a transacton. But this method need a txid filed, I've searched a lot to get the txid from the address, but I didn't find any.

So is it possible to make transaction without wallet programmatically？

Note:I use the command line only, non-wallet distribution, I just want to create, sign and send transactions with command-cli or rpc.


texts: How to broadcast a transaction without using third parties

texts: Without running a node, just via terminal, can you build and complete the broadcast of a transaction without using a third party PushTx API? How do I connect directly to the network? Is it possible? What do you need?


texts: Can anyone initiate a Blockchain transaction into the mining pool?

texts: Let's say user A has public key P and corresponding private key P'. Can someone else initiate a transaction for public key P with some wrong private key, let's say P''? Once this goes to the memory pool, miners will see that it is not signed with correct private key P' and will reject the transaction. Does it happen this way? Or is it that I can't initiate a transaction at all with wrong key?


texts: old wallet.dat from 2013/14 with some btc not confirmed or in mempool

texts:
Found a wallet.dat from 2013/14 with some btc received from a pool as i did a bit of mining.  4 received transactions in latest bitcoin core wallet but 0 confirmations and says not in mempool.  Balance is 0. TXs not found on Blockchain.  The address comes up but shows only a recent tx i tried on the wallet just to see if it worked.  the old txs are nowhere to be seen. Tried rebroadcasting but came back with 'missing parents'

some help would be greatly appreciated

15m5h2E3L4Hy4t7qnZn1ooVmegCRNdkezB  this is the address concerned.


texts: How to edit the label of an existing address exactly like in bitcoin-qt but instead using RPC calls?

texts:
I am trying to edit the label of a bitcoin address in my wallet outside of bitcoin-qt. Currently I only know of 'setaccount' but it results in two addresses after editing one, it assigns a new address to the old label for some reason?

Does anyone know if there is a way to accomplish my goal?


texts:
Basically for this question I need a confirmation that all of my listed assumptions are fairly accurate.

The bitcoin network measures how much time it took to create the last 2016 blocks in a blockchain. If it took significantly more than 2 weeks, the challenge difficulty is reduced. If it took significantly less than 2 weeks, the difficulty is increased.

Who performs these measurements? Every miner for themselves? I assume, since they operate on the same algorithm, they automatically change the goal for their algorithm from time to time without having to verify their assumptions with anyone.

For example, for some time a certain miner has been trying to provide responses to challenges so that the hash(challenge+proof) has 40 leading zeros.

After each new block is being inserted in the blockchain, a miner measures the time it took to produce last 2016 blocks.

If the measured time is higher than a certain treshold, difficulty should decrease.

From then on, the miner simply starts submitting proofs of work that result in 39 leading zeros.

The miner is counting on the fact that the other miners had the same conclusion and that they will accept his answer, his proof of work?

Even though the miners didn't have an official agreement - "From now on, we are all solving an easier task. Ok? - Ok! - Lets go!"


texts: Bitcoins missing following wrong bank account number entered

texts:
In 2019 I commenced trading with an online Bitcoin trader called Assetgates, who had contacted me via my mobile phone.
Money was transferred from my bank to a Kraken account, then to Assetgate in the form of Bitcoins to trade. a broker contacted me daily and transactions were made be the said person.
By March I had accumulated $160,000 which I decided to withdraw.My broker transferred me to another person who took me through the process of transferring the said monies to my Kraken account. In the process of the transfer the Kraken bank account number had the K missing off the end.
My broker then informed me that my money was with the Miners who would give it back if i forwarded 17% (£22500) which was money I did not have.
I was then informed that the miners would divide the money between themselves, and I would receive nothing.
Can you advise me if there is any way I can trace this money to see infect where it ended up?


texts: How is a locking script reliably detected as a P2PKH script?

texts:
I've taken this example from a p2pkh guide:
1976a9145fb0e9755a3424efd2ba0587d20b1e98ee29814a88ac

This is broken down into:
19 - byte length of the following unlocking script
76 - OP_DUP: Duplicates the top stack item.
a9 - OP_HASH160: The input is hashed twice: first with SHA-256 and then with RIPEMD-160.
14 - (20 bytes) length of the following public key hash
5fb0e9755a3424efd2ba0587d20b1e98ee29814a - public key hash of funds receiver
88 - OP_EQUALVERIFY: Returns 1 if the inputs are exactly equal, 0 otherwise. Then runs OP_VERIFY which fails and marks the transaction as invalid of the top stack value is false
ac - OP_CHECKSIG: The entire transaction's outputs, inputs, and script are hashed. The signature used by OP_CHECKSIG must be a valid signature for this hash and public key. If it is, 1 is returned, 0 otherwise

How does Bitcoin determine that 0x14 is the length of the following public key hash, rather than interpreting this byte as an opcode with the value 0x14 (20 decimal)? Is 0x14 special and will never be assigned to any opcode? I don't see any special handling of this value in the CScript::HasValidOps() and GetScriptOp() routines here.
Is there a magic marker to detect P2PKH scripts?


texts: Why does it take 15 minutes for my Bitcoin client to start?

texts: I use Ubuntu 11.10 and have recently installed the standard Bitcoin client 0.40. But the GUI only appear around 15 minutes after started. My machine is an AMD64 Athlon 4600x2 with 6GB RAM. Is this normal? (I don't think so) Any idea?


texts:
There seemed to be great demand for multi-siganture transactions to be provided, but they don't seem to be so popular now that they are available.

What percentage of transactions are multisig since their release?


texts: Are there any privacy benefits in using a separate wallet in Bitcoin Core to separate myself from my service?

texts:
I currently run Bitcoin Core with the following wallets loaded in:

hot.dat. Contains the smallest possible sum of Bitcoin. Unencrypted and used by myself for various personal Bitcoin purchases, and I intend to have it double as the wallet for my Bitcoin-based website. (Unless you tell me a good reason not to.)
lukewarm.dat. Contains more than the "hot" wallet, but still not much compared to cold.dat. Encrypted with a long passphrase, but which is located on the same computer in a text document. I recon that it will stop at least automated malware which simply checks for wallet.dats and merely "sends them home". It of course won't stop somebody from manually finding the text document on my machine and figuring out that it's the passphrase to use.
cold.dat. Contains the vast majority of my satoshis. Encrypted with a long passphrase (partially stored on the same computer) with a bunch of additional parts with "hints" to myself rather than explicitly spelled out. This passphrase has never been entered to unlock the wallet outside of the dedicated Linux computer where it was created. (Not this machine.)

I'm aware that many would not consider my cold.dat to be a "cold wallet", but I thought the naming scheme fit well enough. The reason I don't use a truly "cold" wallet (where it's not stored on a "live" computer even encrypted) has to do with me fearing losing the file or having a fire or getting it seized more than I fear somebody first hacking into my machine and then somehow figuring out my complicated passphrase scheme. I consider that so unlikely that it is far more likely that I would lose access to it in other ways.
Now I wonder if I should be having a separate "service.dat" wallet dedicated to my new service, or if I can just generate new receive addresses for my existing hot.dat and use those. Is there any privacy benefit in me doing that? Or would I just be wasting yet another transaction fee to send over some satoshis from my hot.dat to my potential "service.dat"?
What if somebody who I do private business with knows who I am (because I have to give them my home address) and when I've paid them using hot.dat, those "inputs"/"outputs" are reused for my service, and suddenly they can associate me, the individual, with my service? And would that change at all if I used a separate "service.dat" wallet for the service? Won't it be the same "track" either way?
It's not something illegal or immoral. I'm simply trying to avoid any association between myself and the service, plus I'm also curious about this in general.


texts: Why do we inverse the hash of the blockheader?

texts:
Let's pick this example blockheader-hashing in Python:

from hashlib import sha256
import hashlib
header = "0000002066720b99e07d284bd4fe67ff8c49a5db1dd8514fcdab610000000000000000007829844f4c3a41a537b3131ca992643eaa9d093b2383e4cdc060ad7dc548118751eb505ac1910018de19b302".decode('hex')
print sha256(sha256(header).digest()).digest()[::-1].encode('hex')
// result is 00000000000000000020cf2bdc6563fb25c424af588d5fb7223461e72715e4a9

I know that it's part of the protocol and otherwise, a block will not be accepted, but:

Why do we not accept a hash that ends with all those zeros? Is it because it's easier for a program to calculate if hash < expected_hash?
But in this case, I don't understand why do we do not simply accept a hash sha256(sha256(header).digest()).digest().encode('hex') that is lower than the expected hash? The probability to get that should be as high as the inversed one.

So what's the reason of inversing it?


texts: Why do transaction fees exist in the Bitcoin blockchain if miners get rewarded with newly created bitcoins?

texts: My question is why transaction fees exist, even though the miners would still get rewarded with the newly created bitcoins when/if they mine a block. Miners will rather verify transactions with a higher transaction fee to eventually receive the fees themselves, but what if there were no fees involved and all the transactions would be verified without other considerations. The only reason I can think of is that with no transaction fees, when all the bitcoins are mined, there will be no more incentive for the miners and the network will fail. Is there another reason or is that it?


texts: Are time, timereceived and blocktime in UTC?

texts:
I read around about the differences between time, blocktime and timereceived, but one question remains. Although I assume all times are UTC, I haven't seen that mentioning specifically anywhere.

Does anybody know which timezone the times in the bitcoin blockchain are formatted in? And does this also account for timereceived, or is that local?


texts: Given an altcoin, how to find its mining pools?

texts:
I wonder if it can be possibile to find all pools for a given altcoin.

For example, if an altcoin X has an official pool P and its official pool crashes or its not working, how we can find all the pools for the given coin?

It is supposed that the other pools aren't indexed on search engines.


texts: What are the consequences from the leak of xpub and child private key?

texts:
Let's say the following keys are leaked:

Extended public key derived from path 44'/60'/4'
Leaked child private key from path 44'/60'/4'/0

Does that imply all the child private keys of the root 44'/60'/4' can be computed? Looking and reading at the BIP32 and BIP44 - that doesn't seem to be the case. But wanted to confirm.

Also, if we know that it doesn't cause the sibling keys to be derived, then can I go and safely use the following public key of path 44'/60'/4'/1 without any worries?


texts:
I had received bitcoins before my wallet was fully synchronized and it took several days for it to finish the process, so I decided to deposit the bitcoins in another wallet. Now I can see they are "on deposit", but they do not show up in my other wallet. How can I move them to my wallet or use them?
Thank you!


texts: How to delete last n blocks / roll back to specific block number in Bitcoin Core? (Like `monero-blockchain-import --pop-blocks n`)

texts:
I have Bitcoin Core's bitcoind running and synced in a VM. Now I want to clone the VM and run one of the various hard forks (such as Bitcoin Cash) in the clone. The plan is to roll back my copy of the blockchain database in the clone to the last block shared by the two chains (e.g. block number 478558) and then start the fork's bitcoind to sync the rest.

But I can't find the Bitcoin Core equivalent to Monero's --pop-blocks n, which deletes the last n blocks. Any ideas?

(I'd really like to avoid reimporting or even just reindexing the full blockchain, because my computer is quite slow and it will also waste lots of space compared to a CoW snapshot sharing most of the data between the two VMs.)


texts: How to find out addressHeader p2shHeader

texts:
I am trying to find out the location or a method (may be) for addressHeader and p2shHeader parameter for any altcoin. The following list contains these 2 parameters for few coins but I am unable to find the source of these.

addressHeader = 30  Digital coin
addressHeader = 25; Blackcoin
addressHeader = 76; Dash
addressHeader = 30; Dogecoin
addressHeader = 0   Crown
addressHeader = 14; Feathercoin
addressHeader = 25; NuBits
addressHeader = 63; NuShares
addressHeader = 68; Uro
addressHeader = 30; Verge

p2shHeader = 5;     Digitalcoin
p2shHeader = 85;    Blackcoin
p2shHeader = 16;    Dash
p2shHeader = 22;    Dogecoin
p2shHeader = 5;     Crown
p2shHeader = 5;     Feathercoin
p2shHeader = 26;    NuBits
p2shHeader = 64;    NuShares
p2shHeader = 5;     Uro
p2shHeader = 33;    Verge


texts:
I want to use ZebPay since I am from India but this question is applicable to all Bitcoin waletts like CoinBase. Can I sell directly from my wallet ?

For example if I have 1 BTC in my wallet can I sell it directly from there and get the funds in my bank account ?

Or do I have to wait for some third party to buy my bitcoins and then I can get paid ?

In short, can I sell to ZebPay or CoinBase directly for USD ?


texts: Does an SPV bloom filter get applied to full blockchain or just new transactions

texts:
When an SPV client starts up with no state, connects to a full node and sets a bloom filter what messages will it receive?

Will it only get new transactions that match its filter or is there some way to also get the full node to supply all previous blocks that match the filter?


texts: What is the estimated price of Bitcoin which will push miners to stop mining if its price dropped to uneconomical level ?

texts: What is the estimated price of Bitcoin which will push miners to stop mining if its price dropped to uneconomical level?


texts:
I am trying to send BTC with Armory. Everything works just fine until I have to hit the "send"-button. Then it just does nothing.

I have had this problem before (I had even posted it here) and solved it by clicking the same button a billion times. Now this isn't helping anymore. I am using 0.92-3 beta.

Any ideas?


texts: Can you send a transaction from non-native segwit to native(bech32) segwit address?

texts:
Let's say I have a wallet with a non-native segwit address (prefixed with 3- like multisig).

Can I send my utxos from this address to a native segwit (bech32) address?


texts: When a Ripple-Gateway charges a fee for third parties exchanging their IOU, how is it determined who pays the fee?

texts: When a Ripple-Gateway charges a transit fee for third parties exchanging their IOU, who pays the transit fee?


texts: With the right technology, could the entire blockchain be rewritten?

texts:
Imagine that someone had access to an alien super computer such that they could mine any block in nanoseconds. At that point, could that person create a chain with the same BTC genesis block, generate any/all the blocks and transactions they want, to the point where this new chain had a greater cumulative difficulty than the current chain? And if that person did this, would the network accept this chain, thus erasing the past 10+ years of BTC?
I realize the computational power to do this is theoretical, like this question. However, I still wonder what, if any, safe guards are in place to prevent something like this?


texts: How does a BIP70 url look like? I want to send my email to the person I'm sending my coins to.

texts:
I'm trying to build an application that takes bitcoin and also an email. But when you send bitcoin you cannot send a message attached to it. Supposedly BIP70 solves this problem. How does a BIP70 URI look like? Example: I sell digital tickets that I email to my customers. My customers only have my bitcoin address. When they send Bitcoin to my address, how can they also send me their email address so I can email them the "digital ticket". Don't I have to have my URI something like this:

bitcoin:12A1MyfXbW6RhdRAZEqofac5jCQQjwEPBu?amount=1.2&message=buytickets@gmail.com


texts: How can I compile bitcoin on debian 7.x Wheezy? Missing libmemenv.a

texts:
In the bitcoin leveldb branch, the file libmemenv.a is missing. Because the debian leveldb package does not include it, bitcoin will not compile on debian systems.

Is there any workaround? Will you all be including this library in an upcoming release?


texts:
Dears,
If the PHP script and the Bitcoin wallet are on the same computer, does encrypting the link is necessary? like turn ssl on:rpcssl=1


texts: What are the minimum hardware requirements for mining in a bitcoin pool? Note that I'm not looking for profitability, this has been answered numerous times. I'm more into setting up an old computer to learn how things work. But I guess there are minimum hardware requirements to be able to  mine at all, e.g. being able to transfer blocks when a hash is found and a new block gets the attention. Are there any limits in the pools? Pools might not want participants that are so weak that they just create administration? If so, what is the minimum hash rate level, or is there another figure limiting pool access?


texts: I see on the wiki that they're the 2nd Gateway, but don't see anything about it on their site.


texts: What happens if Bitcoins are sent to a wrong, randomly generated address?

texts:
I am new to Bitcoin and I confused creating a New Address for receiving and sending payments.

Here's what I did:

Generated a random Bitcoin Address (using www.bitaddress.org)
Created a New Address in my wallet (added it to "Addresses", for SENDING payments - I simply thought this would be my address for receiving BTC)
Purchased BTC in an online exchange and send the money to that address.

What happens to the coins now? Are they lost forever or waiting for someone lucky to get this address to receive payments (if it doesn't exist yet)...? What can I do to get them back, if anything?
Also, is there any way to assign a randomly generated address to my addresses for receiving payments?

Please help.


texts: how does bitcoin know which one is utxo?

texts:
Let's say John gave 5 BTC to me. So, John took his unspent outputs and put it into inputs to create a transaction.  Let's say John already had a transaction which was holding exactly that amount of BTC.
Now, How can John not spend 5 BTC anymore ?  The output John used to give me 5BTC is still on Blockchain. So, does node go to that output transaction and mark it as spent ? how does it mark it as spent?


texts: Can't start bitcoind after wallet encryption (Bitcoin Core)

texts:
pretty new to the Bitcoin world!

I downloaded Bitcoin Core and got everything up and running.  I then attempted to encrypt my wallet, and after successful encryption can no longer start bitcoind.  When I run bitcoind on the terminal I get the response:

Incorrect or no genesis block found. Wrong datadir for network?

Looked all over but can't find any solutions.  I have a feeling this is a really easy fix but I just can't figure it out.


texts: How specifically is transaction history modeled in blockchain blocks?

texts:
I understand that each block on the Bitcoin blockchain contains a list of transactions, but let's assume (for the sake of this question) that the block in question contains only a single transaction--and that this particular transaction has a history of previous transactions (i.e., it was not a coinbase transaction). How would I figure out which block holds this single transaction's previous transaction(s)? I know that each transaction contains the hash of the previous transaction--but how do you find that hash without looking into every block on the blockchain? In other words, how can I quickly discern a transaction hash chain for a given transaction ID? Any links to explanations or previous questions would be appreciated--I tried searching and haven't seen anything that answers my question to my satisfaction.

Thank you.


texts: Do mixers rely on other users, or can one mix his or her own bitcoins alone, such as by sending them to one's own addresses?


texts: Address creation in standard client - random library?

texts:
Is the random library used by the standard client in any way deterministic, or can one count on it being truly random?

For example, often random libraries are initialized with seed value of the current time, like in C++:

srand(time(NULL));

But if someone was to iterate over reasonable ranges of time when a client started, eventually one would use the same seed value, and thus be able to generate the same addresses.

Is the random library used by the standard client vulnerable to such an attack, or does it also use some other variables that are unpredictable (say, temperature of the processor down  to such decimal places it becomes an unpredictable noise)?


texts: Is my cgminer (scrypt) working / Mining on middlecoin pool

texts:
I'm trying to mine on the middlecoin pool using the following command:

  cgminer --scrypt -o stratum+tcp://middlecoin.com:3333 -u
  1C7Ubg5VxvJyXYBT6neNVFgUVdgq1Kiy72 -p asdf

and I do get the screen below, but I'm not seeing my bitcoin address appear on: http://www.middlecoin.com/allusers.html (and I've waited a couple of hours)

 cgminer version 3.7.2 - Started: [2014-01-31 13:03:27]
--------------------------------------------------------------------------------
 (5s):3.725K (avg):3.694Kh/s | A:0  R:0  HW:0  WU:3.4/m
 ST: 2  SS: 0  NB: 398  LW: 1943  GF: 0  RF: 0
 Connected to middlecoin.com diff 1.02K with stratum as user 1C7Ubg5VxvJyXYBT6ne
 Block: 1e7643a6...  Diff:1.17K  Started: [14:56:27]  Best share: 313
--------------------------------------------------------------------------------
 [P]ool management [G]PU management [S]ettings [D]isplay options [Q]uit
 GPU 0:                | 3.703K/3.694Kh/s | A:0 R:0 HW:0 WU:3.4/m I: 8
--------------------------------------------------------------------------------

 [2014-01-31 14:51:52] Network diff set to 25
 [2014-01-31 14:51:52] Stratum from pool 0 detected new block
 [2014-01-31 14:51:56] Network diff set to 26
 [2014-01-31 14:51:56] Stratum from pool 0 detected new block
 [2014-01-31 14:52:04] Network diff set to 343
 [2014-01-31 14:52:04] Stratum from pool 0 detected new block
 [2014-01-31 14:53:46] Network diff set to 55
 [2014-01-31 14:53:46] Stratum from pool 0 detected new block
 [2014-01-31 14:54:08] Stratum from pool 0 detected new block
 [2014-01-31 14:54:32] Network diff set to 1.17K
 [2014-01-31 14:54:32] Stratum from pool 0 detected new block
 [2014-01-31 14:55:19] Stratum from pool 0 detected new block
 [2014-01-31 14:56:27] Stratum from pool 0 detected new block

When I exited, it showed :

...\cgminer-3.7.2-windows>cgminer --scrypt -o stratum+tcp://middlecoin.com:3333 -u 1C7Ubg5VxvJyXYBT6neNVFgUVdgq1Kiy72 -p asdf
 [2014-01-31 15:49:18]
Summary of runtime statistics:

 [2014-01-31 15:49:18] Started at [2014-01-31 13:03:27]
 [2014-01-31 15:49:18] Pool: stratum+tcp://middlecoin.com:3333

 [2014-01-31 15:49:18] Runtime: 2 hrs : 45 mins : 51 secs
 [2014-01-31 15:49:18] Average hashrate: 3.7 Kilohash/s
 [2014-01-31 15:49:18] Solved blocks: 0
 [2014-01-31 15:49:18] Best share difficulty: 313
 [2014-01-31 15:49:18] Share submissions: 0
 [2014-01-31 15:49:18] Accepted shares: 0
 [2014-01-31 15:49:18] Rejected shares: 0
 [2014-01-31 15:49:18] Accepted difficulty shares: 0
 [2014-01-31 15:49:18] Rejected difficulty shares: 0
 [2014-01-31 15:49:18] Hardware errors: 0
 [2014-01-31 15:49:18] Utility (accepted shares / min): 0.00/min

 [2014-01-31 15:49:18] Work Utility (diff1 shares solved / min): 3.53/min

 [2014-01-31 15:49:18] Stale submissions discarded due to new blocks: 0

 [2014-01-31 15:49:18] Unable to get work from server occasions: 0

 [2014-01-31 15:49:18] Work items generated locally: 2688
 [2014-01-31 15:49:18] Submitting work remotely delay occasions: 0

 [2014-01-31 15:49:18] New blocks detected on network: 545

 [2014-01-31 15:49:18] Summary of per device statistics:

 [2014-01-31 15:49:18] GPU0                | (5s):3.741K (avg):3.703Kh/s | A:0 R:0 HW:0 WU:3.5/m
 [2014-01-31 15:49:18]


texts:
I encountered a error whilst downloading Bitcoin-Qt on my Macbook version 10.6.8; it says "Failed to read block"
How do I fix this error without losing the bitcoins currently in my wallet?
Your assistance will be greatly appreciated.


texts: I bought 200 ($700 worth) bitcoins in 2012, and I found them last week. Now, my wallet says they are worth $2371959.00 apparently. Is this a scam or do I need to sync my wallet? The computer is pretty old so I'm not sure if it is a virus. Has anyone had this issue?


texts: What will cause BTC/USD to shift substantially?

texts:
Possible Duplicate:
  What factors affect the value of a Bitcoin?

It's been hovering at about $5/BTC for a few months now, slowly eeking upwards. What would cause a significant spike or drop?

Hacking and theft will, presumably, come down as more players get stable. As exchanges rise, liquidity should grow.


texts: I am reading about the Merkle tree, I've read that in a block we store just the root of the tree. To check if a ttransaction is included in the Merkle tree we need to use the transaction's Merkle path. The question is where the Merkle tree is stored? How would a node given a path check if the leaf belongs to the Merkel tree?


texts:
In Merkle tree, leaves are actual transactions and internal nodes are hash of their childrens. In the Bitcoin paper, Satoshi talks about pruning branches in the Merkle tree to save storage space.

Under what conditions can be the branches pruned? I understand that the Merkle root is used in finding POF for the block. Are there any situations where all nodes in the Merkle tree are pruned except the root?


texts: Is it possible to speed up block chain syncing with a miner?

texts:
Syncing the client with the network can take some time. As I have to do this fairly often, it quite bothers me, especially when on slow devices. (A Pi can't do it in a week.)

I don't know exactly what the client does when syncing. Does it verify the block hashes? Transaction hashes as well? If it does hashing, a miner should be able to speed it up. I noticed periodic CPU bursts of the client, so that's probably when the hashing is done.

So, I happen to have one of those little Block Erupter USB Miners. Is it possible to setup one of these to speed up syncing?


texts:
Currently Bitcoin blocks are limited to 1MB and each block seems to hold roughly 1000 transactions assuming each transaction is 1KB.

Much of a transactions size seems to be caused by Bitcoin's built-in scripting system to facilitate complex transactions.

Would Bitcoin benefit from a deliberately primitive blockchain, one that can only records the input addresses and output addresses?

My thinking is that for most transactions you would only need 1 input and 2 outputs. So you could reduce the transaction size from 1KB to about 100 bytes. That would increase Bitcoin's Tx/s by 10 times I'm assuming.

What's more, since the Blockchain is primitive by design it couldn't handle anything like Escrow or any other kind of transactions. This would encourage people to do those activities before they record their transaction on the Blockchain which would mean there would be less demand on the Blockchain for transactions.

These are just ideas I had, if anyone could disprove them that would be cool too!


texts: Will more hashes per second increase bitcoins per hash per second?

texts:
I read this article:

  We have paid 0.034 BTC for the 10 GH/s ... Yesterday we have received our first daily payout and it was exactly 0.00041279 BTC ...   Doing a quick calculation has shown that if the Bitcoin network difficulty remains the same and the daily payout is also the same as the one we got the first day we are going to need a little over 82 days to get back what we have spent for the mining contract.

In this case BTC per GH/s is 0.00041279/10 BTC/(GH/s). All of this is in one day, but for simplicity I removed day from the units.

Will buying more GH/s increase BTC per GH/s (in one day)? Since there is more power solving the problem, and there would be more probability to solve the problems?

How could I calculate decrease of BTC/day vs time with a fixed hashing speed?


texts: What does script operation "OP_IFDUP" do?

texts:
According to the wiki page, OP_IFDUP will duplicate the top of the stack "if the input is true or false".  It seems to me that everything is true or false when interpreted as a boolean.

According to the source code:

case OP_IFDUP:
    [...]
    valtype vch = stacktop(-1);
    if (CastToBool(vch))
        stack.push_back(vch);

That suggests the wiki is incorrect.  What would be a better way of wording it, and what is the operation for?


texts: What are the risks of using Strongcoin.com as an online wallet?

texts:
Strongcoin claims it is "The Safest way to store your Bitcoins. The only Bitcoin e-wallet service that's not vulnerable to security breaches. Your Bitcoin keys are encrypted in the browser."
As I understand it, with their system your private keys are essentially encrypted by your browser before they are sent to the website. They also appear to have a method of creating an encrypted paper copy of your wallet so you can restore your wallet if the website disappears.
Even so, it seems you're still potentially vulnerable if you access your wallet from an infected computer (i.e. through keystroke loggers and more advanced logging techniques).
What other risks are there in using such a service?
Note: I have not used Strongcoin, and have no affiliation with them in any way.


texts: Is there a way to buy or sell Bitcoins for Iceland Kronas?

texts: Say I was living in Iceland and wanted to convert my local currency to Bitcoin and back. What are my options?


texts: If I held fiat currency, instead BTC, on MT Gox, would I get paid sooner/more?

texts:
If I held currency on Mt. Gox, but not actually bitcoins, am I in a different situation to those who held bitcoins? For example, if I had $700 AUD but 0 BTC. I can't get any information regarding this online and do not think contacting Mt. Gox would be helpful (nor possible).

Related, but concerned about BTC held in Mt. Gox rather than fiat: I have/had 31 bitcoins on MtGox; What are my options now?

Thanks


texts: Bitcoin raw transaction with manually created redeem script

texts:
I am running bitcoin in regtest mode with 2 nodes bitcoinNode1 and bitcoinNode2.I have created a redeem script by writing the opcodes and converted into hex form using btcc.

HP-ProBook-440-G4:~$ btcc OP_IF OP_SHA256 a967bf5e8ca09e059d6bb7a3efa8f62190284649d3eab773518827164ac481fb OP_EQUALVERIFY OP_DUP OP_HASH160 f5fb6147ff889a392211d0f0831a71137bedbff1 OP_ELSE OP_200 OP_CSV OP_DROP OP_DUP OP_HASH160 cac5d03956494ffc17f78ea7b71189abf7f3593d OP_ENDIF OP_EQUALVERIFY OP_CHECKSIG

O/p: 63a820a967bf5e8ca09e059d6bb7a3efa8f62190284649d3eab773518827164ac481fb8876a914f5fb6147ff889a392211d0f0831a71137bedbff167064f505f323030064f505f4353567576a914cac5d03956494ffc17f78ea7b71189abf7f3593d6888ac

Now i am trying to create a raw transaction using the redeem script.

HP-ProBook-440-G4:~$ bitcoin-cli -regtest -datadir=./bitcoinNode1 -conf=./bitcoinNode1/bitcoin.conf -rpcuser=user1 -rpcport=19001 createrawtransaction "[{\"txid\":\"818978d31bf63158612d080c4a934a78a52f52f7bc797cc1f84f6ca8cc4b2dea\",\"vout\":0}]" "[{\"63a820a967bf5e8ca09e059d6bb7a3efa8f62190284649d3eab773518827164ac481fb8876a914f5fb6147ff889a392211d0f0831a71137bedbff167064f505f323030064f505f4353567576a914cac5d03956494ffc17f78ea7b71189abf7f3593d6888ac\":0.01}]"

But i am not able to create as it says invalid bitcoin address.

Should i convert the redeem script into p2sh? If yes can you please suggest how to create p2sh and do raw transaction with that p2sh?


texts: How does BitPay manage to confirm transactions so fast (less than a minute)?

texts:
I believe it takes about an hour for 6 confirmations. (Edited from David Schwartz's comment)

However, when I purchased some stuff from merchants who used BitPay, the payment/orders were confirmed in like 20 seconds or so?
Since BitPay is confirming the order before 6 confirmations, how does it protect itself from double spending attacks?


texts: Send bitcoin with bitcoin core without syncing to network

texts:
I want to use bitcoin-core just for sending bitcoin from my address to another destination address. i don't need the huge history information of blockchain. In fact, I want to run a light-weight bitcoin-core service in my local machine and just use its commands related to create, sign and send transaction. Is it possible without syncing to blockchain network and downloading blocks?

Thank you in advance

Reza Hedayati


texts: Is there an opensource crypto-currency exchanges engine?

texts:
I'm looking for an opensource crypto-currency exchange engine.

My preference would be for something easy to use like joomla or drupal. My exchange setup needs support for alt-coins and bitcoin.

I have discovered intersango myself. However, sql file is corrupted, there is no creation of tables and import does not work. Plus it is bitcoin exchange only (and I need alt-coin support). Site of this exchange with "invites only", registration is closed.

Is there something super-simple that I can use to get started?


texts: can I use bit coin to pay my overseas customers

texts: I have a business where I have to pay customers on other countries , I want to have the ability to transfer my funds to a bank in another country with out having to pay the high bank fees for transferring funds


texts: What site should I use to create a Bitcoin wallet?

texts:
I wanted to create Bitcoin wallet but I saw there are a lot of websites or software to create it. It's not like paypal.
I am thinking to chose Blockchain. Is it good? How to check if it's legal in my country?


texts: What do i do with Bitcoin? How to start my Bitcoin?

texts: I heard a little bit about Bitcoin and people earning money from it. How do i start my Bitcoin. I am very new to this.


texts: How to run a private bitcoin network with low difficulty?

texts:
I want to test and develop an open source mining pool. I don't have access to an ASIC miner or GPU, so I have to use my CPU to simulate mining and see how the pool really works.

The problem is the bitcoin testnet difficulty is so high and the CPU can't mine, produce blocks and get reward. I need a low difficulty private bitcoin in order to test the mining process. How can I achieve that?


texts:
Will I, or anybody have more capabilities with a Lightning Node, that is CPU or GPU Powered?
For instances a more powerful computer vs Raspberry Pi’s


texts:
I installed bcoin and I get this error about the version:

$ node -v
v8.2.1
$ npm -v
5.3.0
$ bcoin
/usr/lib/node_modules/bcoin/lib/db/backends.js:26
    throw e;
     ^
Error: The module '/usr/lib/node_modules/bcoin/node_modules/leveldown/build/Release/leveldown.node'
was compiled against a different Node.js version using
NODE_MODULE_VERSION 48. This version of Node.js requires
NODE_MODULE_VERSION 57. Please try re-compiling or re-installing
the module (for instance, using `npm rebuild` or `npm install`).
    at Object.Module._extensions..node (module.js:598:18)
    at Module.load (module.js:503:32)
    at tryModuleLoad (module.js:466:12)
    at Function.Module._load (module.js:458:3)
    at Module.require (module.js:513:17)
    at require (internal/module.js:11:18)
    at bindings (/usr/lib/node_modules/bcoin/node_modules/leveldown/node_modules/bindings/bindings.js:76:44)
    at Object.<anonymous> (/usr/lib/node_modules/bcoin/node_modules/leveldown/leveldown.js:4:46)
    at Module._compile (module.js:569:30)
    at Object.Module._extensions..js (module.js:580:10)

any ideas why?


texts: bitcoin dust spamming - could the blockchain be rendered useless?

texts: My concern isn't with individual bitcoin users but governments, what if a government spammed the network with say $1 Billion dollars worth of tiny dust transactions, including fees? The backlog of unconfirmed transactions would seem to effectively render the blockchain useless at that point and people would no longer have trust in or want to wait for transactions to confirm. This seems like it could be a major issue for the protocol...are their any defenses in place currently for some type of attack like this?


texts: What is the difference (or relation) between a Bitcoin "Block" and a GPU workunit called a "Block"

texts:
I'm looking at OpenCL and GPU programming and see the term "Block" used to describe a unit of work sent to a GPU.

What is the relation between a Bitcoin Block and a GPU workunit called a block?

If there is a relation, was this intentional?


texts: How a block is defined (size, number of transactions)?

texts:
While exploring the Blockchain.info charts, I learned that:

The average size of blocks is increasing (max=1MB).
The number of transactions in one block is also increasing.

After reading some related articles, is it right to say that

One block is defined (solved) by mining. If I have a super powerful computer, I can mine so quickly that one block will only contain one transaction. (I'm trying to understand if there is a link between the number of transaction and the mining speed.)
The transactions in the same block are not linked between each other. So miners do solve one transaction, but one block.


texts: How to use deriveaddresses via a curl command

texts:
I am trying to use curl via SSH to utilize the deriveaddresses bitcoin-cli rpc command.

let descriptor = "wpkh(xpub6Dy2ikUu5mXbDdhw2vAP1C4eiQM8rTz1NiWQt2BzGi83iHC2gEgTSD54JveyuHF9VLAqNkCGnee1jdBL7nA3JNorbqjSSS8DEV6Hn3PuNBt/*)#mn5jvyc3"

    let command = "curl --data-binary '{\"jsonrpc\": \"1.0\", \"id\":\"curltest\", \"method\": \"deriveaddresses\", \"params\": [\"\(descriptor)\" 99] }' -H 'content-type: text/plain;' http://user:password@127.0.0.1:8332/"

    var error: NSError?

    let queue = DispatchQueue(label: "com.app.getInitialNodeConnection")
    queue.async {

        if let responseString = self.ssh.session?.channel.execute(command, error: &error) {

            guard let responseData = responseString.data(using: .utf8) else { return }

            do {

                let json = try JSONSerialization.jsonObject(with: responseData, options: [.allowFragments]) as Any

                print("json = \(json)")

            } catch {

            }

        }

    }`

I get the following error:

json = {
    error =     {
        code = "-32700";
        message = "Parse error";
    };
    id = "<null>";
    result = "<null>";
}

Is it not working because I need to escape special characters in the descriptor?


texts: Is it possible, with bitcoin-core or btcd, to manually set the scriptSig field in a coinbase transaction?

texts:
I am talking about when using regtest or simnet modes.

For context, it is so that I can create coinbase transactions with reproducible txids.


texts:
What's the best way to introduce Bitcoin to the family and friends?
Has anybody succesful experience in the topic?


texts: What happens when the verification of a manipulated transaction fail?

texts: If a malicious miner changes the amount in a given transaction, the hash value of the block changes. Thus, he has to find the required hash value again in that block. Let's say he successfully found the hash value. But what happens to the verification of the transaction the miner has changed? Suppose that he doesn’t have the private key of the sender, verification of this digital signature will fail at this point. Can the malicious miner still be able to add this block to a new chain or is there any mechanism to detect this failure and prevent him from making a new chain?


texts: How exactly does bitcoin code change happen in a decentralized system

texts:
I have long been under the assumption that bitcoin was just a "protocol" or a "contract“. Different nodes run their own implementation, on different hardwares. Some are efficient, some not, and they have to agree to the bitcoin protocol to function in this ecosystem.
But I found out there is actually a centralized bitcoin code base that's frequently updated! How do they even ensure that every nodes update to the newest code? And how do they ensure that the code compiles for every single hardware? Or, I guess most imporantly, were there any backward incompatible changes in the history that require every node to update?


texts: How would an atomic exchange of assets be implemented in a blockchain?

texts:
There are non-Bitcoin blockchains being created at the moment that are used to trade and transfer assets. It is my understanding that on such a block chain there are "tokens" representing assets such as a share in a company or some other security.

Assuming A wants to exchange with B some assets, how would they create a transaction so that the exchange happens atomically?

A non-atomic solution would be to have A transfer the assets he is selling to B first. Then, B transfers the assets he is paying with back.

Multisig transactions do not seem to solve this problem: One of the signers has to sign first (A). He cannot force B to then sign as well. B might abort the transaction or delay it. This is a trust issue and not atomic.

For a concrete example, A might want to trade a certain Namecoin domain name against another name that is owned by B. This is supposed to be trustless and atomic.


texts: How are gridcoin transactions validated?

texts:
Bitcoin uses it's calculations to validate transactions but apperently gridcoin doesn't take any transaction data into the calculation of BOINC projects.
On the wikipedia page of Gridcoin the following is stated:

  Gridcoin (sign: Ǥ, symbol: GRC) is an open source network protocol using blockchain

It says blockchain is used but how? How are transactions validated?


texts: I have a casascius coin -- how can I sell it?

texts:
I was given an actual casascius bitcoin minted in 2011 as a tip, and I'd like to know where I can exchange it for US dollars.

How would I extract the private key from this coin to gain access to the digital bitcoins if I were to sell them online?


texts:
I understand that a lot of people today stack Bitcoin instead of spending them and that makes sense because there is a limited number of bitcoins.

However, I think that for bitcoin to be a real currency that people use everyday there should not be a limited number of bitcoin so people could freely spend them without to care.

Why bitcoin was made this way with a limited number of bitcoin ?


texts:
I am using settxfee(0.00020) before sendtoaddress RPC call however after sending 0.042 in blockchain a fee of 0.000045 is showing.

How can I set the fee properly ?

Thanks


texts: If only six blocks are solved per hour, then how are more than six miners getting paid per hour?

texts: According to this page on average six blocks in the Bitcoin network are solved per hour, yet there are thousands of Bitcoin miners and presumably more than six of them are making money every hour. What am I missing?


texts: What is the threat model of a Bitcoin HSM / Hardware Wallet?

texts:
There are many devices available which purport to allow for the secure storage of Bitcoin in adversarial environments, such as compromised computers or potentially untrusted host devices such as phones.

How secure are these devices for storing Bitcoin, and what is the threat model that they protect against and are vulnerable to? How much do commonly stated practices about using these devices improve the safety of storing Bitcoin using them?


texts:
I'm confused about the inclusion of the hash of the previous transaction in a transaction. Is it mandatory? Should it be the hash of the last outbound transaction? What if an unexpected transaction messes up the linked list? I have written specific scenarios below for which I am unsure about the behaviour.

I have an account A for which its only transaction T1 was receiving 1 BTC from some other account. If I want to spend my 1 BTC in a transaction T2, do I need to include the hash of the transaction T1 in T2?
I have an account B which so far only received 1 BTC from a transaction T1 and I want to spend the 1 BTC in a transaction T2 referencing T1. But just before broadcasting T2, a transaction T3 also referencing T1 credits my account with 1 BTC. Will T2 be accepted despite T3 entering the blockchain before T2?
I have an account C to which someone will send 1 BTC tomorrow in a transaction T1. Is it possible to "pre-spend" the 1 BTC in a transaction T2 without knowing the hash of T1? By pre-spend I mean that as soon as my account gets credited with the 1 BTC from T1, transaction T2 can immediately also enter the blockchain.


texts: If I have a join shared wallet and my partner lost the backup, can we recover this if i can i see the BTC yet?

texts: I had a Join Shared Wallet. I can see my BTC; but my partner can´t because she lost the back up words. We aere trying to send this to an other wallet but it´s imposible if the other account doesn´t authorized it. What can I do for recovering these wallet?


texts: Which wallets are built deterministically? (Besides Bitcoin Core)

texts:
Bitcoin Core can be built deterministically, allowing anyone to compile the software themselves and compare it to the released version to see if they're identical.  Presumably, software forks of Bitcoin Core like Bitcoin Knots also provide this capability, and I recall that some people did this also for BIP148 UASF forks of Bitcoin Core.

What other software[1] wallets typically provided in pre-compiled form[2] are deterministically built?  Deterministic builds seem like a powerful and useful security feature, but as far as I know, almost no software wallets besides Bitcoin Core provide that feature.

Note: deterministic builds should not be confused with BIP32 Hierachical Deterministic (HD) wallets.

[1] Some hardware wallets, like Trezor, provide deterministic builds of their firmware, which is a nice feature.  However, that does nothing to prove the security of the hardware, which is hard to audit with the tools found even in a typical geek's home office.

[2] That is, not provided entirely using interpreted code.


texts: Transfer BTC from paper wallet without 3rd party (like blockchain.com etc)

texts: I have btc on my paper wallet and I want to transfer to some other address. How can I do this without sharing my private key to some other site like blockchain.com or electrum?


texts:
I'm from Bangladesh. I would like to buy bitcoins. So I went to Buybitcoin.com  and filled an order. Later I googled that site and read a lot about if being a scam site. So I'm a bit scared now. do not want to be scammed.

I've already tried ecurrencyzone.com but they do not take bank deposits from Bangladesh. this is terrible. Anyway can any of you fellow Indians guide me to proper genuine links where I can buy Bitcoins. My options are Western Union, Moneygram and best option is Bank deposit.


texts: How can I get the corresponding public key of a particular private key using bitcoin core console commands? , just as we can have private key of particular address using dumpprivkey and public key using validateaddress .


texts: I have a lot of confusion about bitcoin. What is the real worth of a bitcoin. For instance currency used to be backed by gold but now a days its fiat currency all around us.


texts: how i can make bitcoin address generator like mycelium gear using php script

texts:
this is the code i got,how i can generated new random address using 1 pubkey,everytime page refresh;i try to use timestamp but din't work.

<?php

// step 1

$publickey='0450863AD64A87AE8A2FE83C1AF1A8403CB53F53E486D8511DAD8A04887E5B23522CD470243453A299FA9E77237716103ABC11A1DF38855ED6F2EE187E9C582BA6';

$step1=hexStringToByteString($publickey);

echo "step1 ".$publickey."
";

// step 2

$step2=hash("sha256",$step1);
echo "step2 ".$step2."
";

// step 3

$step3=hash('ripemd160',hexStringToByteString($step2));
echo "step3 ".$step3."
";

// step 4

$step4="00".$step3;
echo "step4 ".$step4."
";

// step 5

$step5=hash("sha256",hexStringToByteString($step4));
echo "step5 ".$step5."
";

// step 6

$step6=hash("sha256",hexStringToByteString($step5));
echo "step6 ".$step6."
";

// step 7

$checksum=substr($step6,0,8);
echo "step7 ".$checksum."
";

// step 8

$step8=$step4.$checksum;
echo "step8 ".$step8."
";

// step 9
// base conversion is from hex to base58 via decimal.
// Leading hex zero converts to 1 in base58 but it is dropped
// in the intermediate decimal stage.  Simply added back manually.

$step9="1".bc_base58_encode(bc_hexdec($step8));
echo "step9 ".$step9."

";

function hexStringToByteString($hexString){
    $len=strlen($hexString);

    $byteString="";
    for ($i=0;$i<$len;$i=$i+2){
        $charnum=hexdec(substr($hexString,$i,2));
        $byteString.=chr($charnum);
    }

return $byteString;
}

// BCmath version for huge numbers
function bc_arb_encode($num, $basestr) {
    if( ! function_exists('bcadd') ) {
        Throw new Exception('You need the BCmath extension.');
    }

    $base = strlen($basestr);
    $rep = '';

    while( true ){
        if( strlen($num) < 2 ) {
            if( intval($num) <= 0 ) {
                break;
            }
        }
        $rem = bcmod($num, $base);
        $rep = $basestr[intval($rem)] . $rep;
        $num = bcdiv(bcsub($num, $rem), $base);
    }
    return $rep;
}

function bc_arb_decode($num, $basestr) {
    if( ! function_exists('bcadd') ) {
        Throw new Exception('You need the BCmath extension.');
    }

    $base = strlen($basestr);
    $dec = '0';

    $num_arr = str_split((string)$num);
    $cnt = strlen($num);
    for($i=0; $i < $cnt; $i++) {
        $pos = strpos($basestr, $num_arr[$i]);
        if( $pos === false ) {
            Throw new Exception(sprintf('Unknown character %s at offset %d', $num_arr[$i], $i));
        }
        $dec = bcadd(bcmul($dec, $base), $pos);
    }
    return $dec;
}

// base 58 alias
function bc_base58_encode($num) {
    return bc_arb_encode($num, '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz');
}
function bc_base58_decode($num) {
    return bc_arb_decode($num, '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz');
}

//hexdec with BCmath
function bc_hexdec($num) {
    return bc_arb_decode(strtolower($num), '0123456789abcdef');
}
function bc_dechex($num) {
    return bc_arb_encode($num, '0123456789abcdef');
}
?>


texts:
Lightning Network uses Revocable Sequence Maturing Contracts.
The LN Paper specifies that:

If one wishes to permit revocable transactions [...] the output
transaction construction would remain a 2-of-2 multisig:
2 Alice1 Bob1 2 OP CHECKMULTISIG

However, the current implementation uses elliptic curve point multiplication (not multisig).
I have found this information in BOLT03 - to_local, but also here.
The benefits of the current approach are:

smaller size of the Output Script
only one signature required to unlock (vs 2 in the original spec)

Are there any other considerations besides these two for using elliptic curve point multiplication instead of multisig?


texts: I've inherited BTC, how do I recover and sell it?

texts:
Update>>> I have the 12 word phrase and the 34 letter and number address for wallet...
Mom passed away the day after Thanksgiving. I have all her paperwork and mine as I was her only child. I have a string of numbers and letters and a 12 word collection related to her bitcoin however I am not at all familiar with bitcoin and am not very versed in technology. How should I proceed? Thank You.


texts:
The following link contains details on how to reverse the ECDSA signature if given two identical "R" values.

http://www.nilsschneider.net/2013/01/28/recovering-bitcoin-private-keys.html

I have read over this and there's one part I don't understand; how he got the "z" values.

Does a copy and paste of
"OP_DUP OP_HASH160 70792fb74a5df745bac07df6fe020f871cbb293b OP_EQUALVERIFY OP_CHECKSIG" (minus the quotations) into a ripemod-160 hashing function produce that result?

Did he have to essentially copy and paste some other string?  Did he just ripemod or sha 256d?  Did he have to do it more than once?

I've read up on these things but I just cannot decipher their programming description of how to do it.  The non-programming descriptions don't show "hey this 'xyzx' is what I'm referring to when I say 'message to be signed'" or whatever.  Many things on that page and on the

https://blockchain.info/tx/9ec4bc49e828d924af1d1029cacf709431abbde46d59554b62bc270e3b29c4b1

Seem as though they could adequately be described as the "message to be signed" besides the fact I don't know what type of hash is being applied to even compare my calculations with the ones shown on the first link.


texts: Are there any opensource PHP cryptocurrency exchange/marketplace

texts:
As the title suggest, are there any opensource PHP cryptocurrency exchange/marketplace.

Most of the ones I found does not seem to work or are abandoned.


texts: How to securely update and verify C-Lightning release?

texts:
Recently, a new version (v0.7.3) of C-Lightning was released. The GitHub page has detailed instructions on how to build the software from source, but does not provide much details as to how to update the software from the pre-built binaries from the release page.

I'm looking for instructions as to how to update the C-lightning software from the pre-built binaries for different OS (Windows, Linux, Mac etc.)

How do I verify the release signatures of the C-Lightning pre-built binaries?


texts: Formula for calculating bitcoin transaction size doesn't always work out but why

texts:
Please refer to this question:

Calculator for estimated TX-Fees

I have a question for clarity, in response to James' answer as in his example of 2 inputs/1 output, I recently calculated using the formula provided in that question (and found all over the web) and confirming my inputs are both compressed:

size := X * 148 + Y * 34 + 10 +- X

I'm using a standard Electrum wallet with 2FA.  I had 2 inputs each it's own address and a single output and wanted to spend them to a single address w/ no change address. 2-in/1-out

I calculated: (2 x 148) + (1 x 34) + 10 +- 2 = 338-342 bytes and James came up with 404 bytes (he used uncompressed inputs @ 180 bytes and the formula works out), yet the real transaction would up being 638 bytes (stuck in the pool now) which makes using formulas like the one above a little less trustworthy.

What am I missing? Why when using the formula above, some transactions are spot on and others are way off with no way for me to make sense of it, math doesn't lie so I must be using the formula wrong and I just can't see the forest through through the trees?

Short Answer (derived from the help of all 3 fine gents below): I am using a 2FA wallet and that inherently is a multi-signature wallet of which the formula (in my case, 2 signers) changes the formula to:

size := X * 295 + Y * 34 + 10 +- X


texts:
I understand that Coinbase creates many btc addresses per wallet. I am not sure though that if you have an overall zero balance (or $0.01 overall) all your associated btc addresses should also have a zero balance.

So, here is the actual question: I see that one of my btc addresses associated to one of my coinbase wallets (let's call the address ABC123) still has a bitcoin non zero balance. It's not a rounding issue as the balance is too large for this. Overall my coinbase balance is almost zero. Does this make sense?

When I go to https://bitref.com and check ABC123 I can see the balance.


texts: How do you resend a transaction without running a full node?

texts:
The answers to the canonical "my transaction has been pending for too long" question require hundreds of GB of hard drive and bandwidth. I cannot meet such requirements to run a full node.

How can a 15 sat/B, 389 B Segwit unconfirmed transaction to Coinbase be replaced (transaction inputs double-spent?) with a higher transaction fee without downloading the entire blockchain on a full node?


texts: Is it possible to transmit a tx over the network that does not go into the blockchain?

texts:
Can I somehow create a transaction that is broadcasted over the bitcoin network but will not go into a block?

Might be handy for SatoshiDice like confirmations.

edit:
What I have in mind is transporting information over the bitcoin network without bloating the blockchain.


texts:
I have got my new Trezor but I don't know how to connect my existing myetherwallet to trezor ether address ?

Is there any way I can directly import and connect to trezor ?
Or I have to create a new myetherwallet with trezor and transfer ethereum and other erc20 coins from old myetherwallet to new ether trezor address ?


texts:
How do mining contracts work?
I see mining contracts but how does it work?.
What happens when I buy one?  .
I've seen multiple mining contracts I don't know whether the prices are worth it because I have no idea what they are.  Anyone care to explain ?


texts: Should I buy my Bitcoins now before a 2016 fork happens with Classic vs Core?

texts:
Having read about the the fight of Core vs Classic and the potential of a fork happening. I have a few questions concerning what would happen when a fork happens. I feel its inevitable a fork will occur. Currently our coins reside on just one chain the Bitcoin core chain at the moment. If a fork were to happen and Classic takes over, my coins prior to the fork will reside on both chains. But if a fork happens now I must decide on which chain to buy my coins on. Is this correct?

It's safe to assume that when the fork happens there will still be a certain amount of nodes clinging to the less popular chain creating an extra Bitcoin blockchain. At first the coins on this less popular network will plumment in price, but it will stabilize at a much lower price compared to the main chain. Now the users pre-fork will have 2 separate accounts containing the same amount of coins. Is this correct?

Now my question is, would it be wise to buy your coins before the fork? Then sell the less popular forked coins when it happens? Or is there another scenario that might play out that I haven't factored in yet?


texts: Multisig where one of the keys specifically is required?

texts:
Is it possible to make a multisig wallet that requires one of the keys specifically and any of the other ones in order to sign a transaction?

For example, let's say I have a 2-of-3 multisig that has signators A, B, and C. Can I make a multisig that requires that every transaction be signed by A specifically and then one of either of the other keys?


texts: Please how will the receiver of the bitcoin know that I send the bitcoin into his wallet. And how do i send the bitcoin into another person's wallet


texts: Can the sender of a MtGox code see which account the code is redeemed to?

texts: In other words, if I receive a MtGox code and redeem it to my account, can the person who gave me the bitcoins, via the code, see that my account was the account that redeemed it?


texts: Why do mined blocks tend to vary so much in size. If the miner's objective is to maximize their revenue from transaction fees they should add transactions starting with the one with the largest fee, working down to the one with the lowest until the pool of waiting transactions is empty.


texts: ELI5: What's the difference between a child-key and a hardened child-key in BIP32

texts:
I've read BIP32, and I do understand it more or less.

Could someone please explain to me like I'm 5 years old what the difference between a child-key and a hardened child-key is?

I'm trying to add HD wallet generation to a service I'm building. I need to be completely informed about this before I dabble in it. Fret not, I'll be using Bitcore, so I won't be dabbling with the crypto directly.


texts: What percentage of merchant Bitcoin receipts are immediately converted into fiat?

texts:
Does anyone have access to this data from Bitpay or Coinbase perhaps?

If so please break down the data by country and industry if available and how these statistics have changed over time.


texts:
So I have downloaded Bitcoin-QT v0.8.6-beta.
It has downloaded everything and now this folder:

C:\Users\user\AppData\Roaming\Bitcoin\blocks

is 17GB

Anyway to prune/delete something?


texts:
I am building a native Ripple Android wallet.

I understand that the BlobVault is currently centralized so what are the Ripple Labs server addresses that is safe to connect to those API servers - BlobVault and authd?

Maybe my understanding is limited and I am asking the wrong question, but:

What is the address of the servers that run the BlobVault and authd API?

Thanks!


texts:
When are Bitcoin transaction outputs generated more than two?

In my understanding, if my wallet has only UTXOs that have more values than i wanted to spend(send), then two outputs are generated which one is for sending my BTC to someone and another is for change to my wallet back. But I saw several transactions in bitcoin explorer that has more than 3 outputs. What are they?


texts: Using scantxouset method on bitcoind JSON RPC

texts:
BitcoinRPC class from here (ruby): https://en.bitcoin.it/wiki/API_reference_(JSON-RPC)

btc = BitcoinRPC.new("http://rpcuser:rpcpassword@127.0.0.1:18332")

btc.getaddress    => "2NCixvAERq3eDt31jM7eYATGiHdTEcizQkj"     THIS WORKS

arguments =  { action: 'start', scanobjects: ["addr(mfskMRWntcPYdDgTJRJdwzdKiiHJikfvH4)"] }.to_json

btc.scantxoutset(arguments)  => BitcoinRPC::JSONRPCError: {"code"=>-8, "message"=>"Invalid command"}   Doesn't work...


texts: Is there anything comparable to a "board of directors" for Bitcoin or is the software on complete cruise-control?


texts: Why does Bitcoin use two hash functions (SHA-256 and RIPEMD-160) to create an address?

texts: Why do we use 2 hash functions (both SHA and RIPEMD) to create an address? Why not just use one hash function?


texts: What is meant by "we are approaching a step change in bitcoin mining"

texts:
On a comment on this answer: https://bitcoin.stackexchange.com/a/9494/4173

The following was said: "However, what you need to consider is that we're approaching a step change in bitcoin mining with the creation of ASIC-based minders. These will increase the difficulty 10-fold pretty much immediately, and go to 100-fold if they are successful. "

Can anyone explain what this means?  What is a minder? Why is the difficulty about to increase 10 / 100 fold?


texts: How to calculate Tapscript sigops budget?

texts:
Sigops limits have been changed to budget in Tapscript. BIP341 defines the budget calculation method as follows.

The budget equals 50 + the total serialized size in bytes of the transaction input's witness (including the CompactSize prefix). Executing a signature opcode (OP_CHECKSIG, OP_CHECKSIGVERIFY, or OP_CHECKSIGADD) with a non-empty signature decrements the budget by 50.

https://github.com/bitcoin/bips/blob/master/bip-0342.mediawiki#Resource_limits
This CompactSize prefix include the number of witness elements at the beginning?
For example, if I have the following 5 sizes of witness data,

compact size
witness size

1
65

1
64

1
91

3
257

3
563

The total size including the above Compact Size is 1049. In addition to this, do I need to add the number of bytes(1) of CompactSize for the number of elements(5)?
That's because the above data output by Bitcoin Core feature_taproot.py is 1050. The final budget will be 1100, which is 50 added to this.


texts: What is the dust limit on Bitcoin Cash transactions?

texts: I understand from another question here on Stack Exchange that the dust limit for Bitcoin transactions is 546 satoshi, meaning that no transaction output may be on an amount less than that. What is the equivalent dust limit for Bitcoin Cash transactions?


texts: When does the "reject" string have an empty reject reason upon submitting a new block?

texts:
I submitted a new block using the rpc command submit. And I just got a "reject" string without a reject reason.

I checked the bitcoind source code, and found that it usually sends a reject reason; bitcoind would only omit a reason if the strRejectReason is empty. Why and when would the strRejectReason be empty?

static Value BIP22ValidationResult(const CValidationState& state)
{
    if (state.IsValid())
        return Value::null;

    std::string strRejectReason = state.GetRejectReason();
    if (state.IsError())
        throw JSONRPCError(RPC_VERIFY_ERROR, strRejectReason);
    if (state.IsInvalid())
    {
        if (strRejectReason.empty())
            return "rejected"; // The value that gets returned
        return strRejectReason;
    }
    // Should be impossible
    return "valid?";
}

Source.


texts: How does the Bitcoin block propagation process recover when false positive happens?

texts: I have read articles about how Invertible Bloom Filters (IBLT) work and I have some basic knowledge how Bitcoin works for block propagation using IBLT. But since IBLT would introduce false positive, participants in the network would have a chance in unsuccessful in receiving all differences between two IBLTs. So I am wondering how Bitcoin solve this problem to recover all blocks?


texts: Will an attacker's forked branch of block chain be used in bitcoin confirmation?

texts:
From what I understand, transactions are agglomerated into a block, proof of work is done by computing a hash value for the block, then added to the block chain. When a block is added to the block chain, then the transaction included in the block is considered to be confirmed.

How is the full node from which the block chain is queried decided? Or how many full node's block chain is a transaction checked against?

Suppose an attacker has a forked chain, and let us assume nothing about other full nodes' rejection or confirmation about this fork, can my transaction be checked against this forked chain of the attacker and not against other valid block chains maintained by honest full nodes?

Suppose I succeeded in 6 confirmations, but all these blocks are an attacker's fork. Is this a problem?


texts: Regardless of how bad it is for the network, wouldn't mining an empty block be signifigantly less work?

texts:
A block contains the previous block's hash, a nonce, and series of transactions. That information needs to be hashed until the block's hash meets the number of leading 0 requirement.
My question is, since we have to hash all the transaction data as well, wouldn't it be significantly easier in terms of processing power to mine an empty block (just the prev hash and nonce) or a block with very few transactions?


texts: C++ Proofofworklimit to bitcoinj util.DecodeCompactBits

texts:
What is equivalent bitcoinj  util.DecodeCompactBits for below c++.

Cbignum(~uint256(0) >>32)

Cbignum(~uint256(0) >>20)

Cbignum(~uint256(0) >>23)

Cbignum(~uint256(0) >>22)


texts: What values are legal for the transaction's version field?

texts:
In the transaction's version field, what values are legal?

What values have actually been seen in the blockchain?


texts: How to open new wallet into Bitcoin Core and switch between?

texts:
I have my old wallet which private key is compromised. So my reasonable way is to open new wallet and move all bitcoins from compromised wallet to new wallet.

I use Bitcoin Core. I do not trust any online wallets because private key stored into remote store.
So how can i open new wallet and move all bitcoin to it using Bitcoin Core only?


texts:
On my vps I decided to start mining litecoin because I wasn't really using the server for anything. I thought, why not?

I ran the cpuminer script with the correct command line arguments and it connects to the mining proxy fine. It mines like normal for a few minutes.

It works pretty well and then the script just says Killed and gives me the command line. I can run the same command again and mine litecoin for a few minutes and the same thing happens. I think this is the work of my vps hoster (vpscheap.com if it helps). What could be causing this and is there any way to get the script to automatically restart when it is killed? Any help is appreciated.

p.s the server is ubuntu 13.04-x86-64


texts: what file/method is block reward processed?

texts:
I have managed to build an altcoin (from litecoin source) but my coin requires that I make changes to the way rewards are made. I have been looking at the source code to try to find where block reward is handled and what method does all the work. I did find this (In what line of what file does the block reward depend on?) however this looks to be old as i don't see a main.cpp file in the litecoin source.

does anyone know the modern files/methods that handle this. I already managed to follow the steps for creating my genesis block and everything looks to be working. I'm now in the phase of making changes. I would like to find the method that handles creating a block with a block reward. I will be changing how the block reward is done.

while I see chainparams.cpp has an ability to change the reward amount. I'm looking for a way to build a new type of reward system so i will need to look at how a coin is made from nothing. My coin will not be minting coins on block creation so i need to change how that method works.


texts: How to perform atomic swap Bitcoin-Litecoin

texts:
I am running Bitcoin and Litecoin nodes fully synced on testnet.Can I perform atomic swapping by using this networks?

I heard it can be done through HTLC(Hash Time Locked Contracts). How can I do exactly by HTLC and trying to go deeper in to HTLC?

Thanks.


texts:
Anyone can give step-by-step explanation about the code below (if possible, with a c/c++ equivalent)?

import hashlib, struct

ver = 2
prev_block = "000000000000000117c80378b8da0e33559b5997f2ad55e2f7d18ec1975b9717"
mrkl_root = "871714dcbae6c8193a2bb9b2a69fe1c0440399f38d94b3a0f1b447275a29978a"
time_ = 0x53058b35 # 2014-02-20 04:57:25
bits = 0x19015f53

# https://en.bitcoin.it/wiki/Difficulty
exp = bits >> 24
mant = bits & 0xffffff
target_hexstr = '%064x' % (mant * (1<<(8*(exp - 3))))
target_str = target_hexstr.decode('hex')

nonce = 0
while nonce < 0x100000000:
    header = ( struct.pack("<L", ver) + prev_block.decode('hex')[::-1] +
          mrkl_root.decode('hex')[::-1] + struct.pack("<LLL", time_, bits, nonce))
    hash = hashlib.sha256(hashlib.sha256(header).digest()).digest()
    print nonce, hash[::-1].encode('hex')
    if hash[::-1] < target_str:
        print 'success'
        break
    nonce += 1

I am trying create my own implementation; I already read the block data with json-rpc and stored in this struct:

struct block {
  unsigned char* hash;
  int confirmations;
  long strippedsize;
  long size;
  long weight;
  long height;
  long version;
  unsigned char* versionHex;
  unsigned char* merkleroot;
  long blocktime;
  long mediantime;
  long nonce;
  unsigned char* bits;
  double difficulty;
  unsigned char* chainwork;
  unsigned char* previousblockhash;
};

Now I want extract the data from this struct and use to execute the same calculations in this code, but I need to understand what the code does with more details.


texts:
Vanity address generation is currently strightforward for "old" Bitcoin addresses (starting with 1) with multiple software options available (oclvanitygen e.t.c).

Is there any options to generate SegWit Vanity address (starting with 3)? Or it is already possible to configure existing software for Segwit addresses?


texts:
I tried:

lightning-cli invoice 100 invoice20190126 payme

and nothing happens. How to debug?


texts: Who can see my IP address while using Electrum

texts:
Who exactly is my IP exposed to when sending transactions in Electrum.  I'm assuming the server operators can see it every time I connect (to query the servers about my balances).

When I make a transaction, is my IP recorded and logged into blockchain.info (or is it the IP of the server who relays the transaction).

If so, does this make Electrum unsafe to use with larger balances? i.e tying large amounts to a single IP?


texts: is there a tool to produce addresses given a master public key?

texts: I have master public key of my wallet and I want to generate addresses but without using my current wallet. Is there a tool that does that?


texts: What is Bitcoin locking and unlocking script?

texts:
The locking script on an UTXO and the unlocking script are written in bitcoin scripting language. When a transaction is validated, the unlocking script in each input is executed alongside the corresponding locking script to see if it satisfies the spending condition.
Can someone explain the nitty gritty of Bitcoin script with locking and unlocking script?


texts: Service or application to auto sweep specified BTC private keys?

texts: Is there a service or an application that will auto sweep a bitcoin private key to your own wallet? I want to monitor a few private keys and sweep them once they receive funds in it.


texts: What is the mathematics behind the maximum number of 21 million bitcoins that can be generated?

texts: How is this number 21 million bitcoins arrived at? What is the mathematics behind this number? Or is this number a constant that can be changed in the source code?


texts: Is there a BTC Address generator that will check first blockchain if unused?

texts:
I'm looking for a working implementation of a Bitcoin address generator that would accept string or integer then it will check the blockchain if the address is unused before it will print the keypairs.

Any repositories with similar function is highly appreciated.
Thank you.