can cryptocurrencies be energy efficient? Is there an intrinsic reason why cryptocurrencies currently take a lot of energy to keep working? Is there a way to make a cryptocurrency still widely used but make it energy efficient?

As the answer for this question, we have the Proof of Stake approach, firstly implemented by Peercoin (PPC). I think other coins as Ethereum have as well a proof of stake mining/minting approach

links: https://peercoin.net/minting and https://github.com/peercoin/peercoin/wiki/FAQ

It would seem so.
Ethereum has partly switched from Proof of Work to Proof of Stake: https://en.wikipedia.org/wiki/Proof_of_stake
... and we may well look back on energy expenditure of Proof of Work as almost all total waste:
https://stuart-reynolds.medium.com/is-bitcoins-energy-consumption-a-problem-for-the-world-ff213cc2136a


Can we decouple tx fee from the txs themselves? We know that, in general, miners prefer putting txs with higher fees into blocks. In particular, this is bad for users who do microtransactions as it doesn't make much sense to put a lot of fee if you're only sending a small amount. I've been thinking whether it is possible to overcome this.

Basically, if we somehow find a way to decouple fees from the txs themselves then every tx will look equal to the miners. When this is the case, there's no incentive to prefer one tx over another. I believe this would make the Bitcoin more "fair" to the users.

However, I can't tell whether it is possible to come up with such a protocol while maintaining the properties of the Bitcoin. What I have in my mind is basically as follows:

Users first send some "participation tax" to an adress/adresses
which is collectively maintaned by the miners.
Miners in turn collectively sign a token and send back the token to users.
Users then include this token in their txs to prove their validity. Txs without tokens can be either be discarded or might have less priority.
The total tax sum in the pool is distributed to miners according their fraction of hash power.
The process repeats over time periods.

The key point in here is, every tx with a valid token would look the same for miners. So, there's no reason to choose one over another.
Of course, as it is, it probably has many flaws. For example, a user can pay participation fee and his txs might still not make it to the block. In this case, he basically pays the participation fee for nothing. Maybe we can overcome this with a "decentralized escrow" mechanism (not sure if this even exists) but anyway, this needs to be worked on.

What do you think ? Might such a system help the Bitcoin in a way ?

Bitcoin mining is business. It incurs significant hardware and energy costs. So it's absolutely understandable and legitimate that the commercial miners choose those transactions that give the biggest overall fee. And a 10-Satoshi transaction occupies the same space in the block as a 100-Bitcoin one. It's a bit like in real life: some countries in the Euro region don't circulate 1- or 2-cent coins because their production costs more than their nominal value. And everybody there accepts that a change of 1 or 2 cents is lost.

Your suggestion is implementable within the current bitcoin consensus if you can convince a significant portion of the miners to follow that scheme. Every miner is free to implement his own priority scheme for transactions, not necessarily based only on transaction-internal data.

But I doubt that you'll be able to convince enough miners and users to switch to that scheme. Miners will lose fees, and users will have to pay in advance to get a token that's only accepted by a (small?) portion of the miners.

If you want to help with low-volume transactions, start your own miner with a priority scheme that prefers low-volume transactions. You'll lose money running your mining hardware, but some users will benefit.

Basically, if we somehow find a way to decouple fees from the txs themselves

it is not possible without hardforking bitcoin
nobody is interested in it and nobody will implement it
you can create your own altcoin with this consensus rule included

  Might such a system help the Bitcoin in a way ?

Why do you think that bitcoin needs your help?


Why was the target block time chosen to be 10 minutes? According to the wiki, 10 minutes was chosen as a 'tradeoff'.

Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the amount of work wasted due to chain splits.

However in the original Satoshi paper, 10 minutes is merely assumed for the purposes of calculating disk space requirements.

A block header with no transactions would be about 80 bytes. If we suppose blocks are
generated every 10 minutes, 80 bytes * 6 * 24 * 365 = 4.2MB per year.

Is there a discussion elsewhere that explains how the 10 minute block time was arrived at?

10 minute blocks is simply a compromise.

Shorter block time:

PRO - Faster 1 confirmation time (to protect from 0-confirm double spend)
PRO - Less payout variance for miners (less reliance on large pools)
CON - Requires increased bandwidth (inter node communication)
CON - More forks, longer forks, and longer re-org time
CON - A greater portion of the raw hashpower is wasted, resulting in lower effective security.

With a longer block interval target of longer than 10 minutes, the pros and cons would be reversed.

The major benefit of a shorter block time is the reduced 1 confirm time.  While a quicker block's 1 confirm transaction has less strength than a longer block's 1 confirm transaction it is still better than any block's 0 confirm transaction.

The speed of 1st confirm may seem to be a huge benefit but in reality for most low value and time sensitive transactions such as the buying a cup of coffee, paying for a taxi, or using a vending machine, the risk of double spends is very low. Keep in mind that accepting credit cards is not without risk however merchants have long accepted they will face some losses however if those losses are minimal then it can just be seen as a cost of doing business.  So many merchants could simply accept 0-confirm transactions without exposing themselves to more risk than they do from credit card fraud.

The other factor that diminishes the real world potential of shorter target block intervals is that for many merchants, even  "faster" confirmation times still isn't fast enough. For a Point of Sale transaction, an average confirmation time of 2 minutes is still significantly longer than what most merchants would consider to be workable. The average credit card transaction takes about 20 seconds (including delays by customer).  The entire industry has spent significant resources to shave even a few seconds off.  Changes like enabling customer to swipe card, swiping before all items have been rung up, and not requiring signatures on low value are all about shaving a couple seconds off an already quick process and the cost of those changes is considered acceptable in order to slightly improve the efficiency of a checkout.

The other factor is that reducing the target interval only reduces the average confirmation time but half of them will be longer and the tail can be very long. Due to the random nature of blocks solutions about 15% of blocks will take longer than 2x the target, 3% longer than 3x the target and >7.5 minutes and about 0.5% will take longer than 4x the target.  That uncertainty makes it difficult for a time sensitive business to as a matter of policy wait for confirmations.  Having most transactions confirm in 30 seconds but some take minutes is going to lead to customer frustration at the point of sale.

If the BTC economy grows large enough we could see expanded use of "green addresses" to fill the need for instant acceptance without confirmations.  Such services could be provided by major corporations, and backed by insurance against fraud (for a small per transaction fee).  This would be a more viable 0-confirm solution than a simple reduction of the block interval.

That being said the 10 minute target was probably overly conservative and there are some advantages to a shorter block time.

AFAICS, the only possible benefit to the longer block time is the reduction of bandwidth overhead due to less probability of block chain splits.

I even doubt that tradeoff, because if the transaction data is the bulk then there is the counter-balancing effect that shorter block times mean less data to transmit.

I am highly skeptical that there must be more work wasted with shorter block time, if the difficulty is calibrated w.r.t. the time to arrive at a consensus. Mathematically the miners earn a percentage of the newly created blocks proportioned roughly by their percentage of the system hash power, regardless the relative split in proportion of their luck between work difficulty and (the random) orphaned chains.

Unless there is a proof, I doubt the claim that shorter block times create longer times to arrive at consensus (i.e. re-org splits), because for example if there are 4 times more splits with 1/4 the block time, there are roughly 7 more iterations to arrive at consensus within the same duration.

G̶i̶v̶e̶n̶ ̶t̶h̶a̶t̶ ̶i̶r̶r̶e̶v̶e̶r̶s̶i̶b̶i̶l̶i̶t̶y̶ ̶i̶s̶ ̶a̶ ̶f̶u̶n̶c̶t̶i̶o̶n̶ ̶o̶f̶ ̶n̶u̶m̶b̶e̶r̶ ̶o̶f̶ ̶b̶l̶o̶c̶k̶s̶&̶m̶d̶a̶s̶h̶;̶ ̶n̶o̶t̶ ̶o̶f̶ ̶t̶i̶m̶e̶— ̶a̶n̶d̶ ̶t̶h̶e̶ ̶d̶i̶s̶a̶d̶v̶a̶n̶t̶a̶g̶e̶ ̶o̶f̶ ̶d̶e̶l̶a̶y̶s̶ ̶i̶n̶ ̶t̶r̶a̶n̶s̶a̶c̶t̶i̶o̶n̶s̶,̶ ̶i̶t̶ ̶s̶e̶e̶m̶s̶ ̶a̶ ̶s̶h̶o̶r̶t̶e̶r̶ ̶b̶l̶o̶c̶k̶ ̶t̶i̶m̶e̶ ̶i̶s̶ ̶c̶o̶m̶p̶e̶l̶l̶i̶n̶g̶.̶

I would appreciate if downvoters would at least try to defend their logic with a comment below my answer. That gives me an opportunity to debate them and show them why I think they are wrong (or to admit my mistake). The point is to make sure we collectively have the correct logic.


What is the supply for Bitcoin Cash (BCH), how is supply being regulated? We know that for BTC there is a max supply of 21 million.
50% reduction of 50 BTC per block for every 210000 block.

However, what is the mining reward per block, how is the supply being regulated? Can't seem to find any materail on it?

Bitcoin Cash has the same hard limit as Bitcoin, almost 21 million. In terms of supply, it is identical to Bitcoin, with the same halving of supply, at the same block heights.

However, there is a difference in the difficulty adjustment algorithm. Difficulty is the variable that ensures that there is one block mined every 10 minutes. It increases as the number of miners/hashpower in the network increases. In Bitcoin, the difficulty is adjusted every 2016 blocks, based on how long it took for those 2016 blocks to get mined. So every 2 weeks (approximately) the difficulty is adjusted based on how much hashpower was added to the network in that time.

Initially, Bitcoin cash had the same difficulty adjustment algorithm with one addition, which was called Emergency Difficulty Adjustement (EDA). If no blocks had been found for 12 hours, then the difficulty would reduce by 20%. This was put in place to prevent the chain from stagnating  and dying due to lack of hashpower as it was unknown as to how much support BCH would receive from miners.

This algorithm, however, was susceptible to being gamed by the miners. Miners would intentionally abandon mining BCH for a period of time. This would trigger EDA multiple times, and then when the difficulty was low enough to be profitable, they would start mining BCH, and mine 2016 blocks in 3-4 days (instead of 2 weeks). After 2016 low-difficulty blocks are mined, the difficulty would be readjusted to a sufficiently high amount, and the miners would abandon the BCH chain again.

If you compare the supply of BTC and BCH, in the 4 months since the fork, there is a difference in approximately 120,000 coins. This was problematic as BCH blocks were no longer predictable. The block times varied from 12+ hours to less than a minute.

On November 13th, Bitcoin Cash underwent a hard fork to change the difficulty adjustment algorithm. Now the difficulty is readjusted every block based on the previous 144 blocks, to try and keep block times as close to 10 minutes as possible.

Bitcoin cash is the same as bitcoin except it has SegWit2x implemented and it has bigger blocks (2MB I think). Bitcoin cash is hard fork of Bitcoin.

The benefits of bigger blocks are more transactions per block, the current Bitcoin block size is 1MB, which means Bitcoin Cash can process 2x more transactions.

The other difference - SegWit essentially moves part of block data into separate block and therefore can hold even more transactions. Transactions are faster and the fees are lower because there is less waiting to be processed transactions.

But with bigger blocks it is more expensive to support full node. Full node keeps all transactions locally.

With 1MB block and ~144 blocks per day mined, you will need 144MB per day, 1GB per week and 31GB for every month.

With 2MB blocks you'll need 144MB*2 per day, 2GB per week and ~62GB for every month. Who can afford this? Only big players and this means only one thing - centralization, we already have centralized banks and we don't want that, we want the opposite.

This calculations are based on the assumption that every block is filled to the max, with the current Bitcoin Cash blocks this is not the case because not so much transactions are going on right now and the blocks are ~100KB.


How to import bitcoins from one wallet to another wallet? I have purchased some fractional bitcoins from a website zebpay.com in india. I want to transfer those bitcoins to a wallet name jaxx so that i can buy ethereuem and other cryptocurrencies from jaxx wallet.

I can send bitcoin from zebpay to jaxx by pasting jaxx's bitcoin address in zebpay, but i have to pay transaction commission fee to zebpay for that. Is there any other way that i can just open my bitcoin in jaxx without giving any type of transaction fees?

Well you want to make a transaction from one wallet to another, and for someone to bother mine that transaction they should get paid that small fee.


How probable is a sybil attack? I'd like to know what's the probability of a sybil attack and if there are mechanisms built in to prevent this kind of attack?

One cool thing about Bitcoin is that coins are inherently scarse and this is by itself a huge protection from sybil attacks. In other P2P systems, sybil attacks are much harder to prevent because there's no such concept of scarcity. In Bitcoin, a sybil attack would be achieved if one has lot of coins, by sending tons of transactions, and therefore spending such coins.

There are other types of sybil attacks such as overloading nodes connections, and the recent one of filling up the memory pool of specific nodes with really tiny transactions. A way to prevent these would be for example to increase the fees.


What hash rate can a Raspberry Pi achieve? Can the GPU be used? A Raspberry Pi is a credit card sized $25 (or $45, for the deluxe option) computer, designed for educational use. Has anyone tried running mining software on it? If so, what's the hashrate like? (apparently the CPU is approximately equivalent to a P2 300MHz - I know the hashrate will be very low!)
Also, can the GPU be used to mine? What's the hashrate for that, if it's been done.
From the FAQ on the above linked site: "The GPU provides Open GL ES 2.0, hardware-accelerated OpenVG, and 1080p30 H.264 high-profile decode.
The GPU is capable of 1Gpixel/s, 1.5Gtexel/s or 24 GFLOPs of general purpose compute and features a bunch of texture filtering and DMA infrastructure.
That is, graphics capabilities are roughly equivalent to Xbox 1 level of performance. Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics."
Note: The price of $25 or $45 excludes a way of powering it (via MicroUSB), a keyboard, a mouse and likely a USB hub. I think you need to provide an SD card too.

There is a nice wiki page here: https://en.bitcoin.it/wiki/Mining_hardware_comparison

The raspberry pi is listed by its processor in the arm section: ARM1176JZ(F)-S. It gets 0.2 Mhash/s when clocked at 800 MHz.

Do you even know what FLOPS are, first off?

FLOPS stands for FLoating-point OPerations per Second. Hashes are calculated via signed integers in the form of hexadecimal numbers, those numbers are then run through a series of logical operations (You know; AND, OR, NOR, XOR, NAND).

FLOPS means absolutely jack when it comes to your processing speed of your Hash Bashing rig (your crypto-currency mining computer).

ATI cards are known for their single-precision floating point performance over Nvidia, that much is true.

ATI also has better signed and unsigned integer performance than Nvidia does too.

ATI has slightly better logical operations per second than Nvidia does.

Now, floating point is screaming fast on the ATIs as compared to the Nvidia but it's too bad it's not actually being used for SHA256D and Scrypt.

Integers both signed and unsigned actually take less time on the CPU or GP-GPU to calculate and thus much faster.

The logical operations are the slowest and since you use a combination of both logical and unsigned integer you get a composite average of the performance between the two and of course the implementation of the mining application.

If it's done correctly, you should get around 85 to 90% maximum of what your card or embedded system claims it's capable of doing. Simply put, you will never achieve 100% because you have an operating system that is using the card and of course interfacing to the rest of the system.

While the indicators tell you are getting 100% of the cores, what it's really means is that you are getting 100% of the 85 ~ 90% theoretical maximum you can achieve with the hardware you have.

I hope this clears things up for y'all.


How was Ethereum hard fork's replay attack was handled? 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)?

There's some history when it comes to ETH/ETC replay protection.

  How was this problem resolved for Ethereum?

Initially when ETH hard-forked to invalidate the DAO contract, both ETC/ETH networks did not implement replay protection for transactions. Instead, a split contract was written instead which relies on a split oracle built in Ethereum to identify if the contract was called on the hard-fork (i.e. ETH chain).

The contract logic is quite simple as you can see for yourself, it basically splits the original tokens and sends them into two different addresses depending on which chain the contract is called.

Nowadays, the ETH (hard-forked) chain has effectively implemented replay protection. So transactions executed on the ETC network will not be valid on the ETH network and vice-versa.

  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)?

No.

Two things are important:

The Ethereum foundation actually like the idea of forks, allowing different views in the community to co-exist. The Foundation only support one chain (ETH in this case).
Ethereum is a different type of Blockchain from Bitcoin at the moment. It contains contracts that could be automated to perform specific task. Which makes it easier to automate solutions for forks.

This post will be help explain how it was solved at the time https://blog.ethereum.org/2016/07/26/onward_from_the_hard_fork/


What is the incentive to broadcast the whole blockchain? What is the incentive to broadcast unprocessed transactions? Among the strengths of bitcoin is that it mostly allows all actors to act in their own best interest. There are some actions however of which it is not so clear to me what is the direct incentive other than some kind of idealism.

Obviously it is in a miner's best interest to immediately broadcast a newfound block, or blocks that validate blocks mined by him.

Is there a direct incentive to broadcasting the whole blockchain though (i.e. operating a full node)? Likewise, is there a direct incentive to broadcast all transactions to other nodes immediately? Naively I would think that it could be advantageous to a miner if other miners don't have access to some high-fee transactions.

Of course, for both it is necessary that enough nodes do it for bitcoin to function smoothly, but I am interested in the incentive for an individual miner.

Note that not all full nodes are miners, and that there are significantly more non-mining full nodes than there are miners (as in the vast majority of full nodes are non-miners).

  Is there a direct incentive to broadcasting the whole blockchain though (i.e. operating a full node)?

The incentive for operating an archival node that can serve the blockchain to other peers is that doing so helps maintain the network and thus gives value to the Bitcoin that you are mining.

  Likewise, is there a direct incentive to broadcast all transactions to other nodes immediately?

Yes. If run a full node which is not broadcasting transactions, then when you decide to make a transaction, it becomes immediately obvious to your peers as to where that transaction originated from. The incentive is to preserve your privacy.

Even with a delayed broadcast, you would still be risking privacy as your peers would like hear the transactions first from other peers, so as soon as they see you broadcast a transaction that they hadn't seen from elsewhere, it would be reasonable for them to assume the transaction came from you.

Yeah, let's say you (and everyone currently invested in bitcoin at the moment) decide you want to stop spending resources on mining and contributing to the maintenance of the blockchain and want to sell out your entire position and take your profits..

what happens to the system when/if the only owners of bitcoin leftover are non-miners or non-blockchain maintainers?

bitcoin has no central bank or government with a vested interest in its survival and integrity so if there's a "run-on-the-bank" so-to-speak, what happens? what's the security?


Full node or Full node third-party services pros and cons I'm setting up P2P Bitcoin website similar to LocalBitcoin for school project.
Before I go deep into this journey I'm doing some plannings.

I have lot's of questions in my head and have been studying bitcoin technology.
I would like know if its better to run full node on my server and execute RPC commands or should I just look for companies that offer such services to save me some time?

What are the  pros and cons of running full node
I will also appreciate recommendations for third-party services for Bitcoin P2P market

What are the pros and cons of running full node

it all comes down to the level of trust. Whom do you trust? Your own system, or someone else? And then, how much money are we talking about? Several low values, or monthly or yearly values?

For sure I recommend a full node. And yes, it has the disadvantage of downloading the blockchain (easily up to three weeks), and you need to have that infrastructure up and running. For this you gain the absolute security, that noone faked a block or a tx in the blockchain, that is assembled on your system. Also the level of privacy is higher than e.g. SPV nodes. A full node supports the decentralization aspects of the network. More full nodes, more tamperproof is the whole bitcoin eco-system.
Using RPC calls to your local bitcoin node requires then some developer knowledge, or a dev-team. That can add to costs in setting up your environment.

Using services like bitpay or similiar has the advantage of getting quickly started. This way you can start to setup your business, and later on, if you have really big values, you are still able to convert to a full node.

So from a risk perspective: when it is low values, go ahead with services from third parties, but when you achieve higher values (above monthly income), think about securing your environment with an infrastructure, that is under your own control.

There is no company offering reliable full node services(i.e. they have various rate limits). Best is to use your own node. Unfortunately the bitcoin nodes suck big time(i.e. bitpay insight is broken, bitcoind indexes only one address/wallet etc) so you will have to build a lot from scratch. If bitcoin is not a hard requirement I suggest you to look for a "localethereum" project. Ethereum has better software.


How can I avoid paying transaction fees? A bitcoin transaction requires paying a fee to the network, and that fee changes depending on network congestion. During busy times the fee rate may increase substantially, so how can a user avoid paying these fees in the first place?

Is there a way to transfer/import bitcoin from one address to another in order to avoid transaction fees?

(I'm posting this question because I was writing a reply to a similar question, and halfway through writing that reply, the question was voted closed)

Is there a way to transfer/import bitcoin from one address to another in order to avoid transaction fees?

No. It is not possible to move btc between addresses without publishing a transaction to the blockchain. However, there are some ways to accomplish a similar result (transferring/altering the ability to spend some coins), but I think every one of those ways will employ a different trust model than actually transacting on the blockchain. As a user, you must balance the level of trust you are comfortable with, against the need to save on transaction fees.

Some examples:

Off chain transactions using a centralized service:

This is how an exchange moves btc between accounts without incurring transaction fees. For example, when you buy/sell on a bitcoin exchange, a transaction is not actually published to the blockchain. Rather, the exchange will simply update their internal database, which keeps a ledger of all user account balances. As a user you are trusting that the exchange has a full reserve of all outstanding user $ and btc balances, and that they will not make an error in keeping track of your account balance.

Off-chain transactions by exchange of private keys

You can give someone bitcoin by simply giving them a copy of private keys for a funded address. In this situation, the recipient will need to trust that you do not own any other copies of the private keys, or that you will not spend the coins yourself if you do have a copy saved.

(as an aside, if you are sharing keys with a friend, and the coins are stolen by a third party, it may be impossible to prove to your friend that you did not simply steal the coins- and vice versa).

Off-chain transactions by exchange of private keys, which are provably not backed up

This is made possible by specialized hardware, such as that produced by OpenDime. In this case, as long as you trust that the OpenDime hardware functions as advertised, you can give someone a funded OpenDime stick and they do not have to worry that you might have a backup of the keys for those coins.

A signed transaction that is communicated off-chain

In this case, you could sign a completely valid bitcoin transaction that sends coins to your recipients address, and then send someone the raw tx data, without publishing it to the blockchain. The recipient would be able to publish the data to the blockchain themselves, but they will have to trust you to not sign and publish a different transaction using those same outputs in the meantime. This method would also only 'delay' the spending of the tx fees.

(I'm honestly not aware of any actual use-case for a scheme like this. It's probably a dumb idea that requires a lot of trust, but it is possible nonetheless)

Payment channels

In this case, two transacting parties can lock some amount of btc into a special multi-sig address, and then trade a limitless number of partially signed transactions back and forth off chain, with no tx fees, and no need to trust the other party will not steal your bitcoin. The parties involved can only exchange value up to a maximum amount (the amount they locked into the channel), but the channel can be bi-directional, so payments can be sent back and forth basically endlessly otherwise. This method still requires a transaction fee to open and close the payment channel, but that fee now account for a vast number of 'off-chain' transactions, instead of just one or two on-chain.

An implementation of this idea is the lightning network, it is currently live on the bitcoin testnet.

If you don’t care about your privacy, just use https://pro.coinbase.com/…

While they don’t allow to send transactions without paying fees, they will pay the fees for you…


Support sending bitcoins using webpage URL? Are there any Bitcoin clients or services that support sending bitcoins to a HTTP(S) URL instead of having to enter a Bitcoin address directly? (e.g. for donations)

Webmasters could include their Bitcoin address in a link element in each page (same for the whole site or different for each page, e.g. to account which page generated which donation):

<link rel="payment" href="bitcoin:…" title="Donate bitcoins, if my article was of help to you">

The href attribute should contain the Bitcoin address, using the bitcoin URI scheme.

The rel attribute should have the value payment. It’s defined as:

  RelPayment is a microformat for making exchanges of support (be it financial or otherwise) possible. By adding rel="payment" to a hyperlink a page indicates that the destination of that hyperlink provides a way to show or give support for the current page. For example to give financial support to the owner of the current page.

The (optional) title attribute could contain a small note, e.g. what the donations are used for, or who exactly would be the receiver etc.

Tools (Bitcoin clients/services, browser add-ons etc.) could extract the Bitcoin address by looking for a link with the link type payment whose URI uses the scheme bitcoin.
If one enters a webpage URL that hasn’t linked a Bitcoin address, the tool should throw an error. For security reasons probably only link elements should be parsed (instead of a/area), otherwise e.g. commentators could include their own Bitcoin addresses.

The client Electrum seems to support something like that (using a different method): Aliases:

Aliases may be server names (e.g. ecdsa.org) or email-like addresses (e.g. john.doe@ecdsa.org)
The corresponding Bitcoin address is retrieved by the client, using a descriptor located at a canonical url.
Aliases may be entered in the Electrum client, or used in Bitcoin URIs […]

Armory already supports donating with a syntax like this.  The syntax is as follows:

bitcoin:1ArmoryXcfq7TnCSuZa9fQjRYwJ4bkRKfv?amount=1.0&label=Armory%20Developers&message=Donation%20to%20Armory

See https://bitcoinarmory.com/ for the reference of where I got this from, it's at the bottom of the page before the QR code.

That's just an http link where it is using bitcoin: as a prefix similar to how email links are setup, it has the bitcoin amount, the label, and the the address all pretty clearly labeled here.


Safely convert paper wallet to encrypted online wallet I started investing a not insignificant part of my salary into BTC a few years ago. I created 10 paper wallets (using bitcoinpaperwallet.com) on a dedicated laptop disconnected from the Internet. I then stored them in my office drawer however I no longer feel safe due to potential theft/elements etc. and I don't have access to a safety deposit box.

I want to digitize them and use strong encryption so I can store them on a few different servers that I own for redundancy. I don't need to regularly withdraw BTC from these wallets as they are for investment, I keep a separate small hot wallet on blockchain.info for spending. I'm confused as to how I should;

a) Digitize the paper wallets. I dont want to have to  manually enter the private keys and make a mistake. Is there software I can run on the disconnected laptop that can scan the QR codes for the private keys using the webcam? I know blockchain.info does this but the laptop doesn't have Internet access.
b) Once I have the private keys in a digital format (either in a plain text file or some wallet format) what form of encryption do you recommend. I'm currently planning on using PGP with 8k RSA keys.

Any advice would be most appreciated.

Not completely what you asked for, but if you have a significant amount of money in bitcoin it makes sense to store them on a hardware wallet like trezor, ledger, ... . These cost 100$ or less and are totally worth it for ease of use and peace of mind.

I would sweep the paper wallets with mycelium and send the btc to your hardware wallet. This completely eliminates the threat of your computer being infected/hacked/etc. Since you have 10 paper wallets, I'm presuming the individual amounts might be ok to store on your phone for a few minutes.

Regarding storage, all addresses on the hardware wallet are generated starting from a 24 word seed. So you could write down 2 or 3 copies of this seed and distribute them in vaults/to trusted people. These 24 words can of course also be encrypted etc. If your hardware wallet breaks, all bitcoins can be retrieved by using these 24 words and a new compatible hardware/software wallet.

If you want to encrypt those keys, i would recommend using RSA-2048.
It is above military grade and will not be factorized in the near future (well, i'll take that as upcoming 15 years or so, who knows the computer technologies booms up?)


Why don't we have a help for Bitcoin Core CLI options in the same way as we do for CLI commands? There is detailed help for bitcoin-cli commands using for example:
./src/bitcoin-cli getconnectioncount help.
However, there isn't generally detailed help for bitcoin-cli options such as
./src/bitcoin-cli -netinfo help.
(Note the dash in front of netinfo with no such dash before getconnectioncount)
Is there a reason why there isn't the same help for bitcoin-cli options?
Jon Atack added on IRC:

If not is there an already planned way to add to the help doc and
would this be a good idea? For more detailed help than in
./src/bitcoin-cli -h
I was thinking it might be good to have a detailed help doc for
-netinfo either with help -netinfo or expand the existing one at
./src/bitcoin-cli -h | grep -A3 netinfo or add a doc/netinfo.md
file

This simply is a shortcoming that should be fixed.
David Harding added on IRC:

help <command> is for RPCs; -h is for a quick summary of CLI
parameters.  Extended CLI parameter help should probably be in a
manual page.


Can Circulating supply decrease? Looking at the historical data of Loopring, I noticed something strange.

On Jan 4, Market cap was $163,805,000 and closed price was $0.65. That means, circulating supply was around 252M.

On Jan 5, closed price increased to $1.03 BUT market cap decreased to $41,138,000. And this means, circulating supply went down to around 39M.

Shouldn't Market Cap increase when price increases?

Can circulating supply decrease? or is there something that I am missing?

Shouldn't Market Cap increase when price increases?

It depends. MarketCap = circulating supply x unit price

Giving : MC=10, CS=10, UP=1

Example of an increase in MC : MC=20, CS=10, UP=2

Example of steady MC : MC=10, CS=20, UP=0.5

Example of a decrease in MC : MC=5, CS=10, UP=0.5

  Can circulating supply decrease?

Yes circulating supply decrease, especially in centralized coins(controlled by individuals or corporations)

Example : Ripple decided to lock a huge number for XRP in mid 2017 which lead to unit price increase


How to see previous transactions? This question is linked to this one. I try to understand the bitcoin block by exploring and viewing every piece of information, since the blockchain is public and shared.

When the sender transacts some bitcoins to the recipient, he technically transact previous transactions. So in a transaction, it is possible to find successively all previous transactions. Where can we find this piece of information? (I remembered that I already saw this information on a website, I thought that was https://blockchain.info.)

You are correct all transactions other than coinbase transactions utilize previous transaction outputs. You can navigate those using any number of block explorers:

http://blockchain.info
http://blockcypher.com
http://blockr.io

And many more.

Try bitcoin visualization tool like https://www.blockseer.com


blockchain transactions dump file I am looking for hourly, daily, weekly, monthly and yearly blockchain transactions dump in csv or other formats. Any pointers would be really appreciated.


After being scammed, has anyone ever actually managed to recover their BTC? Like real world cash problems, we know that scams happen in the Bitcoin community at least as often if not more often for a variety of reasons (oversight, regulation, standards of security, street savvy, etc., or lack thereof).

Given little more than a receiving address and perhaps an email address (likely a one-time junk account) or stated location (may not be true), is there a recorded instance where someone who was scammed was able to recover their loss directly from the scammer?

This could be with police assistance or through communication among online services or people through taint analysis or chain tracking.

There have been many instances of coins being sent to the wrong address and then clues from the blockchain used to discover the recipient and thus recover the funds.  Goat's 400 BTC loss and subsequent recovery is the largest of these that I'm aware of.

There have been hints from the blockchain that have allegedly associated sockpuppet accounts to a repeat offending scammer.

I remember that Zhou Tong "figured out" his friend was responsible for the bitcoinica hacking and asked for the return of the bitcoins. IIRC, some were returned, but don't quote me on that.


What wallet / e-wallet is the most convenient for new casual Bitcoin users? I'd like to make small payments for business purposes through Bitcoin, so would like to know what the easiest method of getting setup to accept a Bitcoin payment is for a regular person, so that I can recommend it to those I want to pay.

Some options I see are:

Standard Bitcoin client
BitcoinJ
Instawallet
Flexcoin

These people will only be holding a few Bitcoin at most in their wallet, so security is not as high a priority as in other cases, but I would still like to avoid a Mybitcoin type fiasco where every one I pay loses their money.

Which method has the best combination of convenience in getting setup and security?

Sorry to dig up and old question but I just wanted to add a link to My Wallet provided by blockchain.info

I guess the thing that separates My Wallet from other e-wallet providers is that the site aims to feel more like an actually bitcoin client rather providing disposable addresses. I tried to design the site to be easy to use and it should seem familiar to anyone that has used PayPal or online banking. I will be adding more features soon which should be familiar to novice users such as invoices and monthly statements.

You can generate up to 200 different bitcoin addresses and are free to export the private keys at anytime. In fact if you already have an existing bitcoin address you don't even need to add your private keys at all. For more information about how the site works try the faq or browse the code.

Avoid online wallet services at all costs! None of them will ever be safer or more secure than holding the private keys yourself.

I recommend either the official Bitcoin client if you don't mind downloading the block chain, or if you have a smartphone, BitcoinSpinner.

With BitcoinSpinner, you don't have to download the blockchain and the private keys are stored on your phone so your funds are safe and it's really lightweight and easy to use, especially in a business environment for taking payments via QR code.


Is Cointellect a scam? I downloaded coin Miner from Cointellect.com on my PC and I started mining.
I have some questions:

Is the software a scam?
Has anyone gained real money from this software?

When I read forums, some people talk about scam and trojan viruses installed on their machines; others show money gained.

This is undoubtedly yet another scam. It's intent is the only question.

Your first port of call seems obvious; Google Is cointellect a scam?
Answer: yes.

Explanation:

Pooling the CPU resources of every miner using this software would be a fraction of the power for even the oldest ASICs.

As an analogy, the site is saying individuals need to dig an open cut mine with their spoons while mining rigs (ie 50ft tall trucks) are carting away pay dirt to process. Pool all the spoons you like, there's simply no feasibility of any reward - but assuming the improbable, if a block was mined, how is the ฿25 distributed? If you can't answer that then that's indicative of a scam.

As far as the "debate" about some users saying they've seen returns; this is how scammers operate. They use shills (fake positive reviewers) claiming profits which never occurred.

Whether the scam is fruitlessly using CPU to try and mine is possible, but it's astronomically more likely the software is a vector for Trojans to steal your Bitcoin. These types of malicious "mining" software are simply identifying newbie Bitcoin users, infiltrating the OS with a Trojan/RAT/keylogger, then stealing your wallet / private keys if/when they become available.

Assuming a Windows installation, you're basically screwed. The software likely already has your login info, passwords, private keys, credit card details; any and all are likely compromised. I'd immediately disconnect from the Internet and do a fresh install of your OS.

Please, research these things beforehand because so many of these services are popping up. Let's hope the Bitcoin Savings And Loan retroactive prosecution of running a Ponzi scheme sets a precedent and scares some would be scammers straight.

EDIT:

Virus analysis of software
SSL certificate owned by unknown
Company name similar to banking conglomerate but not that company

Take this info as you like. It's fact. Not libellous.

Tell that to the Congress we made our presentation at in Brussels Belgium, and our happy member's forum growing daily @ http://facebook.com/JoinCoIntellect

Then see our review of the conference on our post daily blog from there, along with our 24/7 support...

The definition of cloud mining? Simply put, cloud mining means using (generally) shared processing power run from remote data center which we do^ more ways than one, if you researched we are OPEN SOURCE explained HERE; http://cointellect.com/download/advanced


Does IOTA really have a Documentation? I hear a lot about IOTA, but on the official site I found very little.

I read the WP:
https://iota.org/IOTA_Whitepaper.pdf

but that's just concepts, I want to know details about software like "iotacore"

https://dev.iota.org/#

The link is broken.

can anyone tell me where I find reliable information about this  cryptocurrency?

Great IOTA tutorial playlist
https://www.youtube.com/playlist?list=PLmL13yqb6OxdIf6CQMHf7hUcDZBbxHyza

IOTA tools from the playlist
https://www.mobilefish.com/services/cryptocurrency/cryptocurrency.php

IOTA and NodeJS tutorial
https://youtu.be/Z-NN0rRcwY0

Repository for above tutorial
https://github.com/iota-community/iota-workshop

IOTA is still running in beta and need to wait for the official documentation to roll out in the coming few months as mentioned in the link.

check this link for IOTA beta documentation: https://iota.readme.io/v1.2.0/docs/what-is-iota


GUIminer, unnable to connect to pool I'm getting a connection error, or just a "connecting..." message that doesn't stop. though the connection on my end seems to be fine. This is a printout of my console. If there is already a fix for this, would someone please direct me to it? This is a screenshot of my console. I'm connecting to slush's pool if that helps.
http://i.imgur.com/vcdAY9k.png

use the GUIMiner-scrypt instead .... I could not get the guiminer to work.


Does Satoshidice benefit the wider Bitcoin ecosystem? Aside from the entertainment benefit players get from the service, does it in any way help the Bitcoin ecosystem to have a large churn of small transactions?

There is value added by this service:

  Over the past 15 years, downtown Las Vegas has seen its slot machines
  tighten from a 1996 average of 4.8 percent to 2010’s 6.4, a “cost”
  increase of almost 32 percent. That means, on average, players see
  fewer jackpots and spent less time on their machines. In short,
  they’re not getting a lot of bang for their slot buck.

http://weeklyseven.com/news/2011/march/17/loosening

Online wagering can be a little lower house edge, but rarely will you find a house edge of just 1.5% like SatoshiDICE offers and the 1% that BitLotto offers.  Here's some background:

http://www.beatingbonuses.com/slotgames.htm

To play SatoshiDICE you need bitcoins, so that means there will be additional activity at the exchanges (both in purchases of bitcoins and cashing out by those who lady luck was nice to).  The player base won't be just existing bitcoiners as this payout level is such an attraction it will spread by word of mouth -- or virally even.

Most Bitcoin software, websites, documentation and media or press has been for an English-speaking audience.  With translations for multiple languages, Bitcoin will reach for the first time many users who would not otherwise learn of it.

Of course, every bitcoin that is held by a SatoshiDICE gambler is a bitcoin that is not sitting in a trader's wallet, waiting for the first hint of a selloff before it gets dumped (i.e., volatility is lower when the coins are not concentrated as much primarily with those speculating.)

After reaching a level where using Bitcoin becomes comfortable, those gambling at SatoshiDICE might find other goods and services that their bitcoins are useful for instead of just cashing out.

Additionally, with this unprecedented success for a Bitcoin startup there will be competition.  The technique employed by SatoshiDICE (payouts using same coins as the wager, thus can be paid out using 0/unconfirmed) is novel but easily replicated.

SatoshiDICE is a for-profit venture, and a chunk of those profits will likely be reinvested back into that business (perhaps building a mobile app for it, as an example), and/or other Bitcoin-related endeavors.

The blockchain pruning feature was something Bitcoin's developers hadn't had as top priority but with this level of growth and added data to the blockchain that may become top-of-mind.  This may be a feature that will help Bitcoin and SatoshiDICE might be responsible for having it occur sooner than it might otherwise have.

For Bitcoin, SatoshiDICE has win written all over it!

No, SatoshiDICE seems to be generally illegal, which only harms Bitcoin's reputation - and even in jurisdictions where it might be legal, gambling is generally regarded poorly. Additionally, it fills the blockchain with bloat unnecessarily and is easily exploited.


Too late to claim BCH and BTG I recently came back in from the crypto wilderness and heard about the BCH (Bitcoin Cash)and BTG (Bitcoin Gold), which were given out when the currency forked. I have 2 BTC's which I have started to update.

I was wondering if it's too late to claim the BTG and BCH?

There is no deadline to claim these forks. If you have access to the private keys of the addresses that owned Bitcoin during these forks, you own those coins too.

No, its not too late. if both coins were held before the fork, then you can claim them.


What multi-sig wallets are there for Android/Jolla? TL;DR: What wallet apps are there for android (or sailfishOS) that has "true" support for multisig?

Requirements/rationale

Thinking a bit, if I'm to possess serious amounts of bitcoins, I want a well-secured savings wallet - or, eventually just a well-secured savings address.  After some thinking, the requirements seems to be:

1) it should not be easy to withdraw funds, withdrawing should either involve multiple people or the passing of a time window.

2) the bitcoins must be secured against my death

3) the bitcoins must be secured against loss/theft of a private key

Solution: multisig

One stupid-simple solution would be to generate a single private key, write parts of it down on 5 papers in such a manner that any three out of five papers needs to be recovered to learn the full private key, seal the papers in envelopes, and then distribute those envelopes to people/locations I trust, instructing them to keep them in a safe place and hand them over to my next in kin in case of my death.  It actually seems like a decent way to solve this.

Anyway - why bother with such obscurity when bitcoin supports multi-sig transactions out of the box.  Even for daily usage patterns multi-sig seems like a good idea.  As for a savings wallet, I think that in the start it would suffice with 2-of-3 - me and my wife, plus a third arbitrator that can help us out in case of death or divorce.  Armory seems to be the go-to-wallet for the Linux desktop - but I'd like access from mobile devices as well.

Apps tested so far

copay - it could do the trick, but it seems to be a "lock-in platform" - all signing parties needs to have copay installed.  That's not acceptable.  For one thing, I want a platform neutral solution, like a savings wallet I'd mainly access from a "proper" laptop/desktop.
"bitx smart wallet" - what kind of beast is this, requiring me to verify my email before use?
greenbits/greenaddress - seems like their "multisig support" is very narrow; only 2-of-2, with their servers acting as one of the signing parties, and offering to sign against 2f-authentication.  Totally not what I want.
yet another android wallet that came up when searching for "multisig" - but it apparently had no support for multisig.

If I go slightly of topic I will recomend you to incorporate a solution using a law of trusts if your law system has it incorporated.

I am still about to recommend you Copay wallet as it is open-source. You can even rebrand it to your own company.

You have to remember that you can use HD wallet with Copay. You can use Bitcoin Trezor with copay so you have strong security. And all of this could be saved to a secure place.

Use coinb.in
It allows you to make multisig addresses from public keys, create transactions to spend from multisig addresses, sign transactions, verify transactions and broadcast transactions. You can run the website offline with full functionality (except broadcast of course).


Why is a GPU a better tool for bitcoin mining than a CPU and is an FPGA better than both? I was looking into the best tools for bitcoin mining and found out that GPUs are a better tool for bitcoin mining than CPU's. What is the reason for this?

furthermore, I found dedicated chips that can only be used for bitcoin mining. How come that these relative small chips are far superior to the best intel/amd/Nvidia chips?

Bitcoin mining is essentially just the repeated calculation of sha256 checksums. Given that sha256 is a fairly simple algorithm that uses only basic integer calculations absolutely any processor core should be capable of churning out sha256 checksums very quickly and any added complexity beyond the basic instructions required for sha256 is wasted. To that end the ideal candidate for mining hardware should have the least complex cores necessary for sha256 but the largest possible number of cores.

Your CPU has probably between 2 and 8 cores, each of them insanely complex. Your GPU has comparatively simple cores, but probably has over a thousand of them. Still, even GPU cores are more complex than they need to be for sha256, which is where FPGAs and ASICs come in.

An ASIC is a custom chip, designed to do only one thing - in this case it's designed to perform two rounds of sha256. It has only the necessary components for its one and only purpose. An FPGA is a device commonly used to prototype ASICs, it's basically a chip whose components can be rearranged to mimic another kind of chip. Because they retain this multi-purpose capability FPGAs are significantly less efficient than ASICs.

The only (temporary) benefit we saw from FPGAs is the cost curve. FPGAs are pre-manufactured consumer devices, you can buy just one of them and they usually don't cost a huge amount of money. An ASIC is something you have manufactured, and the minimum order size is usually absurd, requiring a huge up-front investment to get your chips made.

Different chip architecture make it designed to do Bitcoin mining more effectively


How to get Bitcoins without having a bank account? I'm an 18-year-old guy who wants to get some bitcoins but I don't have a Bank account yet.

I've been looking at some websites, such as bitstamp.net or blockchain.info but they seem like they are having problems (each one with its own problems).

What would be a fast way of converting cash into Bitcoins or cash into PayPal into bitcoins? (I don't know wich method can be used to get bitcoins, I'm really new to this.)

Read up about chargeback, this is unfortunately a huge problem when you exchange from bitcoins to 'PayPal dollars' and other online currency.

However, you can buy bitcoins with cash: https://localbitcoins.com/

Going through a mining leasing service is now the best option to obtain Bitcoin without a bank account. Some services claim to pay out more than 200%, but if they did that then why would they be leasing the power to you instead of pocketing the currency themselves?? The honest services aim for anywhere from 70% to 150% your invested amount, paid out after it's been converted to Bitcoin and transferred to your wallet.

These services are a huge bonus for anyone that doesn't want to deal with an Exchange or the privacy issues there - They get hacked quite often. It's also a way for people to obtain Bitcoin or any crypto-currency that don't have access to an Exchange for any reason.

You can pay with Paypal through most sites, although you'll probably want to do business with one that accepts credit cards as well. The leased mining services that accept CC payments are heavily regulated and are very likely to be legit, especially if they are located in the United States. The scrypt mining services, ones mining Litecoin, Dogecoin, etc. are the most profitable - They usually can pay you out in any cyrpto-currency coin, including Bitcoin.

I hope that helps!


Are there any works of science fiction out there that relate to blockchain technology? It feels like science fiction is lagging behind Bitcoin and the blockchain technology that is powering it.  Are there any writers who have discussed similar technology in their stories? Even in the past 5 years?

See also the same question at the ethereum forum

Found one: Stephenson's Cryptonomicon.

See also Digital Currency: ten years before Bitcoin, Neal Stephenson's Cryptonomicon

The on going science fiction TV series Almost Human has mentioned Bitcoin in several episodes. Video and Discussions. In the show, Bitcoin is considered as a well recognized way for anonymous money transafer. And 5000 btc will be a fortune the size of a country.


What can be done to mitigate the risk of a Finney-attack? Related Question: Would a reduced block generation time make the Finney attack more difficult?

I understand that the Finney-attack is the main reason why accepting a zero-confirmation transaction should be avoided for transactions of significant value or at on-demand websites that "ship" instantly.

Suppose a merchant needs to accept transactions near-instantly - what can he do to mitigate the risk of this specific kind of attack without relying on any third-party (escrow-like) service? Are there any practical strategies like checking large pools for the transaction, systematically delaying the acceptance of the transaction, etc. that actually work? What could be changed within the Bitcoin-client to lessen the likelihood of this attack-vector?

The key to understanding why the Finney attack isn't really that big of a deal is understanding the business case for accepting 0/unconfirmed transactions. An online merchant doesn't usually have to accept such transactions since they probably do batch-shipping anyway. It's not required from an integration standpoint since the API includes many options to simply not return transactions without confirmations. The only business case that requires the acceptance of 0/unconfirmed transactions is when your customer is standing directly in front of you and won't be around for 10+ minutes. In such cases, a Finney attack isn't feasible and here's why:

Imagine I'm a scammer wanting to use the Finney attack against you, the honest merchant. I've spent a few grand and bought myself 3 GH/s worth of Radeon 5830 rigs. This number isn't arbitrarily chosen, I specifically picked it to make for easy math - 3 GH/s will net you about 1 block per month at current difficulties. Given that actual brick-and-mortar stores are closed for about 8 hours per night on average, this means that 1/3 of my found blocks will occur outside of business hours so on average I get a chance to double-spend with a Finney attack every 45 days.

Now as with all mining, there's no telling when you'll hit that lucky block so if I'm dead set on executing this attack I have to stay hypervigilant because once every 45 days I'll get an alarm of some sort telling me to go spend money at my target's store. I have to get there quickly because if I don't make my purchase and remotely trigger the release of the block fast enough, that block will get solved by some other miner and I'll lose my chance. So let's say on average it takes me 5 minutes to get somewhere, pick something and make a big purchase - I've got a 50% chance of failure, so now I'm able to execute my attack about once every 90 days.

Mining isn't cheap - my 3 GH/s setup draws something like 2 kilowatts, add in another 800 watts or so for cooling and at my local electricity costs it runs me about $8 a day to try for this attack. Multiply this by the 90 days it takes on average for me to be successful and I have to be successful to the tune of $710 just to break even. I'd make better money mining! Keep in mind that I've spent 16 hours a day every day for three months waiting for that alarm to go off too, so even if I double-spend $1420 (double my costs) I still only make $236.67 per month for my trouble - 49.3 cents per hour.

Oh and once you've made the purchase there's still the gap between then and releasing the block. If a block is found during that window, you've actually spent that money now. This particular attack is not without risk.

So there's something of an answer - not how to mitigate the attack but why the attack doesn't really matter. Online merchants don't need to accept 0 confirmation transactions since your stuff probably won't ship within 10 minutes anyway and brick-and-mortar merchants add a delay to the transaction process that makes the attack unfeasible. Even without the delay, the transaction would have to be positively huge to make any sort of profit and the attacker still stands a large risk of actually spending the money anyway. I don't really see this taking off.

What can a merchant do to mitigate the risk this specific kind of attack?

Wait for a few confirmations.


How do cloud hashing companies profit? (leasing hashing power) I think I'm missing something. There are a bunch of cloud hashing companies that lease hashing power. Let's take cointellect for example. They have contracts from 10 days to 24 months. If I buy a 10 mH/s of hashing power from this company for 99 euros, they guarantee a minimum of 2.2 euro daily return which makes 180 euros in return for my initial investment of 99 euros in the 3 month contract. How is this profitable for both me and the company? What's the math behind this?

When you're calculating the profit from Bitcoin mining, you take into account the current bitcoin price, how much hashpower you have, and the current difficulty.

Difficulty rises over time. (Generally speaking.) Between Jan '12 and Jan '13, difficulty rose by a factor of 2.9x.

Between Jan '13 and Jan '14, difficulty rose by 407.2x.

Between Jan '14 and now, difficulty has risen by 33.3x.

Unless they're guaranteeing 2.2 euros per day over the course of the contract, in which case they're either morons or liars. (If you really could guarantee that kind of return, investors would be all over you.)

Of course, as David Schwartz notes, it could also be a scam. They could give you good returns, then vanish after lots of people invest.

I find a summary the best way to explain this:

Company: +£99 from you.
The company do not pay out anything but costs for power. Bitcoin 'creates' the money.
You: +£All your earnings.
10Mh/s will not generate anything, 10Gh/s maybe...


How to convert encrypted wallet.dat to decrypted? (Yes, I know the password) I don't want to spend transaction fee for transferring coins to unencrypted wallet.dat.

What should I do?

The easiest way is to export your private keys using the dumpprivkey functionality.

  DumpPrivKey: returns the wallet-import-format (WIP) private key corresponding to an address. (But does not remove it from the wallet.) Bitcoin Developer Reference

Do this for each address that is storing bitcoin (use listreceivedbyaddress to view all addresses with funds)

  ListReceivedByAddress: lists the total number of bitcoins received by each address. Bitcoin Developer Reference

Then create a backup copy of your wallet.dat file and then remove it.  The next time bitcoin-qt runs it will create a new empty unencrypted wallet.  Now you can use importprivkey to restore your funds.

  ImportPrivKey: adds a private key to your wallet. The key should be formatted in the wallet import format created by the dumpprivkey RPC. Bitcoin Developer Reference

You can make a paper wallet from actual addresses, then delete wallet.dat, create new one and import paper wallets on created unencypted wallet.dat file.

But you must to remember about the "change address" mechanism because you can lose your bitcoins forever.


Tax implications in Canada of buying and selling Bitcoins? What taxes should be paid in Canada on Bitcoin transactions? Has anyone gotten official advice on this?

Is it relevant whether the Bitcoins were mined, received as payment for services, bought and then sold for a profit, or freely donated?

Is it relevant whether the Bitcoins are exchanged for CAD or exchanged directly for goods?

Is it relevant where geographically the buyer and seller are?

Taxing authorities consider currencies or goods received in trade to be taxable income. Bitcoin would fall in the same category as foreign currency or barter, and would be taxable.

In Canada, barter is sometimes exempt from taxation:

"According to the Revenue Canada document T-490 (Barter Transactions): if the person(s) bartering is an employee, and not a business owner, they may exchange non-business-related services or goods "occasionally" without being subject to taxation. However, if the goods are business-related, or the exchange is "a regular habit" it falls under the category of taxable income, regardless of his employee status." source

Here's the Revenue Canada bulletin on barter and taxation:

http://www.cra-arc.gc.ca/E/pub/tp/it490/it490-e.txt

Trading bitcoins for CDN$ is also non taxable if occasional and if your are not doing it as a business..


how to activate BIP148 in bcoin configuration I cannot find any documentation about activating BIP148 on a bcoin node. Is there anything similar to BIP151=true in the bcoin.conf or is it enabled by default?

You can Update their node software to a BIP148-enforcing version; or
Run a BIP148 border node to filter out invalid blocks, and update their existing mining software to produce blocks with version 1 bit enabled, to vote for Segwit activation.
Signed binaries can be downloaded at BIP148

First, install all necessary dependencies which are mentioned in the official Bitcoin build instructions details UASF


Displaying price in BTC based on USD exchange rate This is a pretty classic programming question, but I think it is a very common one for the Bitcoin community, and would be helpful to have the code publicly available.

My preference is for a php script.

Bitpay publishes it's exchange rates here: https://bitpay.com/api/rates

If an item is $10 USD, how would I do the following?

1) extract the BTC/USD exchange rate from the array at this URL
2) Define the price, then divide by the exchange rate
3) Display the BTC price in an HTML page?

Save the code to a PHP file in the web directory:

<?php
  $url = "https://bitpay.com/api/rates";

  $json = file_get_contents($url);
  $data = json_decode($json, TRUE);

  $rate = $data[2]["rate"];   //$data[1] is outdated now, they have updated their json order. This new number 2 now fetches USD price.
  $usd_price = 10;     # Let cost of elephant be 10$
  $bitcoin_price = round( $usd_price / $rate , 8 );
?>

Price: <?=$usd_price ?> $ / <?=$bitcoin_price ?> BTC

<?php
$url = "https://bitpay.com/api/rates";
$json = file_get_contents($url);
$data = json_decode($json, TRUE);
$rate = $data[0]["rate"];
$rate1 = $data[1]["rate"];
$rate2 = $data[2]["rate"];
$rate145 = $data[145]["rate"];
?>
BTC/USD: <?=$rate?>

BTC/EURO: <?=$rate1?>

BTC/GBP: <?=$rate2?>

BTC/VND : <?=$rate145?>

I edited the code from first answer and this one is work well


New wallet per customer, or new address? So I'm in the process of starting a new service, but want to make sure I build the foundation correctly from the start. When customers deposit to their user account on my service, I need to understand whether I should be using one giant wallet with a new address for every customer and assign that address in the database against their user, or if I should generate a new wallet (with, presumably, new seeds) on signup for every customer, so each customer has their own unique wallet. What is the best course of action here? One thing to be aware of is how the backup process will go, and any potential race conditions (say someone generates themselves an address and sends coins, but the server gets wiped out and the backup doesn't have that last 10 seconds of activity, so the address that was generated can't be tied back to the appropriate user).

If you are looking to accept deposits from your customers then you should create one deterministic wallet using software like electrum and the install the extended public key aka xpub aka master public key (MPK) on the server. Then from that you can generate all the addresses you need.

The above creates a watch-only setup where you can generate addresses to receive bitcoin but not spend. So in case someone compromises your server they learn your entire transaction history but they can't steal from you. In order to spend the money you need to use the seeded wallet on your PC.

In order to associate addresses with users you would make a note of it in your app's database.

If you want to associate addresses with users in some deterministic fashion then you can assign each user an ID number and a counter which will serve as an address index. Then you can devise an appropriate derivation path that incorporates those two things. So for example Alice could be user ID 5430. Alice's deposit addresses are m/5430/i where i is the counter in the database. First Alice address would be m/5430/0, second would be m/5430/1 and so on. The user ID would not change once a user registers so even with slightly older backups as long as you have the user ID you can increment the counter until you get to the correct one.

The best thing to do is make sure that each customer has their own wallet, with a recoverable phrase.

You mentioned you are using a server, which is unwise as hackers will be looking at that as a big bull's eye.

It sounds like you are making an exchange.

So what they do, is they have receive addresses which are real and on the blockchain. Each user is assigned an address where they can receieve X amount of BTC.

The send addresses however, are in the database, and the database keeps track of how many BTC you have internally.

When you ask to send BTC to someone, the database checks whether that someone is also in their database based on the toAdress, if so, then just minus amount from you and add amount to other person. This happens off the chain.

If not, then they minus the amount from you and send the BTC from one of their own addresses.

You should get someone to build your system for you, as you are dealing with people's finances, and one wrong move could leave you like Mt. Gox

Good luck!


What's the most popular Namecoin exchange? There are several Namecoin exchanges listed at official wiki and Bitparking seems to be the oldest, but which one is the most used?

Almost everyone seems to use the Bitparking Namecoin Exchange.


Is it possible to use bitcoin as interplanetary money/store of value? Let's say humans have finally made a successful colony on Mars, how useful would bitcoin be to transfer value between Earth and Mars?

And if it won't work with the current implementation, what would need to be changed in order for btc to be used interplanetary?

Assume there is no Mars cash or any monetary system, they just decided to use bitcoin for everything. It however has to be on the same blockchain that Earth is using.

Possible problems to consider:

how would mining work? Lets say a miner on Mars and a miner on Earth both solve a block at the same time, because of ~8 minute delay between the two planets who would get the reward and how to deal with such a problem?

NOTE: I will be updating and modifying this questions to make it more concise and to the point.

Let's say humans have finally made a successful colony on Mars, how useful would bitcoin be to transfer value between Earth and Mars?

If you're talking about the Bitcoin blockchain in its current form, it will restrict mining to one of both planets.

Bitcoin's assumptions include a block propagation time between miners is negligible compared to the interblock time (10 minutes). We've already seen the effects of a few seconds block propagation time on Earth: miners being forced to build upon each other's work without validating, to avoid orphaning during that time. This incentive encourages centralization, hurts Bitcoin's security (especially for light clients), and makes mining (even) less permissionless to enter.

The distance between Earth and Mars can be up to 401 million km, when they're on opposite sides of the Sun. Following the laws of relativity, it is fundamentally impossible to communicate between them in less than 22 minutes in that case. A propagation time of 22 minutes would utterly destroy any ability to mine on both sides. As there is a delay of 22 minutes before Earth can mine on top of a block created by Mars, or the other way around, but not when a planet mines on top of a block created by itself, you would end up with an almost persistently forked chain between the two. The slower planer would eventually always switch over to that of the faster planet, making the faster planet win far more blocks than proportional to its hashrate. Effectively, the delay between the two planets turns mining into a race rather than a lottery.

  And if it won't work with the current implementation, what would need to be changed in order for btc to be used interplanetary?

The above issue could probably be solved by using a chain with a ~1 week interblock time rather than 10 minutes, to compensate for the larger propagation time.

If we're fine with mining being controlled by one of both planets (effectively giving that planet the arbitrarily censor the other planet's transactions), it would probably work fine.

There are other issues though; another problem is partitioning. Bitcoin strongly relies on peers in the network to be able to communicate without ending up on their own islands of connectivity. There would need to be multiple independent communication links between the two planets to avoid a partition between Earth and Mars. If mining is knowingly on one side, the worst effect of a connectivity failure is just the lack of ability to see confirmations on the other side, though it may take hours (=a few roundtrips) to notice this.

Really, just an internet connection (obviously a computer too) so you can connect to all the nodes and keep up to date with the blockchain.

Or if you use a wallet service then just an internet connection to get to any available wallet on the market.

But also in order to liquidate Bitcoin into mars-cash you would need services to convert BTC to mars-cash. Unless you wanted BTC to be the mars-cash.


Export wallet from Multibit to Electrum So, MultiBit is not updating the transactions in my wallet, I can see the transactions in the blockchain etc, so the money is there but its just not quite working...

I'm hoping to load that wallet with another client, and have been looking at Electrum.

I read another post on here but it seems to be for an older version and while it tells you how to export keys, which I've done, I can't work out how to import it in to Electrum properly.

Can anyone help me out?

In the current version 2.8.3 of Electrum it's very easy to import Multibit wallets (meaning, migrating from Multibit to Electrum). An important reason to migrate is because Multibit (not HD but the classic one) does not allow to change network fees, which makes it very hard or even unreliable to move funds.

Select wallet in Multibit and choose Tools > Export Private Keys and export without password to a .key file.
Open the .key file with a text editor (e.g. Sublime Text) and copy the private key(s) from the text file.
Create a new wallet in Electrum from menu File > New/Restore, give it a name, a location to save and create as Standard Wallet (other options may also work but haven't tried).
When asked for Keystore, choose Use public or private keys. In the next screen, you can paste your private key(s) from step 2.
You now have a Electrum Wallet with the addresses previously used in Multibit and you can send/receive BTC from this wallet.

Note: The addresses will still be accessible from Multibit, since you can use the same wallet (private keys) from various apps/wallets. I use Multibit now as 'watch only' and not transfer anymore from it.

Sorry to answer an old question but just in case someone needs a really easy explaination like me:
https://www.youtube.com/watch?v=E-KcY6KUVnY


What are the pros and cons of Ripple's consensus as compared with Bitcoin's proof-of-work? One of the major differences between Bitcoin and Ripple is how they process transactions. I can think of three ways in which Ripple's "consensus" scheme is superior to Bitcoin's proof-of-work:

Less energy-intensive
No 51% attack
Faster transactions

What are the other pros and cons of Ripple's consensus as compared with Bitcoin's proof-of-work?

The big advantage on the Bitcoin side is that its technology is now well-proven. Ripple's consensus system is the newcomer. Ripple was designed by people who had the benefit of seeing exactly what Bitcoin was doing and its strengths and weaknesses.

Ripple's consensus process can validate a transaction such that irreversibility is reasonably assured much more quickly. When a validator processes a transaction it signs the resulting final ledger. Those signatures are provided within seconds.

Bitcoin's proof of work scheme isn't path dependent. Ripple's consensus scheme is. This has advantages and disadvantages on both sides. Because proof of work is not path dependent, someone with sufficient hashing power can rewrite the past. However, the lack of path dependence also means that no state is required to determine the right chain. The rule for the winning chain is very simple -- the valid chain with the most work wins.

The biggest difference is how trust works. With a proof of work scheme, you must trust the majority of work. So long as the majority of hashing power remains in the hands of a large number of disjoint organizations, that's fine. However, if hashing power become consolidated, it's not clear what the fix would be.

With Ripple's consensus scheme, you choose who you want to reach a consensus with and declare the system unusable if you cannot. One advantage here is that you can reliably detect if you can't reach consensus. With Bitcoin, if the Internet splits in half and you're on the side with less hashing power, you can only infer it as a statistical probability. With Ripple, if you're not reaching consensus with people, you know it immediately.

Another advantage is that if you ever do have an attack or disruption, you have signed cryptographic proof showing who did it and what they did. You can simply stop trying to reach a consensus with them and then they would have to start over from scratch to attempt such an attack again. Because the effort required is so great and the payoff so low, it's much less likely people will try.

The disadvantage here is that UNLs (lists of who you want to reach consensus with) must be maintained and if your UNL is broken, you can fail in various ways that get worse the more broken your UNL is. The downside of being in control is that you can shoot yourself in the foot. The upside is that you can do something if someone else tries to shoot you in the head.

Bitcoin could fairly easily adopt some of the principles of Ripple's consensus scheme and gain many of these benefits. For example, mining pools could sign a statement indicating which chain they are building on. In the event of a network split, this would make it rapidly clear whether you were still on the same chain as those pools. In the event of a bug-induced chain split, you'd quickly know that something was wrong and would be able to stop relying on transactions automatically rather than having to wait for a manual warning to go out.

"(Ripple can not be attacked by 51% attack"

That statement is wrong i would believe? Ripple is run by one single entity; the ones who made ripple. Ripple is then technically NOT decentralized like bitcoin. Ripple would then be incredibly weak against external violence that could want to stop or damage their service. Like mean men with guns from a invading government. Invading government could be our own government gone rouge or a foreign government invading.

Bitcoin on the other hand is decentralized and extremely resillient towards any such force of external violence.

Ripple is also pre-mined, and all coins are in the hands of the ones who made ripple, unlike bitcoin which coins are rewarded randomly to the miners.

Ripple can then shortly put be equally (dis)trusted as much as any other already central-governmental issued fiat currency.


Better Capacity with More Nodes In regards to the scaling debate, transactions per second etc. I’m curious, and I don’t often see this mentioned. But why not add more nodes to the network to alleviate some of the load?

I’m pretty certain there’s a good reasons why not, but would actually like to know?

The number of nodes in the P2P network is unrelated to scalability. Due to the entire validating network operating in lock step, they all do identical work independent of their peers no matter how many of them exist in the system. One node, a thousand nodes, a million nodes all operate at the same effective speed (and the limits of the network are the same). Adding more peers actually worsens the load somewhat, as you increase the total bandwidth necessary to get the transactional data to everybody in the network quickly.

the number of transactions capable of processing depends on an agreement among the community to not make blocks larger than 1mb.

nodes validate and relay transactions, but they dont register them into the blockchain.

as such, adding more nodes might lower the latency when distributing transactions, but it does not increase capacity to process transactions on the blockchain.


Slow synchronisation bitcoin-qt - bread wallet I have used bitcoin-qt for a while, but I have read now there is bread wallet for iOS more secure than any OS X wallet, is this true ?

I didn't update it for a while and now it is like 60+weeks behind and it will take a year or so to get it up to date... I made bitcoin transfer to someone on last thursday (4 days ago), it still does not show up, I can see in my log it as payment but with 0/6 confirmations (so I quess I need to update my wallet before transaction going out?)

I installed bread wallet to my iPhone, however I don't know how I can move my bitcoin qt data to it ? Breadwallet asks for recovery code OR new wallet, how I can synch wallets ?

You need to import your bitcoin-qt private key(s) into breadwallet.


Bitcore explorer insight testnet initialisation I am using bitcore explorer and I want to initialize insight api in testnet.
It has the following code.
I try var insight = new Insight('testnet') but it is not working.
What value for url should i input so that  Networks.get(url) === testnet

function Insight(url, network) {
  if (!url && !network) {
    return new Insight(Networks.defaultNetwork);
  }
  if (Networks.get(url)) {
    network = Networks.get(url);
    if (network === Networks.livenet) {
      url = 'https://insight.bitpay.com';
    } else {
      url = 'https://test-insight.bitpay.com';
    }
  }
  JSUtil.defineImmutable(this, {
    url: url,
    network: Networks.get(network) || Networks.defaultNetwork
  });
  this.request = request;
  return this;
}

Try this

const bitcore = require("bitcore-lib");
const Insight = require("bitcore-explorers").Insight;
insight = new Insight(bitcore.Networks.testnet);

then do the rest.


Can I transfer Bitcoin from Binance to an Electrum Wallet? I wanna be sure that it's possible.
I want to transfer Bitcoin I bought on Binance for trading purposes, to an Electrum wallet. Is this possible? If yes, can you explain me how to do it?
Thank you very much.

Yes it is possible, as long a Binance is willing to let you withdraw your coins.
Steps:

Open your electrum wallet. Open the 'Receive' tab, and copy the 'receiving address' to your clipboard.

Open Binance. Navigate to the page where you can initiate a withdrawal.

Paste the 'receiving address' from Electrum into Binance withdrawal form. Be sure to triple check that the address you pasted into Binance is exactly the same as the address that is showing in Electum

Submit the withdrawal to Binance, and then wait until they send you the coins. You will see confirmation of this in the Electrum wallet, as long as it is properly synced with the network.

NO, It is not possible.
You will ge the error message: The address does not match the currently selected network, it is recommended that you switch to another network.
Bitcoin or Etherum may even work, but at riddiculus fees (21,64€ for transfering 40€)


How can I recover a blockchain.info wallet from a 17 word phrase? I have a wallet at blockchain.info which I've opened about 4 years ago.
Right now I cannot access it. It looks like the site is sending me a verification email, but sadly I don't know which address it uses.
If I use the "I've lost my 2FA Device" option, I have to enter my mail, but it keep telling me that the mail address is not correct (I've tried my main mail and 3 other mail addresses that I've used to use).
If I use the "I've lost my Wallet Password" option (although I have the password), I have to enter a 12 word phrase. I have a 17 word phrase and I've tried to use the first 12 words and the last 12 words, but no luck - I cannot even press the "continue" button.
I've contacted the site's support a few times but haven't got any answer at all.

Is there a way for me to recover my wallet directly from the 17 word phrase?

Blockchain.info's legacy wallet phrase decryption is here:

https://blockchain.info/wallet/forgot-password

The updated blockchain wallet only has a 12 word phrase. I had this same issue a couple of months ago. Try this link, enter the 17 word phrase and you will get your password: https://blockchain.info/wallet/forgot-password


Funds not received in wallet I have requested funds sent to my Electrum Wallet receiving address, but have not received over a week now. According to the Blockchain ledger the funds are shown as "Unspent", help needed

If you used the receive tab and created a payment request but did not give that request to anybody, you won't magically receive funds. You cannot just "request funds" and expect Bitcoin to be magically sent to your wallet; that is not how Bitcoin works, it is not something that is magically given out for free.

If you gave someone an address to send to or sent them the payment request but that person still has not sent you money, then you should contact them and ask them why they did not send you funds yet.

If the sender has sent you the funds but you do not see the transaction in your wallet nor do you see it on a blockchain explorer, then the transaction has not confirmed and has likely been dropped from the network due to low transaction fees. If you do see it on a block explorer and it is unconfirmed, then wait for it to confirm or to drop from the network (i.e. you don't see it on block explorers). If the transaction cannot be found on block explorers, ask the person who sent you the Bitcoin to send the Bitcoin again but include a higher transaction fee. Or have them rebroadcast their transaction.


Who specified the Bitcoin protocol? I went through the original paper by Satoshi, which outlines the Bitcoin protocol. However, the paper is a high level overview of Bitcoin, and does not specify important parts of the protocol.

Who specified the details of the Bitcoin protocol? Which person or group is in charge of defining the standard of the protocol as of now?

However, the paper is a high level overview of Bitcoin, and does not specify important parts of the protocol.

That's true, and Hal Finney noted this when the bitcoin paper was published to the metzdowd cryptography mailing list. (The Bitcoin paper was published before the Bitcoin source code.)

  Unfortunately I am having trouble fully understanding the system. The paper describes key concepts and some data structures, but does not clearly specify the various rules and verifications that the participants in the system would have to follow.

  Who specified the details of the Bitcoin protocol?

I'd say that Satoshi specified 95% of the Bitcoin protocol in the source code that was initially published. There have been changes made since then, but the majority of Bitcoin is unchanged.

  Which person or group is in charge of defining the standard of the protocol as of now?

Essentially, you make a Bitcoin Improvement Proposal. Here's a summary of the process:

Debate the issue in the community

  The BIP champion (a.k.a. Author) should first attempt to ascertain whether the idea is BIP-able. Posting to the bitcoin-development@lists.sourceforge.net mailing list (and maybe the Development&Technical Discussion forum) is the best way to go about this.

Write a draft of the BIP

  Once the champion has asked the Bitcoin community as to whether an idea has any chance of acceptance, a draft BIP should be presented to bitcoin-development@lists.sourceforge.net. This gives the author a chance to flesh out the draft BIP to make properly formatted, of high quality, and to address initial concerns about the proposal.

The BIP editor (Currently Gregory Maxwell) reviews it

  If the BIP editor approves, he will assign the BIP a number, label it as Standards Track, Informational, or Process, give it status "Draft", and add it to the git repository. The BIP editor will not unreasonably deny a BIP. Reasons for denying BIP status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the Bitcoin philosophy.

  ...

  For a BIP to be accepted it must meet certain minimum criteria. It must be a clear and complete description of the proposed enhancement. The enhancement must represent a net improvement. The proposed implementation, if applicable, must be solid and must not complicate the protocol unduly.

Complete the reference implementation

  Once a BIP has been accepted, the reference implementation must be completed. When the reference implementation is complete and accepted by the community, the status will be changed to "Final".

We are, the Bitcoin community as a whole.


Why did the price of bitcoin increase so dramatically? I read this question on money.stackexchange, in which a user asks how to tax the speculation gain they (involuntarily) made. This guy (or girl) bought BTC for a few hundred USD a few years ago, lost the respective harddrive, and when they found it again, the BTC were (supposedly) worth a million or so USD.

So I am wondering, why did BTC appreciate so dramatically in other currencies? Is it just because of rising demand, in turn due to increasing trust in BTC?

As a corollary, could the BTC appreciation also be driven by a speculative bubble?

Sorry if this is a very noob question.

some reasons for the price-increase:

-bitcoin becomes an official currency in japan

-Australia Will Recognize Bitcoin as Money and Protect Bitcoin Businesses, No Taxes

-many people know/buy bitcon now, who did not know bitcoin some months ago (in many countries) caused by increasing media coverage

-bitcoin becomes an alternative currency in venezuela, Nigeria and some other countries caused by internal political problems

-the scaling problem seems not to be finally solved but the segwit-activation could improve the scaling-situation

-Russia’s Parliament is Discussing the Legalization of Bitcoin

-meanwhile the blockchain-technology is more established: there are no known hacks of the blockchain self

Many reasons.

The main one is the mining reward system was halved in 2016, as it also was in 2012.


6 x GPU mining rig only installs drivers for 5 I built the following rig:

5x SAPPHIRE TRI-X R9 280X 3GB GDDR5 OC (UEFI)
1x AeroCool Templarius Imperator 1150W 80 Plus Gold
1x HighPower Tech 1200w Gold Plus (HP-1200-G14C-GOLD)
1x Asrock H61 Pro BTC  Mother board
1x W.D Caviar Green 500GB SATA III HDD
1x Kingston KHX1600C9D3B1/4G
6x Powered risers 1x 16x

I Installed Windows 8.1 and plugged one GPU. It automatically installed the Radeon HD 7990 driver. Then connected the second GPU and followed the same process with the other GPUs. Everything works fine for 5 GPUs. But for the sixth one, it won't install the driver.

I try to update the driver of the sixth one but it says that the last driver is already installed.

Regards,

(since I can't comment) I had this problem too about a month ago. Try using AMD Catalyst to install the drivers.

The real answer:
Sell all of your graphics cards immediately and buy coins with the proceeds. you will never pay for the cards with all of their future mining combined at this point. If you believe in litecoin or altcoins, buy them. If your goal was to mine and exchange for bitcoins, buy bitcoins. The current estimator has 1 MH/s as being worth $127. Even if that holds for 3 months (doubtful) and you have free power (doubtful) you will have more than $380 in depreciation as people begin to sell their cards.
When asics come out, you're done. Gross revenue will go to $10/month easily.


What is the main difference between " enterprise" blockchain and regular blockchain? We have some blockchain-based cryptocurrencies such as Bitcoin or Ethereum. On the other hand,  we have some blockchain-based frameworks such as hyperledger and R3 that are designed for businesses.

Question: What is an enterprise blockchain?

Is it right those permissioned (and/or private) frameworks (e.g. hyperledger and  R3) are considered as enterprise blockchain?

The line between a blockchain and a distributed database (or ledger) is currently blurred (some would say deliberately so given the hype surrounding "blockchains" at the moment). R3 have recently concluded that it does not make sense to use a blockchain for their enterprise use case as financial institutions do not want to publish data on all their transactions to all nodes on the network. Therefore signed messages are exchanged bilaterally on R3's Corda. I am not an expert on Hyperledger but I think it is focusing predominantly on private or permissioned blockchains. These have a chain of blocks (that each contain a number of transactions) but access (ability to transact and verify transactions) is restricted to a finite number of participants. My personal opinion is that if there are transactions being batched into blocks, cryptographically attached to previous blocks and verified by all (or a subset of) nodes on a network then it should be considered a blockchain. Bitcoin and Ethereum are public blockchains. There are no restrictions in terms of those who can transact on it, view it or verify it.

As a concept, It helps to have a industry specific blockchains like a banking consortium to make sure two companies are not providing the same service to the same individual. Perhaps to weed out fraudulent transactions

Or perhaps for a services industry specific blockchain to make sure all the parties in the industry keep their promise and dont go back on the promised services. Perhaps a reputation based blockchain. It works if the major player/players adopt the block chain concept. else there wont be many players. Or a trusted 3rd party setsup the platform and the major industry players join in


I have my public key and my recovery passphrase. How do I get my private key to that address Hi I have my public address and my recovery phrase how do I create my private key for the public Bitcoin address.

As long as you have the recovery phrase, you can recover it on whichever software you generated the seeds on.

If you forgot the software or service that generated your seeds then you will have to quickly use the most trusted seed recovery service (such as blockchain.info or electrum) and after you recover the seed, immediately generate a new address or wallet and send all your coin to that address to avoid getting your coin stolen unless you planning to use that most trusted software.

Never have anyone to manually recover for you or use the untrusted source as your coin may immediately get stolen before they give you the key.

If you have a blockchain.info recovery phrase (not from an old backup), then you have enough with your recovery phrase. You can enter it here and create your new account.

In other wallets, this can also be the case. So the rule is, if your recovery phrase is some where between 12-15 English words, you actually have the Mnemonic_phrase and can recover it in a lot of wallets (Electrum, Blockchain, ...)

For other type of recovery phrase, we need to know the wallet software you are using. Because they use the name 'recovery phrase' for something non-standard.


Why to mine with a high difficult on PPLNS I'm trying poolmining ob btc-guild with the cgminer and try to calculate by testing if it is worth it or not.

One thing I wondered is: Why should I want to set a high difficult / not the lowest one, when mining?

If I am paid for the last N shared within a shift, I would want to contribute as many shares as possible. The lower the difficulty is the higher is the amount of shares, isn't it?

With about 170MH/s I have about 90 shares per hour.

The server will reject all shares that are below the difficulty it specified in your getwork request.

Reasons for the server to lower the difficulty of accepted shares:

Less variance for users

Reasons for the server to raise the difficulty of accepted shares:

Lowers bandwidth usage

Something from 4 to 10000 is about right.

170MH/s is not much, so you will not be making much more than 0.3 of a BTC every 2-3 weeks or so, if that. How much is your electricity? That will probably be your benchmark. Use this: http://tpbitcalc.appspot.com/


Is it a good idea to deposit directly into a service when withdrawing from another? I have two accounts on different Bitcoin broker services. I want to withdraw from one and deposit into the other. Is it necessary to first withdraw to my own Bitcoin wallet, or can I just withdraw from one service and deposit into the other directly, bypassing the wallet altogether? What are the advantages and disadvantages of either approach?

Many services explicitly warn users against this practice, including in their withdrawal terms clauses like "you may only withdraw to an address which is controlled by you." This is likely to be due to the details of procedures used in the case of dispute resolution, but I've never seen any explicit justification for it.
The advantages of withdrawing directly are (1) saving the network fee associated with the transaction from your intermediate wallet to the receiving service; (2) overall the transaction would be faster.
The disadvantage is potentially violating the terms of services and the associated risk.
I admit to having taken this shortcut occasionally, but I would tend to avoid it for large transactions.

If you want to deposit or withdrawal bitcoin then you will definitely need a btc wallet. Usually when you create a broker account you get a wallet and address with it.
Now if you want to transfer btc from one broker account to another then you will just need the address of the second account and you will be good to go.


Installed Bitcoind on my Ubuntu server, but where does the blockchain get downloaded? I have a fresh install of Ubuntu 12 and just installed bitcoind. How do i find out where its installed and where is it downloading the entire blockchain?

Based on the bitcoin wiki, it is shored here

Linux
By default Bitcoin will put its data here:
~/.bitcoin/

A bit more specific than a previous answer, the default path for blocks in ~/.bitcoin/blocks


How do I prevent lnd from participating in new channels? I have a lnd node that I would like to to cycle down completely. I would like to close all its channels and prevent that the node participates in any new channels while I'm waiting for the force-closed channels to mature.

What settings do I need to use in lnd to prevent my node from creating new channels, and to decline any new inbound channels?

You can set the option --maxpendingchannels=0 to disallow peers to open channels to your node.

Normally, a request to open a new channel arrives at the LND daemon via ... After doing some parsing and sanity checking of the received gRPC arguments, ... such as funding UTXOs to prevent them from being double-spent