David Schwartz
  • Member for 10 years, 5 months
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How do Bitcoin clients find each other?
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131 votes

Bitcoin clients use several methods to locate other clients. The primary method is a list of nodes from a previous connection to the network. The works very well for everything but your first ...

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How does merged mining work?
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100 votes

Merged mining allows a miner to mine for more than one block chain at the same time. The benefit is that every hash the miner does contributes to the total hash rate of both (all) currencies, and as a ...

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Does hoarding really hurt Bitcoin?
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96 votes

TL;DR: No. The argument is basically that hoarding will make Bitcoins so valuable that nobody will be willing to offer people enough to part with them. Does that pass the giggle test? Another way of ...

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What is a compressed Bitcoin key?
66 votes

A compressed key is just a way of storing a public key in fewer bytes (33 instead of 65). There are no compatibility or security issues because they are precisely the same keys, just stored in a ...

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What exactly is Mining?
57 votes

Mining is the process of securing transactions and committing them into the bitcoin public chain. It requires winning a kind of computational lottery where each hash you perform is like buying one ...

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What methods could a government use to shutdown Bitcoin?
47 votes

Honestly, I think the best way for the government to shut down Bitcoin would be as a secret project. Simply construct a VLSI ASIC miner built using 40nm/1Gtransistor technology and build 100,000 of ...

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Should I leave the Bitcoin client open?
46 votes

I would add two points to those already mentioned: First, if you cannot accept inbound connections (because you are behind NAT or have specifically disabled them) you won't really be helping the ...

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Is there a way to set up proof-of-work systems so they would be even more useful?
42 votes

I think the premise of the question is not correct. The work is not useless, it secures the transactions. The public hash chain ensures that Bitcoins can only be spent once. The mechanism piles ...

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Have any cryptography experts vetted the bitcoin source code?
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40 votes

"It looks good to me" tends to make for a pretty boring paper. Security expert Dan Kaminsky has given talks and written articles about the Bitcoin system. His two main points are that it cannot scale ...

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How does change work in a bitcoin transaction?
39 votes

First, let's clarify the difference between accounts and addresses. "Accounts" are used for the convenience of people to track their funds. This is primarily used to track the source of funds. Since ...

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How does the bitcoin client make the initial connection to the bitcoin network?
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36 votes

The Bitcoin client has a number of sources that it uses to locate the network on initial startup. In order of importance: 1) The primary mechanism, if the client has ever run on this machine before ...

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Nonce size - Will it always be big enough?
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36 votes

The difficulty is already to the point where it requires over a quadrillion hashes to solve a block. 2^32 is only 4 billion. Fewer than one in a billion times will there be any nonce that makes the ...

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Can I use my wallet on different computers?
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36 votes

It is, with three provisos. Never run the same wallet on more than one computer at a time. Never run an older copy of a wallet when a newer version exists. If you send any funds, make sure to keep ...

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How do Scripts work?
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35 votes

Scripts are one of Bitcoin's more clever features. The most obvious way to implement a crypto-currency is to make a transfer be to a public key. To claim the transfer, you sign with the corresponding ...

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What are the bandwidth requirements of a mining rig?
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34 votes

With pooled mining, at 900Mhash/s, you'll need a new work unit every 3 seconds or so. Each work unit requires about 256 bytes out and about 768 bytes back. So that's 700 bits per second out and about ...

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How is block-solution-withholding a threat to mining pools?
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33 votes

Every pool is vulnerable to the threat. And there's pretty much nothing they can do about it other than perhaps to try to force their miners to use a closed source mining program that they try to make ...

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How does Ripple solve the double-spend problem?
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33 votes

The details are very complex, but the core concept is fairly simple. Ripple solves the double-spend problem by consensus. The analogy I use is an "agreement room". To walk into the room, you have to ...

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Who gets Bitcoin transaction fees?
Accepted answer
32 votes

The fee goes to the miner who mines the block that includes your transaction. The fee is based on the size (in bytes) of the transaction and the age of its inputs (how long ago the coins spent were ...

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What is the coinbase?
31 votes

The term "coinbase" is used to mean many different things. But the two you're probably asking about are: The "coinbase transaction" is the transaction inside a block that pays the miner his block ...

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

RIPEMD was used because it produces the shortest hashes whose uniqueness is still sufficiently assured. This allows Bitcoin addresses to be shorter. SHA256 is used as well because Bitcoin's use of a ...

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Why is bitcoin written in C++?
28 votes

I gave a keynote address at cppcon 2016 about almost this exact issue. There are a variety of reasons why C++ is an excellent language choice for blockchain applications like Bitcoin. Blockchain ...

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What are bitcoin "confirmations"?
28 votes

If you don't grasp the basic concept, imagine for a second that a network outage split the bitcoin network in half. I could send one transaction giving 30 bitcoins to Abel to one half and one ...

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Is it worthy to use "bitcoin usb block erupter"
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26 votes

A typical USB block erupter will get 333MH/s under realistic conditions. Today, a share is worth about 1/156 of a penny and 333MH/s will get you a share every 13 seconds. That comes out to 43 cents ...

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How is it possible to launder bitcoins?
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25 votes

Say I received 10 bitcoins on a Bitcoin address I publicly advertise for donations. Anyone looking at the blockchain can put that address in a search engine and find me. Now say I want to use those 10 ...

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How is Bitcoin supposed to serve as currency when it is all but impossible to spend at the moment (12/2017)?
24 votes

You were probably trying to pay on the blockchain itself. That's like trying to pay for lunch by moving dollars through the Federal Reserve. You should use some system designed to move small ...

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How Ripple is different from Bitcoin and other crypto-currencies?
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23 votes

There are several major differences. Bitcoin is a currency with a built in payment system for its currency. The XRP Ledger is a payment system for arbitrary currencies with support for cross-currency ...

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What are stale shares and what can I do to avoid them?
23 votes

A stale share occurs when you find a share and submit it to the mining pool after the pool has already moved on to the next block. The percentage of stale shares should be very low if everything's ...

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What is the coin selection algorithm?
23 votes

Yes, that is exactly what the client does. It uses heuristics to do this, solving a subset/sum or knapsack problem. It uses a multi-pass approach, first trying to use only coins with at least six ...

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Byzantine fault-tolerant consensus - Why 33% threshold
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22 votes

We have a mathematical proof that to tolerate n malicious nodes, you need 2n + 1 good nodes. The full proof is found in G. Bracha and T. Rabin, Optimal Asynchronous Byzantine Agreement, TR#92-15, ...

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Is it possible to send bitcoins without paying a fee?
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22 votes

It is possible to send Bitcoins without paying any fee. The easiest way is if your transaction meets the following requirements: The transaction only sends coins to one address, plus the return of ...

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