Nayuki
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How does AsicBoost work?
21 votes

Introduction AsicBoost speeds up Bitcoin mining in general (for ASICs and CPUs alike) by reducing the frequency of computing one part of the SHA-256 calculation. A Bitcoin block header is 80 bytes ...

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Javascript Bitcoin miner is it even worth it?
12 votes

It is true that mining Bitcoins like this is impossible. (I can't speak for altcoins though.) Let us run through a back-of-envelope calculation based on some facts and assumptions. Network hash rate ...

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What are version bits?
Accepted answer
9 votes

In the Bitcoin blockchain, each block has a 32-bit field called version. Right now, it takes on simple small values like 2 or 3. As an example of changes, block version 3 introduced new rules about ...

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How would you end up with more than two transaction outputs?
5 votes

When you said "as a result you have two outputs: The spent amount and the change", that is only one special case for Bitcoin transactions. In a general Bitcoin transaction, here is what actually ...

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How can importprivkey compromise wallet security when importing a publicly known private key?
Accepted answer
5 votes

The problem is rather subtle and results from a combination of behaviors. First of all, it is perfectly safe to use someone else's private key, at least in a standalone sense. Suppose the private key ...

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Get uncompressed public key from compressed form
Accepted answer
2 votes

Yes, you can convert a 33-byte compressed public key into a 65-byte uncompressed public key in Java. Here is the code to perform the operation. It is correct, robust, and only requires Java SE ...

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Bitcoins stuck - No double spend possible
Accepted answer
2 votes

Yes, waiting is the right thing to do, and pretty much the only thing you can do. Because your transaction is valid, it is likely to be incorporated into a block, even though it doesn't have a fee. ...

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Can I use Multibit private key for paper wallet?
2 votes

Yes, writing your MultiBit (non-HD) private keys on paper should work. You definitely need to write down the private keys corresponding to public addresses that have a positive balance. You also ...

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Bitcoins transactions over 1000 confirmations, but amount remains red
1 votes

In the "Amount (BTC)" column on the right side of your window, a red number means money that you are sending out, and a black number means money that you are receiving in. (The second row should have ...

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How to derive the 'addresses' field on an output from a serialized tx
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1 votes

The fields you are looking for, addresses and reqSigs, are indeed serialized in the transaction. In particular, they are implied by the scriptPubKey binary string. The scriptPubKey field is very ...

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Proving collisions on Bitcoin addresses without discovery of the private key?
Accepted answer
1 votes

To phrase the question in my own words: Can you prove that a transaction output was unlocked with a different private key than originally intended? Short answer: You can or can't, depending on the ...

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Is it possible/feasible to send out large amounts of small transactions without paying fees?
Accepted answer
1 votes

The fees charged are at the discretion of the miners, but it is possible for the network to accept free transactions under some conditions. Specifically, the main reference client will accept a free ...

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Will hashing bytes from /dev/urandom yield a secure private key?
Accepted answer
0 votes

Short answer: If you are using /dev/urandom as your source of entropy, there is no need to run sha256sum to hash the data. Instead you can use the random data directly to form your key: dd if=/dev/...

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What are the differences in these methods of creating wallets offline?
0 votes

A secure but clumsy alternative is to avoid general-purpose desktop/laptop computers and smartphones entirely. It's possible to generate keys without a real computer, which would protect you from ...

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