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13

A 2X rate with a 50% chance of missing a winning nonce is no advantage at all. Incrementing the nonce is the easiest mechanism of choosing the next nonce to try, so you try the most nonces per second that way. That's all that matters. Perhaps you are under the mistaken impression that everyone is trying to mine the same block. That is not so. If you are a ...


11

Schnorr signatures will not replace ECDSA. Schnorr signature verification is expected to be implemented with the Taproot soft-fork using SegWit witness version 1. This means only outputs that are locked in v1 SegWit version are expected to produce a valid Schnorr signatures. ECDSA will continue to be used for spending current non-SegWit and v0 SegWit ...


8

You cannot obtain a list of transactions from the merkle tree. The merkle tree root is part of the block header, which as you said, allows quick verification of the proof-of-work. After the block header, each block contains a list of serialized transactions in the order they appear in the merkle tree. A complete block is a block header + list of ...


5

There's a reason cryptographic hash functions, like the double SHA256 used for proof-of-work in Bitcoin, are not usually described using these complexity classes that classify asymptotic behavior. In fact, there are several. A technical reason is that hash functions often do not scale. For example, it is not defined how one would extend the proof-of-work to ...


4

The system called timestamp server in the original whitepaper is currently more often referred to as a "miner". They timestamp blocks, which combine several transactions, imposing an authorative order on these transactions. This is necessary as the system cannot otherwise decide which of two conflicting but otherwise valid transactions should be accepted. ...


4

Is verification of blockchain computationally cheaper than recreating it? Yes, far easier How do you verify the blockchain integrity? Don't you also have to recalculate all the values to see whether they are valid? No. The miner has to find a value for parts of the block they can choose a value for, such that a hash of the block has a certain number of ...


3

If a miner would do so, and the transaction they include is invalid, they would produce a block with invalid transactions in them. As all full nodes on the network (not just miners) verify all transactions in blocks, they would reject this block, and the miner would lose their reward. By extension, other miners will avoid building on top of such a block, as ...


3

SHA256D, which is what Bitcoin uses, is 128 rounds, comprising 768 additions, 640 ORs 896 XORs And a bunch of bit shifts but bit shifts are free on an ASIC. (source)


3

See https://bitcoil.co.il/Doublespend.pdf. What matters is the number of blocks, not time elapsed or average time for this many blocks. Also, the idea of "wait for 6 confirmations or 1 hour" in Bitcoin is a myth. If 1 hour passes with 3 confirmations you're less secure than if 30 minutes passed with 3 confirmations, because the attacker would have had more ...


3

Not that I know of. Opencoin is still playing around with the protocol, so there probably won't be a white paper until they open source it.


3

To prove the validity of the signature, we must see that the tuple (R,s) actually came from the private key x. In particular that s was derived as s=r+cx. Obviously, we should not possess the private key x (which is the reason why we need this verification equation) so Looking at gs = RXc, we realize that we know (R,s), X and c (since c = H(X,R,m) and the ...


3

The reason that is often stated is that you would have to re-calculate all the headers with all the hash values of the whole chain which is practically un-doable. It's not the mere recalculation of new headers: miners currently create about 8×10^19 block candidates every second. However, at current difficulty levels, it takes about 4.8×10^22 block ...


2

Try looking around on http://archive.ripple-project.org/, in particular: http://archive.ripple-project.org/Main/Papers Note, that site refers to the original Ripple project and implementations of it such as RipplePay and Villages. Ripple.com is the new distributed implementation of the Ripple project and although not discussed at that site, supported by the ...


2

Each fragment starts it's own chain. Edit: I randomly selected a transaction for you to see. Try this link: http://blockchain.info/tree/7514743 and click on the yellow circles. Edit2:: Actually, this one is more interesting: http://blockchain.info/tree/50429084 In the former, the payments mostly returned in part to the original address. That's odd. The ...


2

The blockchain itself does not have any power. It is just public set of records, like a phonebook. Depending on the contract between trading parties, you arbitrage the contract disputes within the legal means you have available. However, blockchain can act as a proof of agreement and everything signed there is very hard to forge: the other party cannot ...


2

They won't be lost. But it won't be easy to get them recovered. The wiki page on Transaction Fees mentions the following: A transaction may be safely sent without fees if these conditions are met: It is smaller than 10,000 bytes. All outputs are 0.01 BTC or larger. Its priority is large enough (see the Technical Info section below) So if you have 1,000,...


2

The data that is hashed, and the hash of which must be below the current target, is the block header. The block header consists of the block version number, the hash of the previous block, the Merkle root of the transactions in the block, the time, the target, and a nonce. The generation of new bitcoins happens with a transaction, the first transaction of ...


2

Alternative algorithms used for choosing the next nonce to hash will not improve upon a simple integer increment. You will still be checking the same number of hashes per second. An increment of two instead of one will not double the hash rate. The hashing rate will be equal in both cases.


2

You need to find any nonce, so that the block becomes valid. It is of no regard, what algorithm you are using to chose a nonce, as long as the block meets or exceeds the difficulty target.


2

As you mentioned, the sum of the value of spent coins (inputs) should be superior or equal to the sum of the value of the created coins (outputs) ; the difference being the miner fee. This condition is checked by every peer of the P2P network when relaying transactions and blocks containing transactions not respecting that condition will be rejected as part ...


2

There are some excellent papers by Aviv Zohar (Red balloons, GHOST etc.) which at least touch on game theory. There's also a comprehensive list of papers at https://docs.google.com/spreadsheets/d/1VaWhbAj7hWNdiE73P-W-wrl5a0WNgzjofmZXe0Rh5sg/edit#gid=0, you can browse it to see if any could be relevant.


2

Is Bitcoin still an experiment? I don't think so. There's no control, and nobody's made one of those three panel boards. In all seriousness, though, I think Satoshi probably wrote and published Bitcoin because he found it interesting. He may also have done so because it aligned with his political views. Of course, we're speculating on the motives of a guy ...


2

Why is there more than one fast-food service? Why is there more than one internet browser? The competitive altcoin economy encourages other coins to surge with better implementations. Bitcoin has very high transaction fees as of early 2018, this is why a fork came off as Bitcoin Cash a few months ago, but Bitcoin Cash is not the only coin fighting for low ...


2

Consumers have little need for vendor-specific coins I am not an economist, but a lot of vendor-specific crypto sounds like Trading Stamps, Coupons, or maybe even Company Scrip. These might be better called "vouchers" or "tokens" than "coins". There are financial incentives for a company to issue such a token: It aids the issuer as a barrier to ...


2

1) Does hash power refers to mining nodes only? Exactly. Other nodes just make sure everything's OK, or they don't relay it. 2) We don't know how many nodes there are on the bitcoin network, correct? How do we count them? We can only count public nodes, but still, there are nonlistening nodes, nodes on the same IP, etc. So it not 100% accurate. 3) ...


2

In order to validate a block nodes must have the actual transactions themselves, even a list is insufficient. But the question "Does a block contain X" is a bit like asking "What is the sound of one hand clapping?". It would be valid to say that a "block" is nothing more than its block header or even that that hash of a block is "the block". You couldn't ...


2

But the Merkle Root is not enough to prove a transaction is in a block. All the sibling-values up the Merkle Tree are needed. Where do these values come from if they aren't already stored? Any full node that has a complete copy of the block can construct a merkle proof that proves a requested transaction identifier (txid) connects to the merkle root in a ...


2

The security of the discrete logarithm problem in a group is only as hard as that of the largest prime subgroup. Because of this, there is no security gain from working in the larger group. However; it's worse. If you're working in the larger group you must make sure to not accidentally ending up in a (much smaller) subgroup when multiplying.


2

(Disclaimer: this is not my field.) Let g be the chosen generator and n its (prime) order. In the ECDSA algorithm, these are publicly known. It is true that g generates a cyclic (abelian) group isomorphic to Z/nZ. Now a private key consists of an integer k, and the corresponding public key is the group element h = kg. (I use additive notation since we ...


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