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There are a number of research papers that cover the question "Do you need a blockchain?", e.g. the eponymous paper by Wüst & Gervais (2017) and the extensive Blockchain Technology Overview by NIST (2018). At a quick glance, the article When do you need blockchain? Decision models. by Meunier appears to provide a survey collecting a broad range ...


6

You don't necessarily need to "buy" external participants You can have a not-a-cryptocurrency blockchain that's maintained and controlled by a single mostly-trusted entity without any proof of work requirement. This makes the maintenance of the blockchain cheap and efficient, while still enforcing some technical constraints on what that entity can ...


5

I thought 3 random "validators" could be picked to do the hash-math. Only if all 3 get the same result, it is stored to a "temporary" blockchain. And only if say the next 3 blocks worked with that result, it will be placed in the actual Blockchain. If 1 of 3 gets a different hash, 3 other random people are selected to validate. The devil ...


4

This answer kind of jumps around a bit, but I think it's all relevant info. There is a TL;DR at the bottom that more directly answers the question. Distributed Ledger Technology is totally reliant on participation to establish the principle of Distributed Trust. If there are not enough independent actors in the network, you cannot rely on the immutability ...


3

My question is, if that is the case, why can’t the verification only check against transactions signed by Alice, why does it have to check against the entire blockchain? A node has no concept of who controls certain outputs. So there is no way to 'check all of Alice's outputs', how would the node be able to ascertain which outputs belong to her? Rather, the ...


2

Distributed Ledger Technology is totally reliant on participation to establish the principle of Distributed Trust. If there are not enough independent actors in the network, you cannot rely on the immutability of the ledger. This is always an advantage of blockchain over every other technology and never a disadvantage. Think about this for just a second. ...


2

You cannot say for sure. The three options are potentially true. However, many clients build transactions with the change output as the last output. So, following this convention, I would say option 2 is the most likely.


2

I was wondering, how is this attribute populated? The site uses an index that simply remembers this information. If a block B is seen that contains a transaction T, an entry is stored in the database that signifies "transaction T is in block B". by looking at transaction inside of your UTXO, check in which block transaction was included (and then ...


1

As a third party to the transaction, its hard to say what the most likely case is. You can guess, but there are a number of possibilities, and some wallet software will deliberately create transactions which confuse this sort of analysis. To add to your list of possibilities: Someone sent 25.99 bitcoin to another person/organization Someone sent 1 bitcoin ...


1

2 confirmations means the transaction was included in a valid block and that block was continued by another valid block. Option 3, although it should be next block (older than the one that contains the transaction) instead of previous block.


1

To be short: Without a ledger recording everything, it won't be possible to know whether Alice had ever signed another double-spending transaction. Even if we have a ledger, or even better, a tamper-evident, append-only ledger (which is the inherent nature of blockchain), it's still enough, because the ledger itself could still be maliciously truncated & ...


1

Simply, the block chain is to prevent double spending. Otherwise Alice could present different transactions to different people, all with valid signatures, that spend the same money in alternate ways. With a ledger containing every transaction that has been executed, we know that the money can be spent exactly once.


1

First, the common lingo for these "cashback transactions" is "change outputs", and "chain analysis" is a thing whole businesses have sprung up around. There are a few indicators that allow making educated guesses on which outputs may be change, e.g. round numbers (e.g. three outputs with round amounts and one not) wallet fingerprinting (e.g. all inputs are ...


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