Homework on Blockchain and Mining Visually - Questions

Blockchain and Bitcoin 101
#1127

Wafflemaker,

That new block contains the transactions which the miner grouped together, the nonce and specific information I may enter into the block as a miner or as a smart contract which is part of my transaction. Some of the capabilities of placing information into the block have been suspended to avoid block bloat however, theoretically a great deal of information can be added in addition to these as we see with ethereum. Currently, Bitcoin prefers doing things on side chains or second layers.

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#1128

  1. When a chain of linked blocks is created, it supports security because each block must verify the previous blockā€™s data, so changing data is difficult and unprofitable to do.

  2. The hash of the current block is based upon the hash of the previous block, the transaction list of the current block, and a nonce.

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#1129

1: To guarantee the safety of the whole blockchain, so that people canā€™t change a block and say they own 1 million bitcoins, because each block is linked with the successive one and if you want to change one block you would have to change all the next ones.

2: It made of the previous hash, the nonce, the transactions that fit in the block based on the sat/byte system, and the block hash.

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#1130

  1. Why is it important that the blocks are cryptographically linked together?
    This is important because changes in any block automatically changes all proceeding blocks, and such changes would require that any blocks following any change must be re-mined in order to be accepted by the network. This of course requires significant hashing power and cost. These re-mined blocks would also have to be mined faster in order to have a longer chain than the competing original chain with unaltered blocks because new blocks mined by the entire network would be added to the longest blockchain with the most PoW.
    It hasnā€™t been discussed yet, but this is leading to the idea of a ā€œ51% attackā€ where a network of bad acting miners take over the network for their own purposes since they would have enough hashing power to mine faster than the rest of the network combined, however once again this would be phenomenally expensive and gets more costly every day, to the point at which Bitcoin is nearly entirely resistant to such attack, and miners are far more incentivized to play by the rules than not to play by them.

  2. What does the block structure look like in bitcoin?
    It looks like a block with data (ie. transactions), a hash for the previous blocks, and a nonce that is found through random guesses which lead to an acceptable new hash that is lower than the target number given by the difficulty.

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#1131

Couldnā€™t have said it better!! Great answers! :clap:

Felipe.

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#1132

1.- Because if they are cryptographically linked, you make sure that any change performed in the block will affect all the subsequent blocks. This makes everything more secure and harder to modify.

2.- Hash of the current block = hash of the previous block + hash of all the transactions in the block + the nonce. This way you are making sure that if anything gets changed in any of the previous blocks, the hash on all the subsequent blocks will change as well.

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#1133

  1. It is important that blocks are cryptographically linked together to secure the blockchain.

  2. The block structure consists of individual blocks that are linked together. The current block is hashed based on the previous has, itā€™s tx list, and nonce.

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#1134

Blockchain and Mining Visually

  1. Why is it important that the blocks are cryptographically linked together?
    The blockchain has data that is immutable. A blockchain has links connecting each block, that are based on a puzzle that miners have hashed. Having the blocks cryptographically linked together, aids in securing the data within the blocks, continuing the chain and also having each block linked together, assists the nodes and miners, who communicate with the network to receive the data, such as each transaction. In Bitcoin for example, having all the data linked, with all recorded transactions, meaning all UTXOs will be up to date, when the wallets need to query to the nodes to construct a transaction. In a supply chain, having the data in the blocks linked together will not interrupt the data from reaching each supplier on the chain, so therefore, each supplier knows where the product currently is located and where the product has been.

  2. What does the blockchain structure look like in Bitcoin?
    Bitcoins block structure at a more basic level starts with the genesis block, which is the first block that was mined. The genesis block contains the block number and a hash. The genesis block has transaction data inside it, but does not have any inputs, since it was the very first block created. In Bitcoin, the first block to have an input was block 170, but now in the present time, each block contains newly generated coins and transactions with inputs and outputs. In a more advanced explanation of the block structure, there is the header, which consists of the previous hash of the previous block, the timestamps with transactions, the merkle tree root, which is combined hashes from the merkle tree and the nonce, which is the random number to be guessed in connection with the ā€˜targetā€™. The block version is also shown as well as the block number, mining difficulty, etc.

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#1135

  1. The more solid the structure, the less likely it will break. Structural integrity of the chain will prove its authenticity. To change even one character in the blockchain destroys the integrity of the whole chain.

  2. The block contains the previous block hash, plus the data of the current block, and then adding in a random nounce to calculate a hash to determine if it equals the target hash.

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#1136

  1. Why is it important that the blocks are cryptographically linked together?
    -`because it secures the network and by linking them you ensure that if someone changes any history that the change gets rejected.

  2. What does the block structure look like in bitcoin?
    It has the previous hash, transaction list and the nonce

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#1137

I agree with this answer and i can complete the answer saying that the cryptographic link make the remine exponentially difficult

  1. It is a set of input (UTXOs) output and btc values
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#1138

  1. To ensure the immutability of the ledger. Changing the data in a block breaks its own hash and the hash of the blocks onwards and consequently they need to be mined again (new PoW). This is perceived as impossible to pull off, due to the massive computing power and energy that it would take.

  2. Block: # (the blockā€™s sequential number/position in the chain)
    Nonce: (the random number guessed that gave the block a hash below the target)
    Data: (the TXsā€™ list)
    Prev: (the hash of the previous block, a number in the hexadecimal notation)
    Hash: (the hash of the present block, a number in the hexadecimal notation)

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#1139

Exactly. And older block has more proof of work. :smiley:

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#1140

There is a lot more than that. If we take a look at your first answer, you said that the blocks are cryptographically linked. How can that be achieved? There is an important part of a block structure that enables us to do such a thing. Do you think you could figure out what it is? Also feel free to mention the other part of the block structure as well. :smiley:

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#1141

  1. If a previous block is changed, the hash is changed. This breaks the link to the next block.

  2. The block is made up of the transactions, the previous hash and a nonce.

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#1142

  1. It is important for blocks to be cryptographic be linked for security. This way if changes were to be made it will break the block and all the blocks to follow thereafter.

  2. The block structure is set up by the previous hash rate, the current block transactions and a algorithmic none that has to be guessed based off of the mining difficulty.

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#1143
  1. Cryptographically linking blocks together ensures security of the blockchain. No transactions can be changed in previous blocks because it would break the link to the previous block and invalidate the transaction.

2.The hash rate is based on the transactions in the block + the previous hashes.

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#1144

  1. It is important to link the blocks together cryptographically because making any changes in one block alters its hash which is part of the hash value of the following block. Changing one block creates a mismatch in all blocks and breaks the chain apart. The entire blockchain would have to be ā€œminedā€ all over beginning at the block where the change was made, and the miner would also have to keep up with the hash rate of the rest of the network, because ā€œtruthā€ is determined by the longest chain.

  2. The bitcoin block structure contains a record of the block reward (created coins), each transaction, the hash value of the previous block, and the hash value of the block itself created from the mining process (combining these values together with a nonce that results in a value lower than the target number after being run through the hashing algorithm).

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#1145

Homework on blockchain and mining:
1.The block are crytographically linked for security and to maintain immutability.
2.A block structure includes the block number, previous block hash, transaction data, nounce and the current block hash.

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#1146

  1. Why is it important that the blocks are cryptographically linked together?
    A. It is important that the blocks are cryptographically linked together because this adds security to the block chain. If a block is changed it will effect the cryptography of the other blocks and disrupt the block chain. You would then have to re-mine all subsequent blocks before the next block at the end of the block chain is mined to make it work, which is virtually impossible at the moment.

  2. What does the block structure look like in bitcoin?
    A. The Block has the block number, nonce, Transactions, Previous hash, and the hash of the current block.

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