Homework on Consensus - Questions

  1. Consensus determines the truth because all nodes must agree on data that gets permanently recorded into the blockchain.
  2. Truth is determined in a central database only by the central authority, which can add, edit, or delete whatever it wants. The nodes do not need to agree on the edits, they simply replicate the edits made by the central authority.
  1. What does it mean when we say that in blockchain, consensus determines the truth?

In a blockchain (decentralized network or database), a consensus mechanism is used to make sure that all information that goes into the ledger is valid and that all nodes agree on that. The consensus is reached when different nodes compare their own copy of the ledger with the other nodes in order to make sure that they all match and, this way, reaching an agreement (truth) that the transaction is a valid one or not. By doing this, the network can verify all the transactions and guarantee its users the integrity of the information existing in the blockchain, removing the need for trust and replacing trust for auditing and verification.

  1. How is this different from how truth is determined in a central database?

In a central database, there is no consensus mechanism and the truth is determined by the rules established by a central authority. This central authority (single party) decides which information can go into the blockchain or not, forcing the users to trust (blindly) in this single entity for validating the transactions and maintain the integrity of the information existing on the database.

  1. All the nodes/computers are verifying the ‘transaction’ and agree with eachother that this is accurate.
    That this is the truth and consensus is achived. It is transparent

  2. The different is, that you can not verify through consensus what the truth is
    .A centeralised database is not transparent and is ‘owned’ by someone
    who can change what was/is in it.

  1. Because in Blockchain to determine if an input or action in discussion is true all the parts involved in the network need to agree with.
  2. Decentralization in Blockchain means that everyone that belongs to the network might verify and validate changes on it which is different from a regular database which in many cases are centralized and that kind of verification is made by one entity or small group.
  1. Consensus determines truth means that processes tracked by the data in a blockchain rely on the integrity of the blockchain, which itself relies on the consensus of the nodes participating in the construction of and validation of blocks in the blockchain. Therefore the validity of the states as listed in the chain are a product of consensus, and is the highest standard of truth verification possible with this type of architecture.
  2. Truth in a central database is subject to whoever has write permission to the database. Best case scenario, you are trusting whoever has write authority, and worst case, are relying on data compromised by an attacker who gained the write authorization key or password.
The different is that you can not verify through consensus the content in it.
 A centeraliced database is 'owned' by some one (authority) and they can change whats in it.
 It can also be hacked. 
 The information has to be trusted, you can not verify it as truth
  1. Everyone involved in verifying transactions on the blockchain, need to agree that the transaction is valid, therefore there needs to be consensus between all these “verifiers”. If there is consensus, that the transaction is valid, it is dertmined as the truth.
  2. A centralized authority determines if the data base is valid, or true. No verification of consensus involved - just like no milk and sugar is involved in Ivan’s coffee!

Consensus is nothing more than an general agreement of if a transaction is
correct or true by other nodes.

  1. In blockchain, when we say consensus determines the truth, we mean the truth of a valid or invalid transaction is determined by verifying the transaction by the majority of nodes in the network that must agree that it is indeed a valid transaction.

  2. Blockchains are different from how truth is determined in a central database by collectively deciding on the truth between all of the nodes/computers in the network, instead of the truth in a central database which is decided on by a central authority (in which truth cannot be verified).

What does it mean when we say that in blockchain, consensus determines the truth?

A / This is because each node of the blockchain reviews and validates the information that will be recorded in it, if one indicates that the information is not real, this information is not saved in the ledger.

How is this different from how truth is determined in a central database?

In a central database, the administrator can manipulate the information stored by deleting or modifying it. Additionally, a consensus is not required for it to be saved.

Consensus determines the truth - This means that part of the protocol is to incentivize and reward / encourage the blockchain member nodes to report the truth about the state of a transaction. This will automatically instigate trust in the users of the blockchain.

The truth in a central database can be altered, or queried to be interpreted differently.
Different queries, syntax and injections can alter the truth. I think I really understand and appreciate the differences between DB and Blockchain already.,

  1. In blockchain, consensus determines truth by the majority. Because we have the temporal blocks to fact check, it makes it extremely difficult to lie.

  2. A central database can be adjusted at any time by whoever controls it, leaving the burden of proof in the hands of anyone contesting that particular centralized database. This would seem to make it infinitely more vulnerable to dishonest manipulation.

  1. Consensus determines the truth because all members of the network have to agree whether a new transaction is legitimate and can be added to the blockchain. If a potential transaction is in some way false it will be rejected because everyone is incentivized by money to be honest.

  2. In a blockchain all members have to agree whereas in a central database it is only the central authority who makes decisions. Transparancy vs. secrecy. No changes can be made by a decentralized blockchain. A central authority has the ability to alter historical records.

Consensus is a way of verifying a transaction. When all the nodes agree that a transaction took place then we can have a high degree of certainty that it did actually happen and it was valid. This is taken to be a determination of the “truth”

In a central database, “truth” is whatever is written to it either by participants or by those controlling the database. Data can be easily controlled and manipulated by a single party so it is easy for the “truth” to be obfuscated.

  1. The mechanism used in order to select the correct state of a ledger after a transaction is made.
    (source: https://santanderglobaltech.com/en/blockchain-trust-and-uncertainty-consensus/)
  2. Truth can not be determined in a central database.
  1. all networks participants agreed that transaction happened
    2.typed in by anyone in control of database and it becomes ‘truth’ until later updated
  1. In blockchain each participant in a network checks to insure any particular transaction or action is valid. The consensus of network participants determines what is recorded to the blockchain. Because network participants are incentivised to act honestly the outcome of their consensus can be trusted.

  2. In a central database a single entity ultimately determines what is true. There are also numerous potential points of failure such as the number and quality of employees allowed access to the database and the level of security used to prevent hackers.

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  1. Blockchain is a decentralized ledger system and as such it requires a consensum mechanism that allows nodes to determine which entries and proposed new entries are legit and part of the ledger and which ones are not
  2. The aforementioned system is different from central databases truth because in blockchain the truth is determined by a consensus given by a majority of decentralized nodes part of the network, with anyone being able to be a node of the network, while a central database has no consensus mechanism, there is nothing verifying the database other than the central database itself.
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  1. Consensus = confirmed by majority , agreed by all, it is true;
  2. Central database = one decision-point, the oversight-overlord decides/confirms and we all go along with it, and no one else knows if it is true.
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  1. Consensus determine the truth because all transactions are validated by all computers on the bitcoin network before it is enter into the blockchain at all time. All nodes are financially incentivize to tell the truth.
  2. In a central database anyone who have access can enter any transaction in it at anytime.
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