I am currently writing my thesis where I'm investigating the potential of blockchain technology to become the underlying technology in a system that is create and record qualifications.

I'm at the stage now where I have to put together a model but I'm struggling to understand what happens before block creation in a blockchain that uses Proof of Authority as a consensus algorithm.

Let me jump straight into where I'm struggling..Bear with me this is going to be very high-level

Just before a block is created

  1. A user node wants to store a piece of information on the blockchain so a transaction is generated.. The transaction contains the information that the user node wants to store. Upon generation of this transaction, the network already knows on which index of this blockchain the next transaction is going to go.

  2. A random validator (node with authority) on the network picks up the transaction should it be its turn to validate transactions and create blocks.

  3. Something happens here? What happens? What does the validator do to 'validate' this transaction?

  4. The validator that picked up the transaction creates the block and adds it to the blockchain.

The step that I'm finding difficult to understand despite the abundance of articles on the Internet is step #3.

Could someone please explain what exactly goes on at step? Also, please feel free to correct me if my understanding of steps #1, #2 and #4 are not correct.

1 Answer 1


Validation is same as PoW, it includes :

  1. Integrity checks (E.g.: sender has sufficient balance to cover value and transaction cost)
  2. Transaction execution check (E.g.: No exception in throws during execution of smart contract)

This is to ensure a malicious node does not broadcast invalid transactions.

  • Is it possible to have further influence on that checking process? Am I for instance able to decline transactions that have a value > 0 or = 0? How would I do that?
    – heinob
    Commented Feb 6, 2019 at 17:26
  • This will have to be part of smart contract. Smart contract can implement validations as needed for a given problem. Commented Feb 7, 2019 at 2:07
  • But how can I force users to use a smart contract instead of launching a "normal" transaction?
    – heinob
    Commented Feb 7, 2019 at 2:19

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