node – Private Blockchains: validation of the blocks

I'm a software developer trying to understand blockchain at the code level

I have the following problem:

There is a private blockchain. This private blockchain has no relation to mining. It only contains a number of nodes that create and validate blocks and the chain.

Let's say Node ON modified a block (x) and node B requested the block x to node A

How does node B actually know that node A is invalid since block? X is valid for node A, so it can apply to node B because node B asks for it for the first time.

  • This block chain uses the credential

Ask:

  1. How can we make sure that the chain is actually valid when no mining is involved and only the nodes are building blocks and sending them through the network (I've been thinking about putting digital signatures and their public keys in each block for the nodes to do However, the signature that would be created from the contents of the block does not work because a malicious node can create a new public key and thus a new signature for its modification.
    1. Do we need a kind of voting process in which node B requests many examples of the block X Node B can thus decide which block is valid by knowing the most commonly used hash of the answers / blocks it has received.
    2. How would you do it? How would you solve this problem?

Remember, this is not cryptos, not bitcoin, not mining, just blockchain technology.

For more information on why I ask this, you may want to see my previous question:

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