So how does this ensure tamper evidence? Well, let’s go ahead and look at where hash functions are applied within Bitcoin.
The block header refers to all the metadata associated with every block.
There’s 6 fields in the implementation, but we’re going to speak to the three important ones that implement the protocol explained in module 1.
Those are the Merkle Root, Previous Block Hash, and Nonce fields.
The Merkle Root represents a summary of transactions.
The Previous Block Hash represents the chaining.
And the Nonce represents the proof-of-work.
The block header is simply the hash of all these fields concatenated.
Let’s first take a look at the Merkle Root.