One-way: Hash functions are one-way functions, meaning that it is possible to calculate a hash output from an input, but it is infeasible to reverse the calculation to derive an input from an output. Collision-resistant: Collision resistance means that it is difficult to find two inputs that produce the same output. This applies both to finding two matching inputs or finding an input that produces a certain output. Hash functions in blockchain
Hash functions are used in a variety of different applications. The integrity protection of a hash function is used in blockchain to create the chains that link blocks together and in the Proof of Work consensus algorithm.
The blocks’ chains
Blockchain’s name comes from the fact that it is created from blocks chained together. The chains that link the blockchain’s blocks together.
The chains in blockchain are implemented as hash functions. Each block in the blockchain contains the hash of the previous block’s header within its own header as shown above.
By incorporating a previous block hash into each block, the blockchain makes it