Merkle Hash Tree and its applications: Suppose a sender S uses a Merkle hash tree to authenticate these messages to a receiver R.

Merkle Hash Tree and its applications:   

Suppose a sender S uses a Merkle hash tree to authenticate these messages to a receiver R.

a)     What is the necessary condition for a set of data to be authenticated by Merkle-tree?

b)     After the tree is formed, what should be done before authentication can take place?

c)     Describe how Merkle-hash trees are used for memory integrity protection in computer systems and in Cryptocurrencies.