What Is a Merkle Tree and How Does It Rely on Hash Function Security?

A Merkle Tree, or hash tree, is a data structure used to efficiently verify the integrity and content of large data sets. It works by repeatedly hashing pairs of nodes until only one root hash remains.

This root hash summarizes all the data below it. Its security entirely depends on the underlying cryptographic hash function's resistance to preimage and collision attacks, ensuring that any unauthorized data change is detectable by a change in the root hash.