Merkle Trees

Synonyms

Authentication trees; Hash trees; Merkle hash trees

Definition

Merkle trees are data structures devised to authenticate, with a unique signature, a set of messages, by at the same time making an intended verifier able to verify authenticity of a single message without the disclosure of the other messages. In particular, given a set of messages M = {m₁,…, m_n}, the Merkle tree build on them is a binary tree whose leaves contain the hash value of each message m in M, whereas internal nodes contain the concatenation of the hash values corresponding to its children.

Key Point

A Merkle tree is a data structure introduced by Merkle in 1979 [1] to improve the Lamport-Diffie one-time signature scheme [2]. In this digital signature scheme, keys can be used to sign, at most, one message. This implies that for each signed message a new public key has to be generated and published. As consequence, Lamport-Diffie one-time digital signature scheme requires publishing a large amount of...