Hash

📖 Definition:

In the MPT, the Hash Node isn’t directly involved in the trie's navigational pathways or in holding the end data. Instead, it stands as a symbolic reference, encapsulating the hash of a node. This encapsulation is instrumental during the trie's persistence and retrieval stages, ensuring efficient and accurate reconstruction.

📌 Key Characteristics:

1. Storage Optimizer: When committing the trie to persistent storage, nodes such as Branch and Extension which previously pointed to other nodes, now reference a Hash Node. This facilitates a streamlined storage process and reduces overhead.

2. Reconstruction Aid: By preserving a hash reference in the Hash Node, the trie can be effectively rebuilt or a segment of it can be retrieved. Starting from the root hash and progressing through the storage, the full tree or desired parts of it can be recreated with precision.

3. Consistent Referencing: The Hash Node ensures that every node in the trie can be deterministically pointed to, based on its content, offering a consistent mechanism to access and verify data.

🛠️ Structure:

The Hash Node's Go representation is succinctly crafted as:

type HashNode struct {
	Hash []byte
}

Hash: This contains the cryptographic hash, which acts as a key when saving in storage and provides a consistent reference for node retrieval.