Merkle Trees in Git and Bitcoin
Initial Commit blog article explaining how Git and Bitcoin both use Merkle trees and content-addressable hashing to build tamper-evident, verifiable distributed data structures.
Overview
This Initial Commit blog article by Teknikal Domain (published August 21, 2020) explains how two widely used distributed systems, Git and Bitcoin, rely on the same underlying idea: the Merkle tree combined with content-addressable storage. It defines a Merkle tree as a tree structure in which each node’s identifier is the cryptographic hash of that node’s contents, so that any change to a node changes its hash and cascades to every node above it. The piece is an accessible, non-academic introduction aimed at developers, drawing an explicit parallel between Git’s object database and Bitcoin’s block structure.
Key points
- A Merkle tree is a tree where each node is identified by the hash of its contents, so tampering with any node requires recomputing every hash above it.
- Both systems use content addressability: data is identified by the contents of that data (its hash) rather than by an arbitrary sequential ID.
- The article lists the practical properties of the cryptographic hash functions involved: the input is infeasible to derive from the output, small input changes drastically change the output, and distinct inputs should not collide.
- Git models blobs, trees, and commits as an interlinked hash structure; a commit hash is derived from its file changes, committer info, timestamp, message, and parent commit ID, which makes forging historical commits computationally impractical.
- Bitcoin groups transactions into blocks whose transactions form a Merkle tree, and each block includes a proof-of-work value that forces the block hash to meet a difficulty target (for example, leading zeros).
- In both designs, verification stays cheap for distributed participants while modification is prohibitively expensive, giving transparent, tamper-evident history.
Relevance to Truestamp
Truestamp’s proofs are built on the same primitives this article describes: a Merkle tree of hashed leaves whose data integrity rests on cryptographic hashing. Truestamp uses an RFC 6962 Merkle tree and inclusion proofs to prove an item belonged to a committed block, mirroring the Bitcoin block-and-transaction structure the source explains.
Citations
- Merkle Trees in Git and Bitcoin. Teknikal Domain, Initial Commit, August 21, 2020.