Merkle Trees: Transaction Integrity at Scale
Construct Merkle trees and generate inclusion proofs efficiently.
Problem: Verifying Transactions Efficiently
A Bitcoin block contains ~2000 transactions. To prove transaction T is included without downloading all 2000 transactions, we need a compact proof. Merkle trees solve this: proof size = O(log n) hashes instead of O(n) transactions.
Merkle Tree Construction
Leaves: SHA256d (double-SHA256) of each transaction. Parent: SHA256d(left_child_hash || right_child_hash). Repeat until one root hash. If odd number of nodes, duplicate the last node. The root is the Merkle root stored in the block header (32 bytes).
All lessons in this course
- Hash Chains & Block Linking
- Merkle Trees: Transaction Integrity at Scale
- Proof of Work: Mining & Difficulty Adjustment
- Bitcoin Script & UTXO Signature Verification