## Keyboard shortcuts

Press `←` or `→` to navigate between chapters

Press `S` or `/` to search in the book

Press `?` to show this help

Press `Esc` to hide this help

- Auto
- Light
- Dark

# Algorand Specifications

A light block header is a structure containing a subset of fields from Algorand’s _block header_ and the commitment of said block header.

Light block header contains the following components:

- The block’s _seed_, under msgpack key `0`.
- The block’s _hash_, under msgpack key `1`.
- The block’s _genesis hash_, under msgpack key `gh`.
- The block’s _round_, under msgpack key `r`.
- The block’s [SHA-256](https://specs.algorand.co/crypto/crypto-sha256) transaction commitment, under msgpack key `tc`.

The light block header _commitment_ for rounds (X⋅δSP,…,(X+1)⋅δSP] for some number XX, defined as the root of a [vector commitment](https://specs.algorand.co/crypto/crypto-vector-commitment) whose leaves are light block headers for rounds X⋅δSP,…,(X+1)⋅δSP respectively.

The hash function [SHA-256](https://specs.algorand.co/crypto/crypto-sha256) is used to create this vector commitment.